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We theoretically study the nature of parametrically driven dissipative Kerr soliton (PD-DKS) in a doubly resonant degenerate micro-optical parametric oscillator (DR-DμOPO) with the cooperation of χ (2) and χ (3) nonlinearities. Lifting the assumption of close-to-zero group velocity mismatch (GVM) that requires extensive dispersion engineering, we show that there is a threshold GVM above which single PD-DKS in DR-DμOPO can be generated deterministically. We find that the exact PD-DKS generation dynamics can be divided into two distinctive regimes depending on the phase matching condition. In both regimes, the perturbative effective third-order nonlinearity resulting from the cascaded quadratic process is responsible for the soliton annihilation and the deterministic single PD-DKS generation. We also develop the experimental design guidelines for accessing such deterministic single PD-DKS state. The working principle can be applied to different material platforms as a competitive ultrashort pulse and broadband frequency comb source architecture at the mid-infrared spectral range.

We present temporal quadratic solitons in doubly resonant temporal dispersive optical parametric oscillators without a walk-off in numerical simulations. In frequency domain, these cavity solitons correspond to coherent dual-combs with smooth envelopes in half-harmonic and pump fields. We also investigate the soliton existence region, and the soliton behavior with parameters in this cavity system. We believe our work offers valuable insights into the practical generation of quadratic soliton combs in optical parametric oscillators.

We present a gigahertz (GHz)-repetition-rate optical parametric oscillator (OPO) pumped by an electro-optic comb at 1.03 µm, delivering sub-picosecond signal pulses across 1.5–1.7 µm from a MgO-doped periodically poled L i N b O 3 crystal. Using a pump power of 5 W at 14.2 GHz repetition rate, 378 mW of signal power is obtained at 1.52 µm from a subharmonic cavity, corresponding to a signal extraction efficiency of 7.6%. By cascading a Mach–Zehnder modulator, the pump pulse repetition rate can be divided by any integer number from one to 14, allowing the OPO to operate with a flexible repetition rate from 1 to 14.2 GHz. A strategy leading to quasi-continuous repetition rate tunability of the OPO is also discussed.

Networks of optical oscillators simulating coupled Ising spins have been recently proposed as a heuristic platform to solve hard optimization problems. These networks, called coherent Ising machines (CIMs), exploit the fact that the collective nonlinear dynamics of coupled oscillators can drive the system close to the global minimum of the classical Ising Hamiltonian, encoded in the coupling matrix of the network. To date, realizations of large-scale CIMs have been demonstrated using hybrid optical-electronic setups, where optical oscillators simulating different spins are subject to electronic feedback mechanisms emulating their mutual interaction. While the optical evolution ensures an ultrafast computation, the electronic coupling represents a bottleneck that causes the computational time to severely depend on the system size. Here, we propose an all-optical scalable CIM with fully-programmable coupling. Our setup consists of an optical parametric amplifier with a spatial light modulator (SLM) within the parametric cavity. The spin variables are encoded in the binary phases of the optical wavefront of the signal beam at different spatial points, defined by the pixels of the SLM. We first discuss how different coupling topologies can be achieved by different configurations of the SLM, and then benchmark our setup with a numerical simulation that mimics the dynamics of the proposed machine. In our proposal, both the spin dynamics and the coupling are fully performed in parallel, paving the way towards the realization of size-independent ultrafast optical hardware for large-scale computation purposes., Comment: 7 pages, 3 figures

Agradecimentos: The authors acknowledge support from the National Institute of Standards and Technology, the DARPA SCOUT Program, the National Science Foundation (Grand No. 1708743), and the Air Force Office of Scientific Research (Grants No. FA9550-16-1-0016 and No. FA9550-16-1-0164). F. C. C. acknowledges support from Fapesp (Grant No. 2018/26673-5). We thank E. Baumann, B. Changala, and D. Lesko for valuable comments Abstract: The mid-infrared atmospheric window of 3-5.5 mu m holds valuable information regarding molecular composition and function for fundamental and applied spectroscopy. Using a robust, mode-locked fiberlaser source of < U fs pulses in the near infrared, we explore quadratic (chi((2))) nonlinear optical processes leading to frequency comb generation across this entire mid-infrared atmospheric window. With experiments and modeling, we demonstrate intrapulse difference frequency generation that yields few-cycle mid-infrared pulses in a single pass through periodically poled lithium niobate. Harmonic and cascaded chi((2)) nonlinearities further provide direct access to the carrier-envelope offset frequency of the near infrared driving pulse train. The high frequency stability of the mid-infrared frequency comb is exploited for spectroscopy of acetone and carbonyl sulfide with simultaneous bandwidths exceeding 11 THz and with spectral resolution as high as 0.003 cm(-1). The combination of low noise and broad spectral coverage enables detection of trace gases with concentrations in the part-per-billion range FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Fechado

A method to fabricate GaAs microcavities using only a soft mask with an electrolithographic pattern in an inductively coupled plasma etching is presented. A careful characterization of the fabrication process pinpointing the main routes for a smooth device sidewall is discussed. Using the final recipe, optomechanical microdisk resonators are fabricated. The results show very high optical quality factors of Q(opt) > 2 x 10(5), among the largest already reported for dry-etching devices. The final devices are also shown to present high mechanical quality factors and an optomechanical vacuum coupling constant of g(0) = 2 pi x 13.6 kHz enabling self-sustainable mechanical oscillations for an optical input power above 1 mW FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Aberto

Orbital angular momentum is a discrete degree of freedom that can access an infinite dimensional Hilbert space, thus enhancing the information capacity of a single optical beam. Continuous variables field quadratures allow achieving some quantum tasks in a more advantageous way with respect to the use of photon-number states. Here, we use a hybrid approach realizing bipartite continuous-variable Gaussian entangled state made up of two electromagnetic modes carrying orbital angular momentum. A q-plate is used for endowing a pair of entangled beams with such a degree of freedom. This quantum state is then completely characterized thanks to a novel design of a homodyne detector in which also the local oscillator is an orbital angular momentum-carrying beams so allowing the direct detection of vortex modes quadratures.

International audience; Chirp of the pulses generated in the 1.4 µm-1.8 µm spectral ranges and in a singly resonant OPO build around a 3 mm long PPLN crystal pumped at 108 MHz by 40 nJ, 1 ps chirped or 350 fs weakly chirped pump pulses centered at 1035 nm is analyzed. Whatever the chirp of the pump pulses, we achieved a pump to signal conversion efficiency > 30%. We demonstrate that by adjusting the cavity length around synchronism condition, chirped or almost chirped free (down to 80 fs) signal pulses are generated. A simple mechanism accounts for this phenomenon.

A robust approach to excitation and control of large amplitude standing magnetization waves in an easy axis ferromagnetic by starting from a ground state and passage through resonances with chirped frequency microwave or similar alternative drives (spin torque, additional periodic anisotropy) is proposed. The formation of these waves involves two stages, where in the first stage, a spatially uniform, precessing magnetization is created via passage through a resonance followed by a self-phase-locking (autoresonance) with a constant amplitude drive. In the second stage, the passage through an additional resonance with a spatial modulation of the driving amplitude yields transformation of the uniform solution into a doubly phase-locked standing wave, whose amplitude is controlled by the variation of the driving frequency. The stability of this excitation process is analyzed both numerically and via Whitham's averaged variational principle. © 2019 American Physical Society.

Agradecimentos: We thank J. E. Schiel and T. Mouchahoir for providing the NISTmAb samples and D. Lesko for providing the NH3 lecture bottle sample. We thank N. Newbury, D. Carlson, K. Cossel, M. Weichman, and C. Meuse for providing comments on the manuscript. We thank A. Bartels for advice on the experimental setup. Funding: This work was supported by the Defense Advanced Research Projects Agency (DARPA), National Institute of Standards and Technology (NIST), National Research Council (NRC/National Academies of Sciences, Engineering, and Medicine), and Air Force Office of Scientific Research (AFOSR) (FA9550-16-1- 0016). F.C.C. acknowledges funding from Fapesp (grant # 2018/26673-5). U.E. and J.B. acknowledge funding from "Severo Ochoa" Programme for Centres of Excellence in R&D (SEV-2015-0522), MINECO "FIS2017-89536-P", AGAUR "2017 SGR 1639", EU FET "PETACom" (829153), ERC Advanced Grant "TRANSFORMER" (788218) and PoC miniX (840010) Abstract: Probing matter with light in the mid-infrared provides unique insight into molecular composition, structure, and function with high sensitivity. However, laser spectroscopy in this spectral region lacks the broadband or tunable light sources and efficient detectors available in the visible or near-infrared. We overcome these challenges with an approach that unites a compact source of phase-stable, single-cycle, mid-infrared pulses with room temperature electric field-resolved detection at video rates. The ultrashort pulses correspond to laser frequency combs that span 3 to 27 mm (370 to 3333 cm(-1)), and are measured with dynamic range of gt;10(6) and spectral resolution as high as 0.003 cm(-1). We highlight the brightness and coherence of our apparatus with gas-, liquid-, and solid-phase spectroscopy that extends over spectral bandwidths comparable to thermal or infrared synchrotron sources. This unique combination enables powerful avenues for rapid detection of biological, chemical, and physical properties of matter with molecular specificity FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Fechado

Agradecimentos: Defense Advanced Research Projects Agency (DARPA); Defense Sciences Office (DSO) under the SCOUT program; Fundação de Pesquisa de São Paulo (Fapesp) (2018/26673-5). We thank Travis Autry, Fabrizio R. Giorgetta, Esther Baumann, Jeffrey Shainline, and David Carlson for useful discussions and inputs on the manuscript. F.C.C. acknowledges funding from FAPESP. This is a contribution of NIST, an agency of the U.S. government, not subject to copyright. Product disclaimer: Any mention of commercial products is for information only; it does not imply recommendation or endorsement by NIST Abstract: Nanophotonic waveguides with sub-wavelength mode confinement and engineered dispersion are an excellent platform for application-tailored nonlinear optical interactions at low pulse energies. We present fully air-clad suspended silicon waveguides for infrared frequency comb generation with optical bandwidth limited only by the silicon transparency. Precise lithographic control over the waveguide dispersion enables tailored infrared frequency comb generation across a bandwidth of 2.0-8.8 mu m (1130-5000 cm(-1)), with the broadest simultaneous bandwidth covering 2.0-7.7 mu m. Novel fork-shaped couplers provide efficient input coupling with only 1.5 dB loss. The coherence, brightness, and stability of the generated light are highlighted in a dual-frequency comb setup in which individual comb lines are resolved with 30 dB extinction ratio and 100 MHz spacing in the wavelength range of 4.9-8.8 mu m (1130-2050 cm(-1)) using three different waveguide widths. These sources are used for broadband gas- and liquid-phase dual-comb spectroscopy with 100 MHz comb line resolution. We achieve a peak spectral signal-to-noise ratio of 10 root Hz across a simultaneous bandwidth of 6.3-8.2 mu m (1220-1590 cm(-1)) containing 112,200 comb lines. These results provide a pathway to further integration with the developing high-repetition-rate frequency comb lasers for compact sensors with applications in chip-based chemical analysis and spectroscopy FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto

Agradecimentos: The authors acknowledge support from Grant No. 2010/08448-2, Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Project No. 473847/2012-4 by the Conselho Nacional de Desenvolvimento Científico e Tecnológico, by the Instituto Nacional de Ciência e Tecnologia de Informação Quântica (INCT-IQ), and by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. M. Martinelli would like to thank Stephen P. Walborn for the discussions about the paper. The authors would like to thank the anonymous referees for fruitful suggestions that greatly contributed to a better presentation of the results Abstract: We demonstrate, theoretically and experimentally, the generation of hexapartite modal entanglement by the optical parametric oscillator (OPO) operating above the oscillation threshold. We show that the OPO generates a rich structure of entanglement among sets of six optical sideband modes interacting through the nonlinear crystal. The class of quantum states thus produced can be controlled by a single parameter, the power of the external laser that pumps the system. Our platform allows for the generation of massive entanglement among many optical modes with well defined hut vastly different frequencies, potentially bridging nodes of a multicolor quantum network FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Aberto

Agradecimentos: This work was supported by NIST and the Defense Advanced Research Projects Agency (DARPA), Defense Sciences Office (DSO) under the SCOUT program. The authors would like to thank Nathan Newbury, Ian Coddington, Scott Papp, and Franklyn Quinlan for useful discussions and inputs on the manuscript. We also acknowledge the support of the NIST Boulder microfabrication facility in fabrication of the Si waveguides. This is a contribution of NIST, an agency of the US government, not subject to copyright. Product disclaimer: Any mention of commercial products is for information only; it does not imply recommendation or endorsement by NIST Abstract: Laser frequency combs, with their unique combination of precisely defined spectral lines and broad bandwidth, are a powerful tool for basic and applied spectroscopy. Here, we report offset-free, mid-infrared frequency combs and dual-comb spectroscopy through supercontinuum generation in silicon-on-sapphire waveguides. We leverage robust fabrication and geometrical dispersion engineering of nanophotonic waveguides for multi-band, coherent frequency combs spanning 70 THz in the mid-infrared (2.5 mu m-6.2 mu m). Precise waveguide fabrication provides significant spectral broadening with engineered spectra targeted at specific mid-infrared bands. We characterize the relative-intensity-noise of different bands and show that the measured levels do not pose any limitation for spectroscopy applications. Additionally, we use the fabricated photonic devices to demonstrate dual-comb spectroscopy of a carbonyl sulfide gas sample at 5 mu m. Thiswork forms the technological basis for applications such as point sensors for fundamental spectroscopy, atmospheric chemistry, trace and hazardous gas detection, and biological microscopy Aberto

Orientadores: Gustavo Silva Wiederhecker, Thiago Pedro Mayer Alegre Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin Resumo: A geração de pentes de frequência tem sido um campo ativo de pesquisa, com aplicações indo de metrologia a astronomia, passando por espectroscopia e medidas de distância mais precisas. Um dos principais métodos de geração de pentes é por meio de mistura de quatro ondas, um processo não-linear de terceira ordem no qual um par de fótons é substituído por outro par com novas frequências (conservando energia e momento). A alta intensidade óptica necessária para o desencadeamento deste processo é obtida através da intensificação ressonante do campo eletromagnético no interior de uma microcavidade, que confina a luz em pequenos volumes e reduz a potência de entrada. Além da vantagem energética e do potencial para miniaturização e produção em larga escala, essa plataforma possibilita a customização de parâmetros do pente de frequência: a taxa de repetição do pente escala com o inverso do raio da cavidade, pois as bandas laterais criadas devem coincidir com as frequências harmônicas do dispositivo. A largura de banda do pente também pode ser controlada com um planejamento cuidadoso da geometria do dispositivo, pois é limitada em grande parte pela variação do intervalo espectral livre com a frequência. Nesta dissertação, estudamos como a dispersão modal de um microdisco de óxido de silício em forma de cunha é modificada por mudanças em suas características geométricas. Para tanto, desenvolvemos a habilidade de controlar o ângulo dos dispositivos fabricados e de medir a dispersão do modo fundamental a partir de seus espectros de transmissão. Os resultados (corroborados por simulações numéricas) mostram que a dispersão (em 1550 nm) vai de normal a anômala com o aumento do ângulo. Ainda, utilizamos os dispositivos fabricados para gerar pentes de frequência no regime de dispersão anômala e concluimos que a dinâmica de formação é bem descrita pelo formalismo de expansão modal Abstract: Frequency comb generation has been a very active research field, with applications ranging from frequency metrology to astronomy and precise distance measurement. One of the main methods of comb generation is through cascaded four wave mixing, a third order nonlinear process in which a pair of photons is replaced by another pair with shifted frequencies while conserving energy and momentum. The high optical intensity needed to trigger the process is achieved by confining the light to a microcavity, thus reducing the power consumption by the resonant enhancement of the internal electromagnetic field. Besides the scalability potential and the energetic advantages, this microcavity-based platform enables the customization of comb parameters: the repetition rate scales with the inverse of the cavity radius as the generated sidebands should match the harmonic frequencies of the device. Also, the bandwidth is limited by the change in the free spectral range with frequency, which could be set to near zero values by carefully designing the geometry of the optical device. In the present dissertation, we study how the modal dispersion is affected by a change in the geometrical features of a silicon oxide wedge microdisk. To that end, we developed the expertise to control the wedge angle of the fabricated devices and to measure the dispersion of the fundamental mode from their transmission spectra. The results (corroborated by numerical simulations) show that the dispersion (at 1550 nm) goes from normal to anomalous as the wedge angle is increased. Furthermore, we used the fabricated devices to generate frequency combs in the anomalous dispersion regime, and concluded that the formation dynamics is well described by the modal expansion formalism Mestrado Física Mestra em Física CAPES 1583077/2016 FAPESP 2016/05038-4

We report a pulsed singly-resonant optical parametric oscillator based on orientation-patterned gallium phosphide pumped by a Q-switched Nd:YAG laser. The mid-IR idler can be tuned across 2.8-3.1 μm with an average power of 20 mW.

Agradecimentos: Defense Advanced Research Projects Agency (DARPA); National Institute of Standards and Technology (NIST); National Science Foundation (NSF) (1708743); Air Force Office of Scientific Research (AFOSR) (FA9550-16-1-0016) Abstract: Spectroscopy in the molecular fingerprint spectral region (6.7-20 mu m) yields critical information on material structure for physical, chemical, and biological sciences. Despite decades of interest and effort, this portion of the electromagnetic spectrum remains challenging to cover with conventional laser technologies. In this paper, we present a simple and robust method for generating super-octave, optical frequency combs in the fingerprint region through intra-pulse difference frequency generation in an orientation-patterned gallium phosphide crystal. The attainable brightness from this tabletop source reaches the same level achievable by infrared synchrotron radiation with a bandwidth spanning from 4 to 12 mu m. We demonstrate the utility of this unique coherent light source for high-precision, dual-frequencycomb spectroscopy of methanol and ethanol vapor. These results highlight the potential of laser frequency combs for a wide range of infrared molecular sensing applications from basic molecular spectroscopy to nanoscopic imaging fechado

Agradecimentos: Sao Paulo Research Foundation (FAPESP) (2008/57857-2, 2012/50259-8, 2013/20180-3, 2015/11779-4); National Council for Scientific and Technological Development (CNPq) (574017/2008-9); Coordination for the Improvement of Higher Education Personal (CAPES); Administrative Department of Science, Technology and Innovation (Colciencias) Abstract: The understanding of how bending modifies the dispersion of optical fibers, in particular, the zero-dispersion wavelength (lambda(0)), is essential in the development of compact nonlinear optical devices such as parametric amplifiers, wavelength converters, soliton lasers and frequency comb generators. Typically, substantial variations in the parametric gain and/or conversion efficiency are significant for changes in lambda(0) of similar to 0.1 nm, which occur for variations on the bending radius (R-b) of 1 cm or less. Measuring lambda(0) as a function of bending radius (R-b) is challenging, as it requires detecting changes < 0.1 nm and in short fibers. By using a method based on four-wave mixing (FWM) generated by an incoherent-pump with relatively broad spectrum and a weak laser, we report measurements of lambda(0) as a function of Rb in a dispersion-shifted fiber with

We report phase-modulation mode-locking of a continuous-wave (cw) singlyresonant optical parametric oscillator (OPO) in the near- and mid-infrared based on MgO-doped periodically poled LiNbO3 (MgO:PPLN) and pumped by an Yb-fiber laser at 1064 nm. By investigating the spectral output and pulse formation characteristics of the OPO, we observe a clear transition from an unstable spectrum in cw operation to a stable and smooth profile under phase modulation, confirming mode-locked operation. Pulse generation and spectral characteristics under different operating conditions are studied, including the effects of the location of the intracavity phase modulator and the number of oscillating modes on mode-locked output pulse duration.

We report the generation of tunable high-repetition-rate picosecond radiation in the mid-infrared using the new quasi-phase-matched nonlinear material of orientation-patterned gallium phosphide (OP-GaP). The source is realized by single-pass difference-frequencygeneration (DFG) between the output signal of a picosecond optical parametric oscillator (OPO) tunable across 1609-1637 nm with input pump pulses at 1064 nm in OP-GaP, resulting in tunable radiation across 3040-3132 nm. Using a 40-mm-long crystal, we have generated up to 57 mW of DFG average power at ~80 MHz repetition rate for a pump power of 5 W and signal power of 0.9 W, with >30 mW over >50% of the tuning range. The DFG source exhibits a passive power stability better than 3.2% rms over 1 hour in good spatial beam quality. To the best of our knowledge, this is the first picosecond frequency conversion source based on OP-GaP

Quantum annealing aims at solving combinatorial optimization problems mapped to Ising interactions between quantum spins. Here, with the objective of developing a noise-resilient annealer, we propose a paradigm for quantum annealing with a scalable network of two-photon-driven Kerr-nonlinear resonators. Each resonator encodes an Ising spin in a robust degenerate subspace formed by two coherent states of opposite phases. A fully connected optimization problem is mapped to local fields driving the resonators, which are connected with only local four-body interactions. We describe an adiabatic annealing protocol in this system and analyse its performance in the presence of photon loss. Numerical simulations indicate substantial resilience to this noise channel, leading to a high success probability for quantum annealing. Finally, we propose a realistic circuit QED implementation of this promising platform for implementing a large-scale quantum Ising machine., Quantum annealing aims at solving optimization problems mapped to Ising interactions between neighbouring spins, but it is crucial to implement it in a noise-resilient way. Here the authors propose a network of all-to-all connected driven Kerr-nonlinear resonators, which exhibits high success probabilities.

We present efficient high-order harmonic generation (HHG) based on a high-repetition rate, few-cycle, near infrared (NIR), carrier-envelope phase stable, optical parametric chirped pulse amplifier (OPCPA), emitting 6fs pulses with 9{\mu}J pulse energy at 200kHz repetition rate. In krypton, we reach conversion efficiencies from the NIR to the extreme ultraviolet (XUV) radiation pulse energy on the order of ~10^{-6} with less than 3{\mu}J driving pulse energy. This is achieved by optimizing the OPCPA for a spatially and temporally clean pulse and by a specially designed high-pressure gas target. In the future, the high efficiency of the HHG source will be beneficial for high-repetition rate two-colour (NIR-XUV) pumpprobe experiments, where the available pulse energy from the laser has to be distributed economically between pump and probe pulses., Comment: 25 pages, 11 figures

Two-photon excitation (2PE) microscopy [1] has proven to be an excellent technique for in vivo fluorescence imaging of deep structures and tissues due to low absorption and scattering of infrared light. The combination of two laser beams introduces the possibility of further imaging capabilities, such as simultaneous excitation of three fluorophores (multiphoton-multicolor [2]) and sub-diffraction resolution of cellular structures (STimulated Emission Depletion, STED [3,4,5,6,7]). Here we present a cost-effective solution that combines both techniques by use of a homemade optical bench equipped with a pulsed laser split in two beams by an Optical Parametric Oscillator (OPO). Preliminary experiments were successfully performed with the multiphoton-multicolor technique, setting proper conditions to perform experiments for the study of neutrophil mobilization in skull bone marrow of diabetic mice. In the STED configuration, we successfully tested the fluorescence depletion effect and the optical generation of a doughnut-shaped point-spread-function by the depletion laser, both conditions required to obtain super-resolution. A preliminary super-resolution performance was obtained by visualizing the outer mitochondrial membrane stained with Alexa 647 dye.

Agradecimentos: The authors thank Nathan Newbury and Ian Coddington of NIST for discussions, and Dan Hickstein and Kevin Cossel of NIST for useful feedback on the manuscript. We acknowledge the support of NIST (including the Greenhouse Gas and Climate Science Measurement Program), the DARPA SCOUT program, and CNPq (Brazil). This work is a contribution of the US Government and is not subject to copyright in the United States. The mentioning of company and product names is for technical communication only and does not constitute an endorsement by NIST Abstract: A tunable mid-infrared frequency comb was created via difference frequency generation. Pulses between 1 and 1.5 µm were mixed to generate light ranging from 2.6 to 5.2 µm. Two such combs were heterodyned at 5 µm to show their coherence and potential for spectroscopy. The properties of the comb were modeled using numerical simulation, which confirmed the observed bandwidths CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ Fechado

We report an optical parametric generator (OPG) based on the new nonlinear material, orientation-patterned gallium phosphide (OP-GaP). Pumped by a 𝑄Q-switched nanosecond Nd:YAG laser at 1064 nm with 25 kHz pulse repetition rate, the OPG can be tuned across 1721–1850 nm in the signal and 2504–2787 nm in the idler. Using a 40-mm-long crystal in single-pass configuration, we have generated a total average output power of up to ∼18 mW∼18 mW, with ∼5 mW∼5 mW of idler power at 2670 nm, for 2 W of input pump power. The OPG exhibits a passive stability in total output power better than 0.87% rms over 1 h, at a crystal temperature of 120°C, compared to 0.14% rms for the input pump. The output signal pulses, recorded at 1769 nm, have duration of 5.9 ns for input pump pulses of 9 ns. Temperature-dependent loss measurements for the pump polarization along the [100] axis in the OP-GaP crystal have also been performed, for the first time, indicating a drop in transmission from 28.8% at 50°C to 19.4% at 160°C.

The supercritical complex Swift-Hohenberg equation models pattern formation in lasers, optical parametric oscillators and photorefractive oscillators. Simulations of this equation in one spatial dimension reveal that much of the observed dynamics can be understood in terms of the properties of exact solutions of phase-winding type. With real coefficients these states take the form of time-independent spatial oscillations with a constant phase difference between the real and imaginary parts of the order parameter and may be unstable to a longwave instability. Depending on parameters the evolution of this instability may or may not conserve phase. In the former case the system undergoes slow coarsening described by a Cahn-Hilliard equation; in the latter it undergoes repeated phase-slips leading either to a stable phase-winding state or to a faceted state consisting of an array of frozen defects connecting phase-winding states with equal and opposite phase. The transitions between these regimes are studied and their location in parameter space is determined.

We report a stable, Yb-fiber-laser-based, green-pumped, picosecond optical parametric oscillator (OPO) for the near-infrared based on periodically poled potassium titanyl phosphate (PPKTP) nonlinear crystal, using fan-out grating design and operating near room temperature. The OPO is continuously tunable across 726–955 nm in the signal and 1201–1998 nm in the idler, resulting in a total signal plus idler wavelength coverage of 1026 nm by grating tuning at a fixed temperature. The device generates up to 580 mW of average power in the signal at 765 nm and 300 mW in the idler at 1338 nm, with an overall extraction efficiency of up to 52% and a pump depletion >76%>76%. The extracted signal at 765 nm and idler at 1746 nm exhibit excellent passive power stability better than 0.5% and 0.8% rms, respectively, over 1 h with good beam quality in TEM00TEM00 mode profile. The output signal pulses have a Gaussian temporal duration of 13.2 ps, with a FWHM spectral bandwidth of 3.4 nm at 79.5 MHz repetition rate. Power scaling limitations of the OPO due to the material properties of PPKTP are studied.

Substitution of the halide ligands in (Bu4N)2[Mo3S7X6] (X = Cl, Br) by diimine ligands, such as 4,4′-dimethyl-2,2′-bipyridine (dmbpy), 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen), affords the neutral heteroleptic clusters Mo3S7Cl4(dmbpy) (1), Mo3S7Br4(dmbpy) (2), Mo3S7Br4(bpy) (3), and Mo3S7Br4(phen) (4). Further substitution of the halide ligands in Mo3S7Br4(diimine) clusters by dmit (1,3-dithiole-2-thione-4,5-dithiolate) allows the preparation of the mixed diimine–dithiolene neutral cluster complexes Mo3S7(dnbpy)(dmit)2 (5, dnbpy = 4,4′-dinonyl-2,2′-bipyridine), Mo3S7(dcmbpy)(dmit)2 (6, dcmbpy = 4,4′-dimethoxycarbonyl-2,2′-bipyridine), and Mo3S7(dcbpy)(dmit)2 (7, dcbpy = 2,2′-bipyridine-4,4′-dicarboxylic acid). The optical limiting properties of complexes 1–7 have been assessed by the open-aperture Z-scan technique at 570 nm, employing a nanosecond optical parametric oscillator. In order to investigate the effect of increasing the π-system, complexes 1–4, with the general formula Mo3S7X4(diimine), (X = Cl, Br), were compared to clusters 5–7, containing the dmit ligand. The influence of the metal content on the optical power limiting properties was also investigated by comparing the trinuclear series of complexes prepared herein with the bis(dithiolene) dinuclear cluster (Et4N)2[Mo2O2S2(BPyDTS2)2], which has been recently prepared by our group. All trinuclear clusters 1–7 are efficient optical limiters (σeff > σ0) with the threshold limiting fluence F15% decreasing on proceeding from dinuclear to trinuclear clusters and, generally, on extending the π-system. Financial support from the Spanish Ministerio de Economia y Competitividad (MINECO) (Grant CTQ2011-23157), UJI (research project P1.1B2013-19) and Generalitat Valenciana (Prometeo/2014/022 and ACOMP/2014/274) is gratefully acknowledged. The authors also thank Serveis Centrals d ’ Instrumentació Cientifica (SCIC), within Universitat Jaume, I for providing them with materials characterization facilities. D. R. thanks the Spanish Ministerio de Economía y Competividad for a predoctoral fellowship. M. G. H. thanks the Australian Research Council for support. M. S. acknowl- edges the NCN grant DEC-2013/10/A/ST4/00114

We propose and demonstrate a pump-phase locking technique that makes use of weak pump depletion (WPD) - an unavoidable effect that is usually neglected - in a sub-threshold optical parametric oscillator (OPO). We show that the phase difference between seed and pump beam is imprinted on both light fields by the non-linear interaction in the crystal and can be read out without disturbing the squeezed output. Our new locking technique allows for the first experimental realization of a pump-phase lock by reading out the pre-existing phase information in the pump field. There is no degradation of the detected squeezed states required to implement this scheme., Comment: 11 pages, 7 figures

The Berezinskii-Kosterlitz-Thouless mechanism, in which a phase transition is mediated by the proliferation of topological defects, governs the critical behavior of a wide range of equilibrium twodimensional systems with a continuous symmetry, ranging from spin systems to superconducting thin films and two-dimensional Bose fluids, such as liquid helium and ultracold atoms. We show here that this phenomenon is not restricted to thermal equilibrium, rather it survives more generally in a dissipative highly nonequilibrium system driven into a steady state. By considering a quantum fluid of polaritons of an experimentally relevant size, in the so-called optical parametric oscillator regime, we demonstrate that it indeed undergoes a phase transition associated with a vortex binding-unbinding mechanism. Yet, the exponent of the power-law decay of the first-order correlation function in the (algebraically) ordered phase can exceed the equilibrium upper limit: this shows that the ordered phase of driven-dissipative systems can sustain a higher level of collective excitations before the order is destroyed by topological defects. Our work suggests that the macroscopic coherence phenomena, observed recently in interacting twodimensional light-matter systems, result from a nonequilibrium phase transition of the Berezinskii- Kosterlitz-Thouless rather than the Bose-Einstein condensation type, M. H. S. acknowledges support from EPSRC (Grants No. EP/ I028900/2 and No. EP/K003623/2), F. M. M. from the programs Ministerio de Economia y Competitividad (No. MAT2011-22997) and Comunidad Autonoma de Madrid (No. S-2009/ESP-1503), and I. C. from ERC through the QGBE grant and from the Autonomous Province of Trento, partly through the project “On silicon chip quantum optics for quantum computing and secure communications” (“SiQuro”)

Agradecimentos: The authors thank William Loh and Richard Fox for comments on this manuscript, and also Nathan Newbury for discussions. We are grateful to M. Hirano of Sumitomo Electric Industries for providing optical fibers. We acknowledge the support of NIST (including the Greenhouse Gas and Climate Science Measurement Program) and the DARPA SCOUT program. FCC acknowledges Esther Baumann for discussions and loan of MIR optics, and also the support of CNPq, Fapesp, Fotonicom and UNICAMP. This paper is a contribution from the US government and is not subject to copyright in the US Abstract: Mid-infrared femtosecond optical frequency combs were produced by difference frequency generation of the spectral components of a near-infrared comb in a 3-mm-long MgO:PPLN crystal. We observe strong pump depletion and 9.3 dB parametric gain in the 1.5 mu m signal, which yields powers above 500 mW (3 mu W/mode) in the idler with spectra covering 2.8 mu m to 3.5 mu m. Potential for broadband, high-resolution molecular spectroscopy is demonstrated by absorption spectra and interferograms obtained by heterodyning two combs CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto

cited By 17; International audience; This paper presents a synthesis of some analytical potentialities of an equipment designed for both laser induced molecular and atomic fluorescence in the field of ultra-trace analysis (ng 1-1). Excitation of fluorescence was performed with a pulsed Nd:Yag laser coupled to an optical parametric oscillator (OPO). Fluorescence spectra were recorded with a spectrograph and an intensified charge-coupled device (ICCD). The high energy and the tunability of the excitation combined with the sensitivity of the ICCD and the time-resolution provide better limit of detection (LOD) and selectivity. By molecular fluorescence, some major organic contaminants in the environment were studied, i.e. polycyclic aromatic hydrocarbons (PAHs) (benzo[a]pyrene and hydroxypyrene) and a pesticide (carbaryl). The LODs achieved by direct analysis were far below the restricted European values for tap water. Analysis was performed in water containing humic acids using time resolution to avoid the matrix fluorescence. By electro thermal atomisation-laser excited atomic fluorescence (ETA-LEAF), we detected traces of aluminium and lead in seawater. Some general considerations about the signal to noise ratio optimisation are reported. LODs reached the femtogram level. © 2003 Elsevier Science B.V. All rights reserved.

cited By 13; International audience; The development of an analytical method for the direct determination of ultra trace content of aluminum in seawater by electrothermal atomization-laser excited atomic fluorescence (ETA-LEAF) using a pulsed Nd:Yag laser associated with an optical parametric oscillator (OPO) and an intensified CCD (ICCD) camera is described. The good temporal reproducibility of the device and the fairly long lifetime of the selected Al radiation allowed optimization of the temporal parameters in the nanosecond range. After optimizing thermal and optical parameters, this potentiality allowed to reach a 100 fg detection limit (5 ng l-1). The method was developed within a multidisciplinary program involving chemical and physical applications, thereby demonstrating the versatility of the apparatus. © 2002 Elsevier Science B.V. All rights reserved.

We report a continuous-wave (cw) source of tunable mid-infrared radiation providing tens of milliwatt of output power in the 6460–7517 nm spectral range. The source is based on difference-frequency generation (DFG) in orientation-patterned (OP)-GaAs pumped by a Tm-fiber laser at 2010 nm and a 1064 nm-Yb-fiber-pumped cw optical parametric oscillator. Using a 25.7-mm-long OP-GaAs crystal, we have generated up to 51.1 mW of output power at 6790 nm, with >40 mW and >20 mW across 32% and 80% of the mid-infrared tuning range, respectively, which is to the best of our knowledge the highest tunable cw power generated in OP-GaAs in this spectral range. The DFG output at maximum power exhibits passive power stability better than 2.3% rms over more than 1 h and a frequency stability of 1.8 GHz over more than 1 min, in high spatial beam quality. The system and crystal performance at high pump powers have been studied

We report a few-cycle, broadband, singly-resonant optical parametric oscillator (OPO) for the mid-infrared based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN), synchronously pumped by a 20-fs Ti:sapphire laser. By using crystal interaction lengths as short as 250 um, and careful dispersion management of input pump pulses and the OPO resonator, near-transform-limited, few-cycle idler pulses tunable across the mid-infrared have been generated, with as few as 3.7 optical cycles at 2682 nm. The OPO can be continuously tuned over 2179-3732 nm by cavity delay tuning, providing up to 33 mW of output power at 3723 nm. The idler spectra exhibit stable broadband profiles with bandwidths spaning over 422 nm (FWHM) recorded at 3732 nm. We investigate the effect of crystal length on spectral bandwidth and pulse duration at a fixed wavelength, confirming near-transform-limited idler pulses for all grating interaction lengths. By locking the repetition frequency of the pump laser to a radio-frequency reference, and without active stabilization of the OPO cavity length, an idler power stability better than 1.6% rms over >2.75 hours is obtained when operating at maximum output power, in excellent spatial beam quality with TEM00 mode profile., 12 pages, 8 figures

We theoretically demonstrate a novel approach for generating Mid-InfraRed SuperContinuum (MIR SC) by using concatenated fluoride and chalcogenide glass fibers pumped with a standard pulsed Thulium (Tm) laser (TFWHM=3.5ps, P0=20kW, νR=30MHz, and Pavg=2W). The fluoride fiber SC is generated in 10m of ZBLAN spanning the 0.9–4.1μm SC at the −30dB level. The ZBLAN fiber SC is then coupled into 10cm of As2Se3 chalcogenide Microstructured Optical Fiber (MOF) designed to have a zero-dispersion wavelength (λZDW) significantly below the 4.1μm InfraRed (IR) edge of the ZBLAN fiber SC, here 3.55μm. This allows the MIR solitons in the ZBLAN fiber SC to couple into anomalous dispersion in the chalcogenide fiber and further redshift out to the fiber loss edge at around 9μm. The final 0.9–9μm SC covers over 3 octaves in the MIR with around 15mW of power converted into the 6–9μm range.

For the CO2 and CH4 IPDA lidar CHARM-F two single frequency Nd:YAG based MOPA systems were developed. Both lasers are used for OPO/OPA-pumping in order to generate laser radiation at 1645 nm for CH4 detection and 1572 nm for CO2 detection. By the use of a Q-switched, injection seeded and actively length-stabilized oscillator and a one-stage INNOSLAB amplifier about 85 mJ pulse energy could be generated for the CH4 system. For the CO2 system the energy was boosted in second INNOSLAB-stage to about 150 mJ. Both lasers emit laser pulses of about 30 ns pulse duration at a repetition rate of 100 Hz.

We present a theoretical and experimental analysis of a pulsed 1645 nm optical parametric oscillator (OPO) conducted to prove the feasibility of such a device for a spaceborne laser transmitter in an integrated path differential absorption (IPDA) lidar system. The investigation is part of the French-German satellite mission MERLIN (Methane Remote Sensing Lidar Mission). As an effective greenhouse gas, methane plays an important role for the global climate. The architecture of the OPO is based on a conceptual design developed by DLR, consisting of two KTA crystals in a four-mirror-cavity. One of the cavity mirrors is piezo-driven to provide single frequency operation of the OPO. Using numerical simulations, we studied the performance and alignment tolerances of such a setup with KTP and KTA and investigated means to optimize the optical design by increasing the efficiency and decreasing the fluence on the optical components. For the experimental testing of the OPO, we used the INNOSlab-based ESA pre-development model ATLAS as pump laser at 1064 nm. At a pulse frequency of 25 Hz this MOPA delivers a pump energy up to 45 mJ with a beam quality factor of about M² = 1.3. With KTP as nonlinear crystal the OPO obtained 9.2 mJ pulse energy at 1645 nm from 31.5 mJ of the pump and a pump pulse duration of 42 ns. This corresponds to an optical/optical efficiency of 29%. After the pump pulse was reduced to 24 ns a similar OPO performance could be obtained by adapting the pump beam radius.

Agradecimentos: The authors acknowledge partial support from a FP7-EURAMET grant (contract No ENV-06). M. P. Moreno thanks CAPES for postdoctoral fellowship support under BEX-12610-12-7. The authors thank PHC-Capes Cofecub program (project code: 25060RE) for support Abstract: We report on absolute line strength measurements of P(1), R(0) and R(1) singlet lines in the (C-H stretching) band of methane at reference temperature K. Line strength measurements are performed at low pressure using direct absorption spectroscopy technique based on a widely tunable continuous-wave singly resonant optical parametric oscillator. The overall accuracy in line strength determinations ranges between 7 and 8 % mostly limited by pressure and frequency measurements. A comparison with previous reported values is made. Our results show good agreement with the HITRAN 2012 database COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado

Carbon dioxide (CO2) and methane (CH4) are the most important of the greenhouse gases that are directly influenced by human activities. The Integrated Path Differential Absorption (IPDA) lidar technique using hard target reflection in the near IR (1.57μm and 1.64μm) to measure the column-averaged dry air mixing ratio of CO2 and CH4 with high precision and low bias has the potential to deliver measurements from space and air that are needed to understand the sources and sinks of these greenhouse gases. CO2 and CH4 IPDA require tunable laser sources at 1.57 μm and 1.64 μm that coincide with appropriate absorption lines of these species having high pulse energy and average power as well as excellent spectral and spatial properties. Within this study we have realized more than 50mJ of pulse energy in the near IR coincident with appropriate absorption lines using an injection-seeded optical parametric oscillator-amplifier system pumped at 100 Hz. At the same time this device showed excellent spectral and spatial properties. Bandwidths of less than 100 MHz with a high degree of spectral purity (> 99.9 %) have been achieved. The frequency stability was likewise excellent. The M2-factor was better than 2.3. Owing to these outstanding properties optical parametric devices are currently under investigation for the CH4 lidar instrument on the projected French-German climate satellite MERLIN. A similar device is under development at DLR for the lidar demonstrator CHARM-F which will enable the simultaneous measurement of CO2 and CH4 from an airborne platform.

PACS number(s): 05.45.-a, 47.54.-r, 47.55.D, The complex Swift-Hohenberg equation models pattern formation arising from an oscillatory instability with a finite wave number at onset and finds applications in lasers, optical parametric oscillators, and photorefractive oscillators. We show that with real coefficients this equation exhibits two classes of localized states: localized in amplitude only or localized in both amplitude and phase. The latter are associated with phase-winding states in which the real and imaginary parts of the order parameter oscillate periodically but with a constant phase difference between them. The localized states take the form of defects connecting phase-winding states with equal and opposite phase lag, and can be stable over a wide range of parameters. The formation of these defects leads to faceting of states with initially spatially uniform phase. Depending on parameters these facets may either coarsen indefinitely, as described by a Cahn-Hilliard equation, or the coarsening ceases leading to a frozen faceted structure., This work was funded by the Belgian Science Policy Office under Grant No. IAP-VI10. Support from the Research Foundation–Flanders (L.G.) and from the National Science Foundation under Grant No. DMS-0605238 (E.K.) is gratefully acknowledged. We thank J. Burke, S. Houghton, and U. Thiele for helpful discussions and a referee for bringing several references to our attention.

The nonlinear recovery of quantum dot based reverse-biased waveguide absorbers is investigated both experimentally and analytically. We show that the recovery dynamics consists of a fast initial layer followed by a relatively slow decay. The fast recovery stage is completely determined by the intradot properties, while the slow stage depends on the escape from the dot to the wetting layer.

We study the implementation of a correlation measurement technique for the characterization of squeezed light which is nearly free of electronic noise. With two different sources of squeezed light, we show that the sign of the covariance coefficient, revealed from the time resolved correlation data, is witnessing the presence of squeezing in the system. Furthermore, we estimate the degree of squeezing using the correlation method and compare it to the standard homodyne measurement scheme. We show that the role of electronic detector noise is minimized using the correlation approach as opposed to homodyning where it often becomes a crucial issue.

Infrared spectra of Ne-C2D2 are observed in the region of the ν3 fundamental band (asymmetric C-D stretch, ≈2440 cm(-1)) using a tunable optical parametric oscillator to probe a pulsed supersonic slit jet expansion from a cooled nozzle. Like helium-acetylene, this system lies close to the free rotor limit, making analysis tricky because stronger transitions tend to pile up close to monomer (C2D2) rotation-vibration transitions. Assignments are aided by predicted rotational energies calculated from a published ab initio intermolecular potential energy surface. The analysis extends up to the j = 3←2 band, where j labels C2D2 rotation within the dimer, and is much more complete than the limited infrared assignments previously reported for Ne-C2H2 and Ne-C2HD. Two previous microwave transitions within the j = 1 state of Ne-C2D2 are reassigned. Coriolis model fits to the theoretical levels and to the spectrum are compared. Since the variations observed as a function of C2D2 vibrational excitation are comparable to those noted between theory and experiment, it is evident that more detailed testing of theory will require vibrational averaging over the acetylene intramolecular modes.

Date of Conference: 14 July 2005 We report a 1064-nm pumped optical parametric oscillator based on a single KTiOAsO4 crystal that simultaneously generates the sum frequency of the pump and signal wavelengths, providing a 627 nm output with a high conversion efficiency.

8 pages, 8 figures.-- PACS nrs.: 42.65.Sf, 89.75.Kd, 05.65.+b, 42.70.Qs.-- ArXiv pre-print available: http://arxiv.org/abs/nlin/0503065v1, We study the inhibition of pattern formation in nonlinear optical systems using intracavity photonic crystals. We consider mean-field models for singly and doubly degenerate optical parametric oscillators. Analytical expressions for the new (higher) modulational thresholds and the size of the band gap as a function of the system and photonic crystal parameters are obtained via a coupled-mode theory. Then, by means of a nonlinear analysis, we derive amplitude equations for the unstable modes and find the stationary solutions above threshold. The form of the unstable mode is different in the lower and upper parts of the band gap. In each part there is bistability between two spatially shifted patterns. In large systems stable wall defects between the two solutions are formed and we provide analytical expressions for their shape. The analytical results are favorably compared with results obtained from the full system equations. Inhibition of pattern formation can be used to spatially control signal generation in the transverse plane., We acknowledge financial support from EPSRC (Grant Nos. GR S28600/1 and GR R04096/01), SGI, the Royal Society, Leverhulme Trust, and the European Commission (FunFACS).

7 pages, 11 figures., Two kinds of cavity solitons, stable circular domain walls (droplets) and dark ring cavity solitons, are presented in models of vectorial Kerr resonators and degenerate optical parametric oscillators. These structures are universal in systems with two equivalent homogeneous states and are found for parameter values close to those of a modulational instability of a flat front. We show that stable droplets nucleate out of dark ring cavity solitons and that in some systems there are regimes in which they coexist., This work was supported by the EC Networks QSTRUCT (FMRXCT960077) and QUANTIM (IST-2000-26019), and by the European Science Foundation network PHASE. The work of D. Gomlia, P. Colet, and M. San Miguel was supported by MCyT, Spain, under Project PB97-0141-C02-02 and Project BFM2000-1108. The work of A. J. Scroggie and G.-L. Oppo was supported by the EPSRC under Grant M19727, Grant M31880, and Grant R04096. The work of G.-L. Oppo was supported in part by SGI.

Summary form only given. In this experiment, we construct a self-doubling optical parametric oscillator (SDOPO). It is based on a LiNbO/sub 3/ crystal that has a one-dimensional aperiodic grating structure. This grating structure is designed to quasi-phase-match both optical parametric oscillation (OPO) and second harmonic generation (SHG) processes simultaneously for a propagation direction along the x-axis of the crystal. When a beam at a wavelength of 790 nm pumps the SDOPO, a signal beam at a wavelength of 1140 nm and an idler beam at a wavelength of 2573 nm are generated along with the SHG of the signal beam at a wavelength of 570 nm. Waves corresponding to both interactions are polarized parallel to the c-axis of the crystal in order to utilize the highest nonlinear coefficient, d/sub 33/.

cited By 11; International audience; Fluorescence was induced by coupling a laser with an optical parametric oscillator (OPO) to develop an analytical method for the direct determination of lead content, at ultra-trace level, in seawater by electrothermal atomization-laser-excited atomic fluorescence (ETA-LEAF). The optimization of atomization conditions, laser pulse energy, and mainly temporal parameters allowed us to reach a 3 fg detection limit (0.3 ng L-1) despite the low repetition rate of the device. The expected error on predicted concentrations of lead, at trace levels, in seawater was below 15%. © Springer-Verlag 2003.

Triply resonant optical parametric oscillations (TRO) are of interest for generating stable and highly correlated twin beams. Here we report intensity noise correlation and single beam spectra for pump powers up to 14 times the threshold value. The correlation spectrum appear to be independent of the pump power while the single beams exhibit a peak due to relaxation oscillation. Such a resonance contributes to mask the squeezing predicted for double resonant devices. The herein discussed TRO has shown a temporal stability of the pump resonance longer than 6 h while delivering up to 4 mW per beam, fluctuating less than 5% over periods longer than half an hour.

Date of Conference: 18-21 November 1996 Conference Name: 9th Annual Meeting IEEE Lasers and Electro-Optics Society, LEOS 1996 A new self-doubling optical parametric oscillator (OPO) uses a single nonlinear crystal for both parametric generation and frequency doubling. It is based on a KTiOPO4 (KTP) crystal pumped by a Ti:Sapphire laser operating at a wavelength of 739 nm. The crystal is cut such that the signal wavelength of the OPO is at 1064 nm, corresponding to an idler wavelength of 2420 nm. The OPO cavity resonates only the signal wavelength. The signal beam is also phase-matched for second harmonic generation (SHG) at the same crystal orientation. With proper polarization rotation, an output beam at a wavelength of 532 nm can be obtained.