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Squeezed vacuum is a versatile resource of bipartite entanglement for quantum metrology and information. Optical parametric oscillators generate these states in a frequency comb structure. We show the simultaneous detection of 18 teeth with 11 dB of squeezing each. We built a 1.5-m-long optical resonator to increase the spectral teeth density and significantly increase the detection bandwidth by employing unbalanced homodyne detection instead of balanced. Our approach can be a crucial step in using the scaling potential of high-frequency squeezed states in quantum information.

© 2004 The American Physical Society. This work was supported by Project No. BFM2000-0796 (Spain). We are very grateful to M. Ritsch-Marte and J. Lega for their helpful advice., Phase domains and phase solitons in two-level amplifying media damped by a squeezed vacuum are predicted for the first time. Two different types of pattern formation are found depending on the relative value of the cavity detuning to the squeezed parameter: the usual one in lasers via a supercritical Hopf bifurcation and a new one via pitchfork bifurcation., Ministerio de Ciencia y Tecnología (MCYT), España, Ministerio de Ciencia e Innovación (MINECO), España, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Broadband tunable femtosecond laser pulses are of great interest in numerous fields, such as spectroscopy or imaging. Here, we report on the generation of rapidly tunable radiation in the near UV by using intracavity non-collinear sum-frequency mixing between the visible pulses of a non-collinear optical parametric oscillator (NOPO) and a near-infrared beam. The NOPO is pumped by the third harmonic of an Yb-based master oscillator fiber amplifier (MOFA). For sum-frequency mixing, remaining fundamental pulses at 1030 nm are used. With this approach, near-UV pulses in a range of 333-413 nm with average output powers up to 90mW and pulse durations from 158-240 fs are achieved. Fast tunability is demonstrated over the whole tuning range by varying just the cavity length. The system also allows for the generation of two simultaneous synchronized output pulse trains in the visible and the near-UV spectral range.

We present a quantum theory of nondegenerate phase-sensitive parametric amplification in a ?(3) nonlinear medium. The nonzero response time of the Kerr (?(3)) nonlinearity determines the quantum-limited. noise figure of the ?(3) parametric amplification, as well as the limit on quadrature squeezing. This nonzero response time of the nonlinearity requires coupling of the parametric process to a molecular vibration phonon bath, causing the addition of excess noise through spontaneous Raman scattering. We present analytical expressions for the quantum-limited noise figure of frequency nondegenerate and frequency degenerate ?(3) parametric amplifiers operated as phase-sensitive amplifiers. We also present results for frequency nondegenerate quadrature squeezing. We show that our nondegenerate squeezing theory agrees with the degenerate squeezing theory of Boivin and Shapiro as degeneracy is approached. We have also included the effect of linear loss on the phase-sensitive process. © 2006 Optical Society of America.

We present a quantum theory of nondegenerate phase-sensitive parametric amplification in a ?(3) nonlinear medium. The nonzero response time of the Kerr (?(3)) nonlinearity determines the quantum-limited. noise figure of the ?(3) parametric amplification, as well as the limit on quadrature squeezing. This nonzero response time of the nonlinearity requires coupling of the parametric process to a molecular vibration phonon bath, causing the addition of excess noise through spontaneous Raman scattering. We present analytical expressions for the quantum-limited noise figure of frequency nondegenerate and frequency degenerate ?(3) parametric amplifiers operated as phase-sensitive amplifiers. We also present results for frequency nondegenerate quadrature squeezing. We show that our nondegenerate squeezing theory agrees with the degenerate squeezing theory of Boivin and Shapiro as degeneracy is approached. We have also included the effect of linear loss on the phase-sensitive process. © 2006 Optical Society of America.

The creation of the periodical domain patterns with a submicron period in lithium niobate on insulator (LNOI) wafers is a key problem for nonlinear-optical applications, including second harmonic generation, backscattering optical parametric oscillator, etc. We have experimentally studied the domain formation and evolution during local polarization reversal in Z+ LNOI wafers with a metal bottom electrode. It has been shown that domain growth occurs by the formation of the spikes at the charged domain wall (CDW). The complicated shape of isolated domains with a jagged CDW has been revealed. The obtained weak domain-domain interaction has been attributed to effective bulk screening by charge injection. The revealed dependence of the domain sizes on humidity caused by the adsorbed water layer should be taken into account during periodical poling. © 2020 Author(s).

We report a green-pumped continuous-wave OPO using a fanout-grating MgO:PPLN, tunable across 813-1032 nm (signal) and 1098-1539 nm (idler) with >30% extraction efficiency in excellent beam-quality and power stability better than 3% rms over 1 hour., Peer Reviewed, Postprint (published version)

Efficient, diode-pumped high energy femtosecond laser systems around 1 µm based on Yb-gain media are readily commercially available. However, owing to the gain bandwidth limitations, the pulses generated in such lasers are substantially longer than the ones generated in Ti:Sapphire systems. A simple, energy-scalable pulse self-compression scheme for the pulses around 1 µm thus would be of great interest for many applications, including time-resolved pump-probe spectroscopy, high-harmonics generation, etc. The self-phase modulation during nonlinear propagation in filaments in gasses is often employed for pulse self-compression [1,2]. Such schemes typically require rather bulky setups and careful control of group velocity dispersion. Some years ago it has been shown theoretically that Raman-active molecules in gaseous form could be used for mid-infrared pulse compression [3]., QC 20200623

Optical parametric oscillators (OPOs) based on AgGaSe2 and BaGa2GeSe6, and difference-frequency generation (DFG) in AgGaSe2 and BaGa4Se7 are studied inside the cavity of an oxide-crystal-based OPO to produce widely-tunable mid-IR radiation in the 4.4-18-µm range., QC 20200617

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.

A mirrorless optical parametric oscillator (MOPO) is a very special class of optical parametric oscillators, where the feedback for oscillation is realized by counter-propagating second-order nonlinear interaction without a need for external mirrors. This arrangement makes the MOPO a very simple, self-aligned and robust oscillator. The MOPO was first proposed theoretically in 1966 [1] however its realization was only possible using the quasi-phase matching (QPM) approach due to requirement for compensation of large momentum mismatch in such interactions [2]. Realization of first-order counter-propagating parametric oscillation requires structures with periodicity in the sub-µm range, which poses substantial fabrication challenges. In addition to its self-aligned nature, MOPO offers unique spectral properties [3], whereby the spectral contents of the pump are transferred to the forward wave, while the backward wave remains narrowband. So far, only nondegenerate MOPO oscillation has been demonstrated. However, it has been theoretically proposed that a degenerate MOPO could be used to realize a high-brightness biphoton source for quantum optics applications [4]., SyskonpostNot duplicate with DiVA 1379157Part of proceedings: ISBN 978-1-7281-0469-0QC 20230925

Optical frequency comb sources based on quadratic nonlinearities provide an interesting alternative to Kerr combs in terms of reduced pump power requirements and extended spectral coverage. We review theory and recent experiments of quadratic optical frequency combs based on second-harmonic generation and optical parametric oscillation., info:eu-repo/semantics/published

We report a high-repetition-rate femtosecond optical parametric oscillator (OPO) for the deep-infrared (deep-IR) based on the nonlinear optical crystal, CdSiP 2 (CSP), pumped directly by a Ti:sapphire laser, for the first time. By pumping CSP at <;1 μm, we have achieved practical output powers at the longest wavelengths generated by any Ti:sapphire-pumped OPO. Using a combination of pump wavelength tuning, type-I critical phase matching, and cavity delay tuning, we have generated continuously tunable radiation across 6654-8373 nm (1194-1503 cm -1 ) at 80.5-MHz repetition rate, providing up to 20 mW of average power at 7314 nm and >7 mW beyond 8000 nm, with idler spectra exhibiting bandwidths of 140-180 nm across the tuning range. Moreover, the near-IR signal is tunable across 1127-1192 nm, providing up to 37 mW of average power at 1150 nm. Signal pulses, characterized using intensity autocorrelation, have durations of ~260-320 fs, with corresponding time-bandwidth product of ΔυΔτ ~ 1. The idler and signal output exhibit a TEM00 spatial profile with single-peak Gaussian distribution. With an equivalent spectral brightness of ~6.68 × 10 20 photons s -1 mm -2 sr -1 0.1% BW -1 , this OPO represents a viable alternative to synchrotron and supercontinuum sources for deep-IR applications in spectroscopy, metrology, and medical diagnostics., Peer Reviewed, Postprint (author's final draft)

We describe a degenerate 1.064-μm-pumped pulsed optical parametric oscillator based on MgO:PPLN in compact Littrow-grating cavity configuration, providing 2.7W of average power at 2.1μm with high spectral and power stability in good spatial beam quality., Peer Reviewed, Postprint (author's final draft)

We report on the development of high-average-power nanosecond and picosecond laser sources tunable near 2 μm based on optical parametric oscillators (OPOs) pumped by solid-state Nd:YAG and Yb-fiber lasers at 1.064 μm. By exploiting 50-mm-long MgO-doped lithium niobate (MgO:PPLN) as the nonlinear crystal and operating the OPO in a near-degenerate doubly resonant configuration with intracavity wavelength selection elements, we have generated tunable high-average-power radiation across 1880–2451 nm in high spectral and spatial beam quality with excellent output stability. In nanosecond operation, pumping with a Q-switched Nd:YAG laser and using an intracavity prism for spectral control, we have generated more than 2 W of average power in pulses of 10 ns duration at 80 kHz repetition rate with narrow linewidth (<3 nm), with M2 < 2.8, and a passive power stability better than 2.2% rms over 1 h. In picosecond operation, pumping with a mode-locked Ybfiber laser and using a diffraction grating as the wavelength selection element, we have generated more than 5 W of average power in pulses of 20 ps at 80 MHz repetition rate with narrow bandwidth (∼2.5 nm), with M2 < 1.8 and a passive power stability better than 1.3% rms over 2 h. The demonstrated sources represent viable alternatives to Tm3 ∕Ho3 -doped solid-state and fiber lasers for the generation of high-power radiation in the ∼2 μm spectral range., Peer Reviewed, Postprint (author's final draft)

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., Peer Reviewed, Postprint (author's final draft)

we report the first measurements of angular quasi-phase-matching directions of secondharmonic generation performed in the periodically-poled Rb-doped KTiOPO4 biaxial crystal cut as a sphere., QC 20181025

The gadolinium vanadate doped with samarium (GdVO 4 :Sm 3+ ) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve the full crystallinity, the material was annealed in air atmosphere at 900°C. Phase identification in the postannealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscopy (SEM). Photoluminescence characterization of the emission spectrum and time-resolved analysis have been performed using the tunable laser optical parametric oscillator excitation and the streak camera. Several strong emission bands in the Sm 3+ emission spectrum were observed, located at 567 nm ( 4 G 5/2 – 6 H 5/2 ), 604 nm ( 4 G 5/2 – 6 H 7/2 ), and 646 (654) nm ( 4 G 5/2 – 6 H 9/2 ), respectively. The weak emission bands at 533 nm ( 4 F 3/2 – 6 H 5/2 ) and 706 nm ( 4 G 5/2 – 6 H 11/2 ) and a weak broad luminescence emission band of VO 4 3− were also observed by the detection system. We analyzed the possibility of using the host luminescence for two-color temperature sensing. The proposed method is improved by introducing the temporal dependence in the line intensity ratio measurements.

The gadolinium vanadate doped with samarium (GdVO 4 :Sm 3+ ) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve the full crystallinity, the material was annealed in air atmosphere at 900°C. Phase identification in the postannealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscopy (SEM). Photoluminescence characterization of the emission spectrum and time-resolved analysis have been performed using the tunable laser optical parametric oscillator excitation and the streak camera. Several strong emission bands in the Sm 3+ emission spectrum were observed, located at 567 nm ( 4 G 5/2 – 6 H 5/2 ), 604 nm ( 4 G 5/2 – 6 H 7/2 ), and 646 (654) nm ( 4 G 5/2 – 6 H 9/2 ), respectively. The weak emission bands at 533 nm ( 4 F 3/2 – 6 H 5/2 ) and 706 nm ( 4 G 5/2 – 6 H 11/2 ) and a weak broad luminescence emission band of VO 4 3− were also observed by the detection system. We analyzed the possibility of using the host luminescence for two-color temperature sensing. The proposed method is improved by introducing the temporal dependence in the line intensity ratio measurements.

We report a high-repetition-rate femtosecond optical parametric oscillator (OPO) for the deep-infrared (deep-IR) based on type-I critical phase-matching in CdSiP2 (CSP), pumped directly by a Ti:sapphire laser. Using angle-tuning in the CSP crystal, the OPO can be continuously tuned across 7306–8329 nm (1201–1369 cm−1) in the deep-IR. It delivers up to 18 mW of idler average power at 7306 nm and >7 mW beyond 8000 nm at 80.5 MHz repetition rate, with the spectra exhibiting bandwidths of >150 nm across the tuning range. Moreover, the signal is tunable across 1128–1150 nm in the near-infrared, providing up to 35 mW of average power in ∼266 fs pulses at 1150 nm. Both beams exhibit single-peak Gaussian distribution in TEM00 spatial profile. With an equivalent spectral brightness of ∼5.6×1020photons s−1 mm−2 sr−10.1% BW−1, this OPO represents a viable alternative to synchrotron and supercontinuum sources for deep-IR applications in spectroscopy, metrology, and medical diagnostics., Peer Reviewed, Postprint (author's final draft)

A singly-resonant OPO (SRO) based on AgGaSe2 (AGSe) intracavity pumped at ∼1.85 μm by the signal pulses of a Rb:PPKTP doubly-resonant OPO (DRO) provided extremely broad tuning (5.8 to ∼18 μm) for the non-resonated idler. In a similar set-up with the same nonlinear crystals, we studied intracavity difference-frequency generation (DFG). Both AGSe and the new monoclinic crystal BaGa4Se7 (BGSe) generated single pulse energies of ∼0.7 mJ near 7 μm at an overall conversion efficiency from the 1.064 μm pump of 1.2%. The main advantage of BGSe is its damage resistivity up to the maximum pump levels applied at 100 Hz., QC 20171030

We report the first deep-infrared femtosecond OPO based on CdSiP2 synchronously-pumped directly by a KLM Ti:sapphire laser, tunable across 7508-8210 nm, and generating as much as 12 mW at 7508 nm in good beam-quality., Peer Reviewed, Postprint (author's final draft)

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, Peer Reviewed, Postprint (published version)

Controlled switching of orbital angular momentum (OAM) of light at practical powers over arbitrary wavelength regions can have important implications for future quantum and classical systems. Here we report on a single source of OAM beams based on an optical parametric oscillator (OPO) that can provide all such capabilities. We demonstrate active transfer of OAM modes of any order, jl pj, of pump to the signal and idler in an OPO, to produce jl pj1 different OAM states by controlling the relative cavity losses of the resonated beams. As a proof-of-principle, we show that when pumping with the OAM states jl pj 1 and jl pj 2 for different relative losses of signal and idler, the OPO has two (j1;0i and j0;1i) and three (j2;0i, j1;1i, and j0;2i) output states, respectively. Our findings show that using a suitable loss modulator, one can achieve rapid switching of the OAM mode in OPO output beams in time. ©, Peer Reviewed, Postprint (published version)

We report the first realization of a stable, room-temperature, green-pumped cw OPO using fan-out-grating MgO:sPPLT, providing rapid, continuous and wide-tuning across 734-1929nm, 2.2W of output-power, frequency-stability of 518MHz (2mins.) and linewidth of 6.9MHz, in good-beam-quality., Peer Reviewed, Postprint (author's final draft)

We report on a high-power femtosecond optical parametric oscillator (OPO) at 80 MHz repetition rate, tunable across 6318–7061 nm in the deep-infrared (deep-IR) using pump wavelength tuning. The OPO, based on CdSiP2CdSiP2 (CSP), is synchronously pumped by a commercial Ti:sapphire-pumped femtosecond OPO in the near-IR, enabling rapid static tuning of the CSP OPO with minimal adjustments to its cavity length. The deep-IR CSP OPO provides as much as 32 mW of average idler power at 6808 nm with spectral bandwidth >1000 nm>1000 nm (at −10 dB−10 dB level) across the tuning range. By implementing intracavity dispersion control, near-transform-limited signal pulses of ∼100 fs∼100 fs duration with smooth single-peak spectrum are achieved at 1264 nm, corresponding to an idler wavelength at 6440 nm. To the best of our knowledge, this is the first time such practical idler powers in the deep-IR have been generated from a dispersion-compensated CSP femtosecond OPO at sub-100 MHz repetition rate., Peer Reviewed, Postprint (author's final draft)

We report on a femtosecond optical parametric oscillator (OPO) for the deep-infrared (deep-IR) based on the Kerr-lens-mode-locked Ti:sapphire laser as the pump source. By deploying a novel cascaded intracavity arrangement, comprising a femtosecond OPO based on the nonlinear crystal, CdSiP2CdSiP2, synchronously pumped internal to a MgO:PPLN femtosecond OPO, we have generated broadly tunable radiation across 5958–8117 nm using rapid static cavity delay tuning, with a maximum power of 64 μW at 6791 nm, limited by the absorption in mirror substrates as well as polarization-dependent intracavity losses. The deep-IR idler power exhibits excellent passive stability of better than 1.1% rms over 2 h, with a spectral bandwidth as large as ∼650 nm∼650 nm at ∼6800 nm∼6800 nm. The demonstrated concept is generic and can be similarly deployed in other operating time scales and wavelength regions, also using different laser pump sources and nonlinear materials., Peer Reviewed, Postprint (author's final draft)

A 1.064 mu m pumped Rb:PPKTP optical parametric oscillator (OPO) generates mid-IR radiation by intracavity mixing the resonant signal and idler waves in AgGaSe2. The similar to 6 ns pulses at similar to 7 mu m have an energy of 670 mu J at 100 Hz, equivalent to an average power of 67 mW. The overall quantum conversion efficiency from 1.064 mu m amounts to 8%, and the power conversion efficiency is 1.2%., QC 20160715

We report on a AgGaSe2 optical parametric oscillator (OPO), intracavity pumped by the 1.85-μm signal pulses of a 1.064-μm pumped Rb:PPKTP OPO. It operates at 100 Hz with idler tunability from ~8 to 18 μm., Conference code: 133858; Export Date: 22 May 2017; Conference Paper; Correspondence Address: Petrov, V.; Max-Born-Institute for Nonlinear Optics and Ultrafast Spectroscopy, 2A Max-Born-Str., Germany; email: petrov@mbi-berlin.de. QC 20170607

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., Peer Reviewed, Postprint (author's final draft)

We report a femtosecond optical parametric oscillator (OPO) for the mid-infrared (mid-IR), generating a record average power of 110 mW at 7 μm. The OPO, based on CdSiP2 (CSP) as the nonlinear crystal, provides idler wavelength tuning across 6540–7186 nm with spectral bandwidths >400 nm at −10 dB level over the entire range, and a maximum bandwidth of 478 nm at 6.9 μm. To the best of our knowledge, this is the highest average power generated from a femtosecond OPO in the deep mid-IR. The OPO also provides near-IR signal wavelengths tunable across 1204–1212 nm with a usable power of 450 mW in 418-fs pulses at 1207 nm. The simultaneously measured signal and idler power exhibit a passive stability better than 1.6% rms and 3% rms, respectively. A mid-IR idler spectral stability with a standard deviation of the frequency fluctuations better than 40 MHz over 15 min, limited by the measurement resolution, is realized. Using the mid-IR idler from the CSP OPO, we perform Fourier-transform spectroscopy to detect liquid phase organic solvent, toluene (C7H8), in the molecular fingerprint region., Postprint (author’s final draft)

We report on an AgGaSe2 optical parametric oscillator (OPO), intracavity pumped by the 1.85-μm signal pulses from a 1.064-μm pumped Rb:PPKTP OPO. It operates at 100 Hz with idler tunability from 5.8 to 8.3 μm., QC 20160203

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. In our experimental setup we observe squeezing levels of 1.96±0.01 dB, with an anti-squeezing level of 3.78±0.02dB (for a 0.55mW seed beam at 1064nm and 67.8 mW of pump light at 532 nm). 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. © 2015 Optical Society of America.

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., Peer Reviewed, Postprint (published version)

We demonstrate a femtosecond optical parametric oscillator based on two nonlinear crystals synchronously pumped by a single ultrafast laser for efficient intracavity signal amplification and output power enhancement. By deploying two identical MgO:PPLN crystals in a single standing-wave cavity, and two pump pulse trains of similar average power from the same Kerr-lens-mode-locked Ti:sapphire laser, a minimum enhancement of 56% in the extracted signal power is achieved, with un-optimized output coupling, when temporal synchronization between the two intracavity signal pulse trains is established, resulting in a corresponding enhancement of 49% in pump depletion. Using intracavity dispersion control, near-transform-limited signal pulses with clean spectrum are obtained, Peer Reviewed, Preprint

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, Postprint (published version)

A few-cycle, broadband, singly-resonant optical parametric oscillator (OPO) for the mid-infrared based on MgOdoped periodically-poled LiNbO3 (MgO:PPLN), synchronously pumped by a 20-fs Ti:sapphire laser is reported. By using crystal interaction lengths as short as 250 μm, 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 (4589-2680 cm-1) by cavity delay tuning, providing up to 33 mW of output power at 3723 nm. The idler spectra exhibit stable broadband profiles with bandwidths spanning over 422 nm (FWHM) recorded at 3732 nm. The effect of crystal length on spectral bandwidth and pulse duration is investigated at a fixed wavelength, confirming near-transformlimited 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., Peer Reviewed, Postprint (published version)

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.

A continuous-wave singly-resonant optical parametric oscillator (SRO) with an optimum extraction efficiency, that can be adjusted independent of the pump power, is demonstrated. The scheme employs a variable-reflectivity volume Bragg grating (VBG) as the output coupler of a ring cavity, omitting any additional intra-cavity elements. In this configuration, we obtained a 75%-efficient SRO with a combined signal (19 W @ 1.55 mu m) and idler (11 W @ 3.4 mu m) output power of 30 W., QC 20141203

For the first time, fiber Raman lasers produced near-infrared wavelengths from directly diode-pumped by high-power multimode diode sources and on a fiber OPO at red wavelengths. The fiber Raman laser reached 20 W of output power at 1019 nm, pulsed operation at 835 nm, and M square = 2 at 1019 nm from a double-clad fiber Raman laser. These three results are all world records or world firsts. It was also found that the fiber OPO suffers from below-par gain at the anti-stoles wavelength of 718 nm. An OTDR is constructed to see how the 718 nm power evolves in the gain fiber. This is likely the first time this has been done. We find that the power grows exponentially for the first part of the fiber. After that, the growth is much slower. Even in the high-growth part, the gain is only 10% of what theory predicts. The reason for this is unclear, but we suspect it is caused by fiber longitudinal fiber variations, which modify the dispersion and therefore disrupt the phase-matching. Attempts to control the dispersion by heating a section of the fiber showed that the conversion did change, but for the worse rather than for the better in these preliminary attempts., The original document contains color images.

We demonstrate longwave infrared (LWIR) generation with an optical parametric oscillator (OPO) based on quasi-phasematched orientation-patterned gallium arsenide (OPGaAs). The OPGaAs OPO was directly pumped with a Q-switched lambda=2.054 micron Tm,Ho:YLF laser. OPGaAs samples representing three different grating periods were used to explore the LWIR OPO performance yielding outputs ranging from lambda=2.5-2.7 micron (signal) and lambda=8.8-11.5 micron (idler). Slope efficiencies for the combined signal and idler outputs reach as high as 26% while slope efficiencies for only the idler reached 8%. Spectral measurements of OPO output confirm good agreement with theoretical calculations., Prepared in collaboration with the University of Dayton, OH.

Presented at the AFOSR Spring Review 2013, 4-8 March, Arlington, VA.

[ANGLÈS] In this project we present a new technique to stabilize the cavity length of a tunable synchronously-pumped OPO and consequently achieve wavelength stability using more standard equipment commonly used to stabilize single frequency lasers. This technique is based on a concept that was introduced years ago in the context of mode-locked lasers [1], in which a conventional interferometer is synchronized to the repetition rate (RR) of the laser. In this work, we will implement the use of this technique to ultrafast OPOs by deploying an external Fabry-Perot interferometer synchronous with high harmonic number (about14th) of the OPO?s RR. In order to stabilize our OPO to this reference cavity, we use standard feedback techniques where the Fabry-Perot is modulated and the signal from the detector is demodulated by a lock-in amplifier, thus providing our error signal. This one is in turn integrated by our stabilizer, before being sent to the OPO piezoelectric driver. We will present characterization of the wavelength stability and fine tuning of the signal output pulse train for both long and short term regimes., [CASTELLÀ] En este proyecto se presenta una nueva técnica para estabilizar la longitud de la cavidad de un sintonizable OPO sincrónica de bombeo y en consecuencia lograr la estabilidad banda de frecuencia con más equipamiento estándar utilizada para estabilizar los láseres de frecuencia única. Esta técnica se basa en un concepto que se introdujo hace años en el contexto de modo bloqueado láseres [1], en el que un interferómetro convencional se sincroniza con la tasa de repetición (RR) del láser. En este trabajo, vamos a implementar el uso de esta técnica para ultrarrápida OPO mediante la implementación de un interferómetro Fabry-Perot externo sincronizado con alto número armónico (about14th) del RR del OPO. Con el fin de estabilizar nuestra OPO a esta cavidad referencia, usamos técnicas de realimentación estándar donde el Fabry-Perot es modulada y la señal del detector es demodulada por un amplificador lock-in, proporcionando así nuestra señal de error. Éste es a su vez integrado por nuestra estabilizador, antes de ser enviado al conductor piezoeléctrico OPO. Vamos a presentar la caracterización de la estabilidad de la longitud de onda y la puesta a punto de la salida del tren de pulso de la señal de los regímenes a largo y corto plazo., [CATALÀ] En aquest projecte es presenta una nova tècnica per estabilitzar la longitud de la cavitat d'un sintonitzable OPO sincrònica de bombament i en conseqüència aconseguir l'estabilitat banda de freqüència amb més equipament estàndard utilitzada per estabilitzar els làsers de freqüència única. Aquesta tècnica es basa en un concepte que es va introduir fa anys en el context de manera bloquejat làsers [1], en el qual un interferòmetre convencional se sincronitza amb la taxa de repetició (RR) del làser. En aquest treball, anem a implementar l'ús d'aquesta tècnica per ultraràpida OPO mitjançant la implementació d'un interferòmetre Fabry-Perot extern sincronitzat amb alt nombre harmònic (about14th) de l'RR del OPO. Per tal d'estabilitzar la nostra OPO a aquesta cavitat referència, fem servir tècniques de realimentació estàndard on el Fabry-Perot és modulada i el senyal del detector és demodulada per un amplificador lock-in, proporcionant així la nostra senyal d'error. Aquest és al seu torn integrat per la nostra estabilitzador, abans de ser enviat al conductor piezoelèctric OPO. Anem a presentar la caracterització de l'estabilitat de la longitud d'ona i la posada a punt de la sortida del tren de pols del senyal dels règims a llarg i curt termini.

[ANGLÈS] In this project we present a new technique to stabilize the cavity length of a tunable synchronously-pumped OPO and consequently achieve wavelength stability using more standard equipment commonly used to stabilize single frequency lasers. This technique is based on a concept that was introduced years ago in the context of mode-locked lasers [1], in which a conventional interferometer is synchronized to the repetition rate (RR) of the laser. In this work, we will implement the use of this technique to ultrafast OPOs by deploying an external Fabry-Perot interferometer synchronous with high harmonic number (about14th) of the OPO?s RR. In order to stabilize our OPO to this reference cavity, we use standard feedback techniques where the Fabry-Perot is modulated and the signal from the detector is demodulated by a lock-in amplifier, thus providing our error signal. This one is in turn integrated by our stabilizer, before being sent to the OPO piezoelectric driver. We will present characterization of the wavelength stability and fine tuning of the signal output pulse train for both long and short term regimes., [CASTELLÀ] En este proyecto se presenta una nueva técnica para estabilizar la longitud de la cavidad de un sintonizable OPO sincrónica de bombeo y en consecuencia lograr la estabilidad banda de frecuencia con más equipamiento estándar utilizada para estabilizar los láseres de frecuencia única. Esta técnica se basa en un concepto que se introdujo hace años en el contexto de modo bloqueado láseres [1], en el que un interferómetro convencional se sincroniza con la tasa de repetición (RR) del láser. En este trabajo, vamos a implementar el uso de esta técnica para ultrarrápida OPO mediante la implementación de un interferómetro Fabry-Perot externo sincronizado con alto número armónico (about14th) del RR del OPO. Con el fin de estabilizar nuestra OPO a esta cavidad referencia, usamos técnicas de realimentación estándar donde el Fabry-Perot es modulada y la señal del detector es demodulada por un amplificador lock-in, proporcionando así nuestra señal de error. Éste es a su vez integrado por nuestra estabilizador, antes de ser enviado al conductor piezoeléctrico OPO. Vamos a presentar la caracterización de la estabilidad de la longitud de onda y la puesta a punto de la salida del tren de pulso de la señal de los regímenes a largo y corto plazo., [CATALÀ] En aquest projecte es presenta una nova tècnica per estabilitzar la longitud de la cavitat d'un sintonitzable OPO sincrònica de bombament i en conseqüència aconseguir l'estabilitat banda de freqüència amb més equipament estàndard utilitzada per estabilitzar els làsers de freqüència única. Aquesta tècnica es basa en un concepte que es va introduir fa anys en el context de manera bloquejat làsers [1], en el qual un interferòmetre convencional se sincronitza amb la taxa de repetició (RR) del làser. En aquest treball, anem a implementar l'ús d'aquesta tècnica per ultraràpida OPO mitjançant la implementació d'un interferòmetre Fabry-Perot extern sincronitzat amb alt nombre harmònic (about14th) de l'RR del OPO. Per tal d'estabilitzar la nostra OPO a aquesta cavitat referència, fem servir tècniques de realimentació estàndard on el Fabry-Perot és modulada i el senyal del detector és demodulada per un amplificador lock-in, proporcionant així la nostra senyal d'error. Aquest és al seu torn integrat per la nostra estabilitzador, abans de ser enviat al conductor piezoelèctric OPO. Anem a presentar la caracterització de l'estabilitat de la longitud d'ona i la posada a punt de la sortida del tren de pols del senyal dels règims a llarg i curt termini.

We employed a 9-mm long periodically-poled KTiOPO 4 (PPKTP) crystal with a domain inversion period of 37.8 ÎŒm in an optical parametric oscillator (OPO) to generate sub-nanosecond pulses around 2.8 ÎŒm. With a 1-cm long OPO cavity in a singly resonant configuration with double pass pumping the OPO threshold was 110 ÎŒJ at 1064 nm (1-ns pump pulses at 1064 nm). The maximum idler output energy reached 110 ÎŒJ (quantum conversion efficiency of 32.5%). The signal pulse duration (FWHM) was 0.72 ns and the estimated idler pulse duration was 0.76 ns. At room temperature the signal and idler wavelengths were at 1722 and 2786 nm., QC 20120629

We investigate the effects of deterministic and stochastic phase modulation in the pump on the spectra and the generation efficiency of the counterpropagating parametric waves in a mirrorless optical parametric oscillator., QC 20220627Part of proceedings: ISBN 978-155752943-5Not duplicate with DiVA 587277

Premi extraordinari doctorat curs 2011-2012, àmbit de Ciències, High-power, continuous-wave (cw), mid-infrared (mid-IR) laser sources are of interest for variety of applications such as trace gas detection and remote sensing, which require broad spectral coverage to address the most prominent absorption features of a wide range of molecular species particularly in the mid-IR fingerprint region. On the other hand, surgical applications require high energy sources with unique pulse structure at specific wavelength in the mid-IR ranging from 6-6.5 m. Optical parametric oscillators (OPOs) offer potential sources for all the above applications. The output wavelengths of a singly-resonant oscillator (SRO) can be coarsely tuned over wide ranges through the adjustment of the nonlinear crystal temperature, phase-matching angle or, in the case of quasi-phase-matched (QPM) the first time. The high-energy CSP OPO marked the first demonstration of a compact, high-repetition-rate OPO synchronously pumped by a master oscillator power amplifier system at 1064 nm, generating an milli-joule pulses in the 6-6.5 m spectral range, which is technologically important for surgical applications. Additionally, we also demonstrated a fiber-based-green source at 532 nm, based on single-pass second harmonic generation (SHG) in MgO:sPPLT, as an alternative pump source for Ti:sapphire laser, pointing towards the future, compact fiber-laser pumped Ti:sapphire lasers. Further efforts to improve the SHG efficiency led to the development of a novel multi-crystal scheme, enabling single-pass SHG efficiency as high as 56%. This generic technique is simple and can be implemented at any wavelength. materials, the QPM grating period. The combination of SRO with a tunable pump laser allows the development of uniquely flexible and rapidly tunable class of mid-IR sources. In this thesis we have demonstrated several mid-IR OPOs in the cw as well as ultrafast picosecond regime pumped by fiber-lasers making them compact and robust. In the cw regime, we developed a high-powe, Fuentes coherentes de luz continua y de alta potencia en el infrarrojo-medio (mid-IR) son de gran interés por su aplicación en la detección de gases, detección remota y la observación de imágenes. Estas aplicaciones requieren un ancho de banda amplio para evidenciar las características que ofrece la absorción de una gran variedad de especies moleculares, particularmente en la región “finger print” del mid-IR. Por otra parte, fuentes altamente energéticas con pulsos que posean estructuras peculiares en rangos específicos de longitud de onda en el mid-IR, entre 6-6.5 m. , prometen características únicas para nuevas aplicaciones en cirugía. Osciladores ópticos paramétricos (OPOs) constituyen fuentes de luz versátiles y apropiadas para todas las aplicaciones mencionadas anteriormente. La longitud de En el régimen ultrarápido, hemos demostrado una nueva técnica de interferometría para la optimización absoluta de la potencia de salida de un oscilador óptico con una cavidad de anillo. Como demostración de principio, implementamos, por primera vez, un OPO de picosegundos en el mid-IR basado en MgO:PPLN con una cavidad de anillo bombeado por un láser de fibra de Yb. Además, hemos desarrollado un nuevo OPO de alta energía en el mid-IR basado en el material nolineal CSP. Esto representa la primera demostración de un OPO compacto de alta repetición sincrónicamente bombeado por un láser de estado sólido a 1064 nm generando pulsos de milijulios en el rango espectral 6-6.5 m. Esta radiación es importante para aplicaciones en cirugía. Adicionalmente, hemos demostrado una fuente verde, 532 nm, basada en láseres de fibra. Esta radiación se obtiene por medio de la generación de segundo harmónico (SHG) en un paso individual en MgO:sPPLT. Esto representa una nueva alternativa de bombeo para los láseres de Ti:sapphire que los harán compactos en el futuro. Los esfuerzos para mejorar la eficiencia de segundo harmónico resultaron en el desarrollo de un novedoso esquema que utiliza múltiples, Award-winning, Postprint (published version)

[ANGLÈS] We demonstrate a stabilized phase-locked divide-by-2 synchronously pumped optical parametric oscillator (SPOPO) based on BiB3O6 (BIBO) a crystal with type I interaction in the xz plane operating in degenerate regime. The femtosecond SPOPO is pumped by a KLM Ti:sapphire and uses a 1.5 mm long BIBO crystals cut for collinear type I (e ? o + o) PM in the xz optical plane at an internal angle ? = 11.4º (? = 0º) at normal incidence. The phase-locking operation was confirmed by splitting at the beginning the pump into two experimental lines (divided-by-2) overlapping them at the end of the experimental line setting a Mach-Zehnder interferometer. The SPOPO signal and idler output (1.5 ?m and 1.6 ?m aprox. respectively) was frequency doubled (SHG) and after was overlapped with the pump. The observation of stationary fringes from the interference established phase coherence. Additionally, we report the generation of a toothed shape in the spectrum of the overlapped signal and idler pulses of the SPOPO across 1.5-1.6 ?m and 1.6-1.7 ?m respectively in the degeneracy regime which can suggest the fact that an optical comb might have been generated., [CASTELLÀ] Se demuestra la estabilidad de un oscilador óptico paramétrico con bombeo sincronizado (SPOPO) dividido en dos funcionando en modo phase-locked. Éste se basa en un cristal BiB3O6 (BIBO) con interacción de tipo I operando en el plano óptico xz en régimen degenerado. El SPOPO, que funciona en femtosegundos, está bombeado por un láser Titanio-Zafiro funcionando en modo KLM y usa un cristal BIBO de 1.5 mm de longitud cortado para un phase-matching (ajuste de fases) colinear de tipo I (e ? o + o) en el plano óptico xz con un ángulo interno de incidencia de ? = 11.4º (? = 0º) respecto a la normal. El efecto de phase-locking fue confirmado dividiendo en dos líneas experimentales el haz de bombeo inicial superponiéndolas posteriormente configurándose como un interferómetro de Mach-Zehnder. A los haces de salida del SPOPO: el señal y el retrasado (1.5 ?m y 1.6 ?m respectivamente) se les dobló la frecuencia (SHG) antes de hacerlo interferir con el haz de bombeo de la otra línea experimental. La observación de franjas de interferencia estacionarias demuestra que existe coherencia en ambos haces de las líneas del experimento. Además, se reporta la generación de un perfil dentado en el espectro debido a la superposición de los pulsos señal y retrasado del SPOPO en régimen degenerado, lo que sugiere que podríamos haber generado un peine óptico., [CATALÀ] Es demostra l'estabilitat d'un oscil·lador paramètric polsat amb bombeig sincronitzat (SPOPO) dividit en dos feixos funcionant en mode phase-locked. L'oscil·lador està basat en un cristall de BiB3O6 (BIBO) en configuració tipus I operant en el pla òptic xz en règim degenerat. El SPOPO, que treballa en el règim de femtosegons, està bombejat mitjançant un làser de titani-safir funcionant en mode KLM i fa servir un cristall BIBO de 1.5 mm de longitud tallat per tal d'aconseguir un phase-matching colineal de tipus I (e ? o + o) en el pla xz amb un angle intern de ? = 11.4º (? = 0º) respecte la normal. L'efecte del phase-locking és confirmat dividint el feix de bombeig inicial en dos i posteriorment superposant-los en una configuració d'interferòmetre de Mach-Zender. Els feixos de sortida de l'SPOPO: el senyal i el retardat (1.5 ?m i 1.6 ?m respectivament) són doblats en freqüència (SHG) abans de fer-los interferir amb el feix de bombeig de l'altra línia experimental. L'observació de franges d'interferència estacionàries demostra que existeix coherència en ambdós feixos. A més a més, es demostra la generació d'un perfil dentat en l'espectre degut a la superposició dels polsos senyal i retardat de l'SPOPO en règim degenerat, fet que suggereix la creació d'una pinta òptica.

The final goal of the research project is the theoretical design of new optical devices on a Lithium Niobate and Tantalate platform; in particular we will focus on low-cost integrated optical pulse shapers on periodically poled Lithium Niobate and Tantalate waveguides. Our approach will be mainly used to design pulse shapers, but it also might open new design perspectives for other optical devices. In fact the continuous progress in the control of linear and nonlinear properties of optical waveguides has led nowadays to the possibility of engineering the design of integrated photonic components down to the sub micrometer space scale. Such waveguides exhibit a spatially periodic micro or nano-structure which enables the engineering of their dispersive and nonlinear properties to a degree that was previously unconceivable. This key technology has opened up new possibilities in diverse applications; in particular, from the system point of view, this entails that we can now imagine devices with performances that were totally unconceivable only a few years ago. As research continues to advance in this area new frontiers are explored: currently there is intense activity directed, on the one hand, to achieve even higher precision in the control of the linear and nonlinear properties of optical devices, and on the other hand to conceive new device functionalities, thanks to the increased number of degrees of freedom of the fabrication parameters. The latter issue might also open a new design perspective: up to now optical devices have been mainly designed on a try and test procedure that was reasonable since only a small number of parameters was free for the design (i.e. controllable in the fabrication process)., The original document contains color images.

This paper provides an overview of our work on nonlinear optical devices in MgO-doped nearly stoichiometric LiTaO3. We present experimental results for optical parametric oscillation and broadband generation obtained with one- and two- dimensional periodically poled structures., QC 20111201. QC 20160314