Search

International audience; Recently, we proposed an active mid-infrared (MIR) hyperspectral imaging system for early detection of plant water stress. A quantum cascade tunable laser powered this stand-off detection system, in which "speckle" in images due to coherent nature of laser radiation. The speckle affects the spatial resolution of the images. In this article, we evaluate several speckle suppression methods suitable for the mid-infrared region. To quantify the reduction of speckle, we compare their spatial contrast. We combined optical techniques and showed their ability to reduce the speckle contrast from its initial value 0.41s down to 0.11, representing a 73% reduction.

We demonstrate a compact and low-cost all-fiber-based locking setup for frequency-noise suppression of a 420 nm external-cavity diode laser. Frequency noise reduction in the 100 Hz to 800 kHz range is demonstrated up to 40 dB associated with a linewidth narrowing from 850 kHz to 20 kHz for 10 ms integration time. This simple locking scheme might be implemented for a large range of wavelengths and can be integrated on a small footprint for embedded applications requiring narrow linewidth blue laser diodes.

Narrow linewidth laser diodes (LDs) emitting in the near-UV (NUV) are gaining attention for applications ranging from spectroscopy to atom cooling and interferometry or other applications requiring high spectral purity. InGaN edge-emitting LDs can exhibit a power of hundreds of mW in an unstable multimode regime detrimental to aforementioned uses. In this paper we report on a compact and robust design based on a low-cost blue LD, a beam shaping optical system and a fiber Bragg grating (FBG) acting as a wavelength selective reflector. One longitudinal mode of the non-antireflection coated laser diode is selected by a close to 30 pm bandwidth FBG allowing a few mW output power around 400 nm and a sidemode- suppression-ratio approaching 50 dB exceeding our last published results. Our previous studies showed that a single-frequency regime with a sub-MHz integrated linewidth and an estimated intrinsic linewidth of 16 kHz was possible by a carefully engineered external cavity. We will study the influence of the cavity length with different fiber types (SM or PM). Assessment will focus on the linewidth and a detailed intensity and frequency noise analysis of the emission. We will also investigate for the first-time the stability of several types of UV-FBG submitted to tens of mW of 400 nm light guided into the fiber core. This work demonstrates state-of-the-art performances by connecting low-cost components and opens the way to the fabrication of highly coherent laser sources that could meet the markets for the NUV applications.

We realize a fiber Bragg grating InGaN-based laser diode emitting at 400 nm and demonstrate its high coherency. Thanks to the fabrication of a narrowband fiber Bragg grating in the near-UV, we can reach single-mode and single-frequency regimes for the self-injection locked diode. The device exhibits 44 dB side-mode suppression ratio and mW output power. Detailed frequency noise analysis reveals sub-MHz integrated linewidth and 16 kHz intrinsic linewidth. Such a narrow linewidth laser diode in the near-UV domain with a compact and low-cost design could find applications whenever coherency and interferometric resolutions are needed.

International audience; Plant water stress has been extensively studied using hyperspectral visible-and nearinfrared systems. Thermal imaging and the recent availability of widely tunable infrared quantum cascade laser (QCL) allow us to propose an active hyperspectral imaging system operating in the mid-infrared (MIR) band, where the system output consists of a series of narrowband subimages arranged across the reflectance spectrum of the sample, forming a hypercube data acquired by "staring" acquisition technique. To evaluate more precisely the capabilities of the active hyperspectral imaging, we propose a system composed of four powerful tunable QCL covering the 3.9-to 4.7-μm and 7.5-to 11-μm wavelengths ranges. Two cameras are used for detection: an InSb cooled camera ranging from 3 to 5 μm and a bolometer from 7.5 to 13 μm range. This system is validated by applying to growing plants for early water stress detection. Finally, we present and discuss results using partial least squares discriminant analysis classification technique to characterize water status of different plants, separated in two classes: control subjects were maintained at 80% of the amount of water to soil saturation ratio and stressed subjects at 20%. Initial discrimination results have shown the efficiency of the proposed system.

International audience; Thermal imaging and the recent availability of widely tunable infrared QCL lasers (Quantum Cascade Laser) allow us to propose an active hyperspectral imaging system operating in mid-infrared (MIR) band to obtain simultaneously large amounts of spatial and spectral information on the samples. In order to evaluate more precisely the capacities of the active hyperspectral imaging, we propose a system composed of four powerful QCL tunable lasers (in order to cover 3-5 μm and 7-11 μm wavelengths) and three cameras: a visible and near-infrared (NIR) range, a bolometer for 7-13 μm range and an InSb cooled camera for 3-5 μm range. We present the algorithm for image acquisition, image and data processing. Finally, we present and discuss some preliminary results using this system to characterize plant leaves under controlled growing conditions.

International audience; The first InGaN-based LDs were reported in 1996 by Nakamura and co-workers [1] and commercialized from 1999 by the Nichia Corporation. Since then, huge efforts have been devoted to the optimization of the epitaxial layers (doping, defect concentration, shortening of the radiative lifetime, etc.). Nowadays, blue laser diodes emitting hundreds of mW are commercially available but they often exhibit multimode behaviors for both transverse and longitudinal directions. The InGaN-based laser diode technology is still in its infancy, compared to its long wavelength counterparts and only recently the first electrically pumped single mode blue laser diodes have been demonstrated [2] with a resolution limited linewidth of 11.7 GHz. At telecom wavelengths, a mature approach to force the laser diode in a single frequency regime consists in using an external feedback by means of Fiber Bragg Grating [3,4]. Nevertheless, to our knowledge, such a compact design has not been proposed for blue laser diodes yet.

International audience; Nowadays, narrow linewidth lasers are unavoidable tools for fundamental and applied physics. One promising approach to generate coherent laser emission is based on stimulated Brillouin scattering (SBS) optical nonlinearity. Implementing SBS in an optical cavity gives rise to coherent emission with impressive performances in terms of noise and linewidth. Cascading the SBS process can even, under given conditions, improves the coherent emission specifications. To achieve such performances it is crucial to determine the Brillouin gain coefficient. Usual pump-probe methods are carried out in single pass waveguides. The probe intensity is proportional to e gBP in L eff / A eff where P in is the incident pump power, A eff the effective mode area and L eff the usual effective interaction length. To observe significant probe amplification one needs either long waveguides or strong pump power to reach the SBS threshold. We propose a method, based on the cavity ringdown spectroscopy, to directly characterize the Brillouin gain coefficient inside a resonator. This configuration allows to extract Brillouin parameters from the light recirculation with both a reduced waveguide length and input pump power when compared to usual methods.

International audience; We report a technique based upon the cavity ringdown method that enables to characterize the Brillouin gain coefficient directly in a laser cavity. Material gain, optical cavity parameters and lasing properties can be extracted from measurements whithin a single experiment.

International audience; We provide numerical verification of a feed-forward, heterodyne-based phase noise reduction scheme using single-sideband modulation that obviates the need for optical filtering at the output. The main benefit of a feed-forward heterodyne linewidth reduction scheme is the simultaneous reduction of the linewidth of all modes of a mode-locked laser (MLL) to that of a narrow-linewidth single-wavelength laser. At the heart of our simulator is an MLL model of reduced complexity. Importantly, the main issue being treated is the jitter of MLLs and we show how to create numerical waveforms that mimic the random-walk nature of timing jitter of pulses from MLLs. Thus, the model does not need to solve stochastic differential equations that describe the MLL dynamics, and the model calculates self-consistently the line-broadening of the modes of the MLL and shows good agreement with both the optical linewidth and jitter. The linewidth broadening of the MLL modes are calculated after the phase noise reduction scheme and we confirm that the phase noise contribution from the timing jitter still remains. Finally, we use the MLL model and phase noise reduction simulator within an optical communications system simulator and show that the phase noise reduction technique could enable MLLs as optical carriers for higher-order modulation formats, such as 16-state and 64-state quadrature amplitude modulation.

Brillouin fiber ring lasers (BFRLs) are based on the amplification of the Stokes signal wave generated by a pump signal seeded inside a fiber-ring cavity. Brillouin fiber ring lasers have already been extensively studied and results have shown that the generated first order Stokes wave has less intensity and phase noise than the seeded pump. This increase in coherence is attractive for many sensing applications, whether in the field of fiber sensors or remote sensing systems such as LIDAR. For input pump powers few times the 1rst order Stokes Brillouin lasing threshold, stimulated Brillouin scattering (SBS) in the fiber acts as a low-pass filter and reduces both frequency and intensity noise of the Stokes-1 signal relative to that of the pump. Brillouin fiber lasers with several Stokes components can further increase the coherence through a cascading effect, the 1st Stokes component being the pump for the 2nd Stokes order and so on. In this communication, we experimentally demonstrate up to 40 dB FN reduction of a non-resonant pumping BFRL compare to that of the pump and show that it can reach even higher values (50 dB). To our knowledge, this is the first demonstration of such experimental FN (so its linewidth) reduction using non-resonant BFRLs. Using resonant pumping, and multi-Stokes Brillouin fiber lasers, we show that the RIN reduction is exceptionally increased (20 dB) through the cascading effect due to the saturation process of the Stokes signal used as an optical pump. We stated that the multi-Stokes operation is mandatory to obtain high RIN-Reduction, while the frequency noise reduction is maintained at a high level (30 dB). Analytical expressions obtained for the noise power density enables us to predict this reduction showing the effect of the cavity (Q-factor) and of acoustic damping rate. Chalcogenide and silica fibers are compared.

International audience; We demonstrate that multi-Stokes operation is essential to get low intensity noise Brillouin fiber ring laser. 20 dB/Hz noise reduction compared to input pump laser is confirmed by a numerical modal replicating experimental observation. Stimulated Brillouin Scattering (SBS) initiated in an optical cavity is an attractive phenomenon to generate narrow linewidth lasers. Multi-Stokes waves generated through cascade process allow to reach better coherence properties. We build a Brillouin multi-Stokes fiber laser with 20 meters Polarization Maintained fiber. This fiber ring cavity is resonantly pumped using a continuous wave laser. The circulating pump wave initiates Brillouin amplification in Stokes 1 (S1) wave traveling in the opposite direction. We show characteristics of cascade Brillouin laser on the Figure (left axis). S1 (blue), S2 (green), and S3 (yellow) output power are plotted as function of input pump power. When the power in S1 reaches the normalized output power needed to compensate linear losses of S2, coherent emission of S2 takes place; the cascaded process is on. In that regime, the S1 circulating power is clamped. Relative intensity noise (RIN) of individual Stokes are characterized and normalized by the pump RIN. RIN behavior of the three first individual Stokes lines as function of the input pump power are plotted on the Figure (right axis). Above, which corresponds to the S2 lasing threshold, the S1 experiences an abrupt RIN reduction up to 20 dB/Hz compared to the input pump RIN level. This reduction originates from the clamping effect of S1 line due to the appearance of the stimulated S2 emission. Dotted lines correspond to measured RIN and starred lines to numerical simulations based on a set of coupled-mode equations. Numerical results even predict 40 dB/Hz reduction. We assume that the discrepancy is due to experimental bench limitation. We finally show that Stokes RIN follows the noise distribution similar to a class B laser featuring relaxation of oscillations, originating from the coupling between phonons and photons. Our study gives inputs to design optimized Brillouin fiber laser in term of RIN reduction.

International audience; Brillouin gain coefficient is usually evaluated using well-established pump-probe technique. We report a technique based upon the cavity ringdown method that enables to characterize this fundamental parameter directly in a Brillouin laser cavity. Indeed, within a unique experimental setup, material gain, optical cavity parameters and laser properties can be extracted. This method would be particularly suitable for micro-resonator lasers intracavity material Brillouin gain determination.

International audience; We report on the frequency noise reduction performance of a feed-forward technique. The Letter is based on frequency noise measurements that allow the spectral response of the feed-forward phase noise correction to be determined. The main limitation to the noise compensation is attributed to the local oscillator flicker noise and the noise added by the optoelectronic loop elements. The technique is applied to an actively mode-locked laser diode demonstrating, at the output of the system, an optical frequency comb source with 14 comb lines reduced to sub-kilohertz intrinsic linewidth.

International audience; Summary form only given. Brillouin fiber ring lasers have already been extensively studied and results have shown that the generated first order Stokes wave has less intensity and phase noise than the seeded pump. This increase in coherence is attractive for many sensing applications, whether in the field of fiber sensors or remote sensing systems such as LIDAR. Brillouin fiber lasers with several Stokes components can further increase the coherence through a cascading effect, the 1st Stokes component being the pump for the 2nd Stokes order and so on. In this communication, we investigate the noise properties of a multi-Stokes Brillouin fiber laser. We present numerical simulations from a model that is an extension of the usual three-waves model of stimulated Brillouin scattering in agreement with experimental results.

International audience; Up to 16 dB frequency noise reduction and a linewidth 8 times narrower that of the pump source is reported for the Stokes component in a compact Brillouin fiber laser made of chalcogenide microstructured fiber. Since the pump wave is not resonant in the ring cavity, an active stabilization of the laser is not primordial thus making the system simpler and cheaper. Although only a 3 metre-long microstructured chalcogenide fiber was used as gain medium, a very low laser threshold power of 6 mW was obtained for nonresonant pumping. The linewidth-narrowing effect achieved in our BFL cavity is also discussed.

This paper reports on all optical frequency down conversion clock recovery based on Quantum-Dash Fabry-Perot mode-locked laser diode (QD-MLLD). A first section is dedicated to the generation of a tunable repetition rate pulse source based on a first QD-MLLD. The principle is to select three lines in the QD-MLLD spectrum with a filtering technique; the lines spacing are properly chosen to generate the desired repetition rate. In this paper, a frequency of 427 GHz was reached and observed with an optical sampling oscilloscope. Moreover, an encoded 170.8 GHz pulse source was characterized showing no penalty in comparison with our reference obtained by Optical Time Division Multiplexing (OTDM), which confirms the quality of the optical clock. In a second section, we show a clock frequency down conversion based on a second QD-MLLD, which is optically injected by a pulse source, whose repetition rate is 10 times higher than its self pulsating frequency. The 42.7 GHz down converted clock is then encoded and analyzed showing no penalty in comparison to a standard 42.7 Gbit/s reference, demonstrating its quality. Finally, in a third section, we demonstrate sub-harmonic clock recovery with a QD-MLLD, when a data stream is injected. We measure a penalty of 0.3 dB when compared to a standard 42.7 Gbit/s reference.

International audience; The onset of the coherence collapse (CC) regime, which is incompatible with data transmission, is investigated both theoretically and experimentally in a 1.55-um InAs/InP quantum dash semiconductor laser. It is numerically shown that the filling from the excited state produces an additional term, which accelerates the route to chaos. This contribution can be seen as a perturbation that reduces the overall CC threshold.

Seeding light from a laser into the cavity of a second one is a simple experiment largely encountered in optical domain (Stover, H.L., Steier, W.H.: Appl. Phys. Lett. 8, 91–93 (1966); Lang, R.: IEEE J. Quant. Elect. 18(6), 976–983 (1982)). With an unidirectional coupling, optical injection is a basic tool to study synchronization process between oscillators. The dynamics induced in this experiment have been extensively described, theoretically and experimentally (Simpson, T.B. et al.: Quant. Semiclassical Opt. 9(5), 765–784 (1997); Wieczorek S.: Opt. Commun. 172, 279–295 (1999); Blin, S.: Comptes Rendus de la Phys. 4(6), 687–699 (2003)) but mainly when the seeded light is a continuous wave (CW). In this paper, we describe the synchronization on an undamped relaxation regime. In order to study the degree of correlation between the two synchronized lasers (TL and RL), we use a cascade of two optical injections (Guignard, C.: Conference on Lasers and Electro Optics—the Europeen Quant. Electronics Conference (CLEO-EQEC), Munich (Germany), EC1M (2003)) thus three lasers: Master-transmitter laser (TL)-receiver laser (RL). The seeding by a field showing undamped relaxations can be directly compared with the optical injection by a CW signal, especially when the injected power and the detuning between the TL and RL frequencies are varied. Synchronization on undamped relaxation are shown to occur at values of the optical injected power and detuning, for which the RL is in the locked or wave-mixing regime when it is seeded by a CW. However, additional tongues of synchronization also exist at detuning equal to the relaxation oscillation frequency (ROF).

International audience; An analysis of optical injection on a gain-switched distributed feedback (DFB) laser and its impact on pulse parameters that influence the performance of the pulse source in high-speed optical communication systems is presented in this paper. A range of 10 GHz in detuning and 5 dB in injected power has been experimentally identified to attain pulses, from an optically injected gain-switched DFB laser, with durations below 10 ps and pedestal suppression higher than 35 dB. These pulse features are associated with a side mode suppression ratio of about 30 dB and a timing jitter of less than 1 ps. This demonstrates the feasibility of using optical injection in conjunction with appropriate pulse compression schemes for developing an optimized and cost-efficient pulse source, based on a gain-switched DFB laser, for high-speed photonic systems.

International audience; We present here for the first time experimental bifurcation diagrams of a self-pulsing dual wavelength erbium-doped fiber laser. New type of generalized bistabilities are observed such as 3T-chaos and 1T-chaos. Theoretical calculation based on the two-mode ion-pair model shows a very good agreement with the experimental results.

International audience; Laser spectra are strongly modified by the optical feedback which is provided by external cavities; here we give a preliminary experimental result describing the optical spectrum of a fibre laser having two identical end cavities, which appear between the external mirrors and fibre ends. One observes a channelled spectrum including mode clusters separated by empty regions. We use the optical Airy function defined in the pure frequency domain to study these spectra. An optical Vernier effect allows the description of this structure. The linewidth of each mode is calculated as a function of the gain, by using the same Airy function.

We propose in this communication an experimental study of the relaxation oscillations behavior in mode-locked lasers. The semiconductor self-pulsating laser diode is composed by two gain sections, without saturable absorber. It is made of bulk structure and designed for optical telecommunication applications. This specific device allows two different regimes of optical modulation: the first one corresponds to the resonance of the relaxation oscillations and the second one, to the mode-locking regime at FSR value. This singular behavior leads us to characterize the self-pulsations which are coexisting in the laser and to describe two regimes of output modulation: the first one appears thanks to the resonance of the oscillation relaxation and the other one corresponds to the FSR of the Fabry-Perot laser at 40 GHz., poster session, SPIE Photonics Europe, Strasbourg : France (2008)

Dense wavelength division multiplexing (DWDM) metropolitan networks are currently being extensively deployed with distances ranging from a couple of ten’s kilometers to several hundred kilometers. 40 DWDM channels are commonly used; each of them is carrying today Ethernet or Fiber Channel traffics ranging from 1 to 10 Gb/s. This type of network requires achromatic components, for which the provider can fix the operating wavelength in order to have the same type of components in the consumer’s home. The DWDM sources could be based on a tunable laser source or on a selfseeded- reflective semiconductor optical amplifier (RSOA) as recently proposed. In this last case, the RSOA is coupled to a mirror, located at a few kilometers in a central office. A frequency filter fixes the wavelength. The RSOA is then directly modulated at a few GHz. However even if a 100 GHz-wide filter is used, a much narrower slot of wavelengths is selected on the “red” side of the transmission window of the filter. This communication gives from a Green function approach the modal structure of an RSOA coupled to a long cavity with strong optical feedback and explains how such coupled structure is operating.

An Er:ZBLAN microspherical laser has several laser lines around 1.55 μm with narrow bandwidths ( 50-100 kHz). Such a laser is used as a master laser to optically inject a slave DFB semiconductor laser. We show that the slave can be easily locked by one microsphere mode only, enabling a spectral narrowing of the laser line (from 30 MHz to 67 kHz). We stress the selective process of light amplification and filtering effect by the DFB slave.

We give an analysis of the spectrum around the laser line of vertical-cavity surface-emitting lasers. We show that they contain sidebands which are not symmetrically located on each side of the laser frequency and that this asymmetry corresponds to a non-degeneracy of relaxation oscillations of the carriers. A model which explains this non-degeneracy is introduced.

The amplification response of a laser to a weak, narrow line width signal is measured above the laser threshold and below the minimum injection power condition for locking. This signal has the same resonant frequency as the laser but a smaller line width which allows to separate its effect from that of the spontaneous emission in the laser output spectral density. Optical powers as low as −117 dBm or 0.2 photon per correlation time are experimentally detected. Phenomena are theoretically explained by using simple semiclassical formulas based on the laser transfer function.

The process of amplification of light by a laser set above its oscillation threshold is studied. This laser has a wide bandwidth (typically 100 MHz) and is injected by a signal whose bandwidth is much narrower, which allows to separate the amplified signal from the ordinary laser spectral density. Theoretical calculations are based on simple semiclassical formulas and agree with the experimental results which are performed at 1.55 μm using single-mode semiconductor lasers. The amplification arises from a progressive channeling of energy from the wider laser line onto the narrow injected signal.

Nous montrons que la fonction de transfert generalisee au laser introduite recemment [1] nous permet de decrire l'evolution de la largeur de raie d'un laser libre ou optiquement injecte.

This work addresses the linewidth properties of a distributed-feedback semiconductor laser submitted to optical injection. Experimentally, we first verify that under frequency-locking conditions, the slave laser has the same linewidth as the master. It can be smaller or larger than that of the free-slave laser. For lasers tuned on the same central frequency when the injected power decreases or when the master linewidth increases, we observe a partial linewidth transfer (progressive phase locking). These effects are well described theoretically by the Airy function generalized to the laser.

We study a vertical-cavity surface-emitting laser with external feedback through a quarter-wavelength plate. We show that the effect of a rotation of the quarter-wavelength plate is to shift one comb of modes with respect to the other one. The dependence of the frequency on the rotation angle is calculated and shown to be in good agreement with experimental results.

The polarization state of a vertical cavity surface emitting laser (VCSEL) output was driven by means of optical injection from another VCSEL. The bistability inherent to polarization locking allowed us to generate a memory effect. The control parameter was the modulated bias current of the maser laser and effects were shown to exist at frequencies up to 1 GHz.

An injected microchip laser is theoretically studied, with the use of two models: in the first model, which is traditional, the field is represented by a single frequency component in the slowly-varying envelope approximation. In the second model, referred to as the Fabry-Perot model, two field components are considered which are respectively centered around the frequency of an eigenmode of the injected laser and the frequency of the injected field. Computation of locking ranges, bistability do mains are performed and the results compared. They show not only an improved precision of the second model but also a necessity to use it to describe some effects such as the bistable domains in the limits of the locking domains.

We study experimentally and theoretically two polarization effects in a vertical cavity surface emitting laser submitted to optical feedback. In a first experiment, we obtain flips between two linearly polarized laser modes up to a frequency of 50 MHz using an external cavity with a polarizer. In a second experiment, polarization self modulation is demonstrated up to a frequency of 2.6 GHz, using a quarter wave plate instead. Numerical calculations, based on a four levels model for the active medium, show a good agreement with the experiments.

Vertical-cavity surface-emitting lasers (VCSELs) are known to exhibit a small birefringence and dichroism whose axes are directed along the crystal axes of the quantum wells and which fix the polarization of the oscillating light. In this paper, we consider the dynamics of the polarization of light in such a laser, extended by means of a quarter-wavelength plate in an external cavity. Periodic variations are experimentally observed. A theoretical analysis and numerical results are proposed, using a recent model which includes the carriers' spin interaction. A good match is found between experimental and numerical results.

For underwater surveillance applications, an all-optical acoustic array technology allows enhanced capabilities compared to conventional piezoelectric antenna in terms of compactness, robustness and large distance remote interrogation through small diameter optical cable. This paper presents the results obtained on a first full optical antenna panel based on an innovative wideband pressure and temperature compensated fiber laser hydrophone. The presented mock-up includes 12 fiber-laser optical hydrophones interrogated through a 4 km lead optical cable.

A simple adjustment of the "Lang and Kobayashi" delayed rate-equations which describe the dynamics of an external-cavity semiconductor laser is shown to predict low-frequency resonances in the output intensity spectrum of the system. Numerical simulations with control parameter values-driving current and feedback strength-corresponding to our experiments show excellent agreement with theory. A possible mechanism for the occurrence of low-frequency self-oscillations is also proposed. >

A theoretical modeling of dual wavelength operation of erbium-doped fibre lasers is presented. The model is a generalization of the one used in the single mode theory, based on the existence of isolated ions and ion pairs coupled via the laser field. Analytical results are obtained in the steady state. The linear stability analysis of the coupled equations shows the existence of two pairs of complex conjugate eigenvalues and two real negative eigenvalues. These results imply that the system is driving by two frequencies : one associated with the classical relaxation oscillation and a low frequency characteristic of a bimodal system. When the ion pair concentration is increased, the real part of one pair of conjugate eigenvalues becomes positive. In such a situation, self-pulsing and chaotic dynamics occur together with antiphase effects between two mode intensities. Locking of the low frequency on a subharmonic of the high frequency is also obtained leading to nT-periodic orbits.

A compact second-order Stokes Brillouin fiber laser made of microstructured chalcogenide fiber is reported for the first time. This laser required very low pump power for Stokes conversion: 6 mW for first order lasing and only 30 mW for second order lasing with nonresonant pumping. We also show linewidth-narrowing as well as intensity noise reduction for both the 1st and 2nd order Stokes component when compared to that of the pump source.

International audience; We report for the first time a multiplexed array of 12 distributed feedback fiber lasers (DFB FLs) on a single optical fiber, separated by only 100 GHz (0.8 nm) in the C-band. These lasers are pumped by a 200 mW laser diode at 1480 nm with no apparent impact on the sensor noise floor despite the fact that the residual reflections from adjacent gratings may be enhanced due to the smaller wavelength separation. Each DFB FL, especially developed for serial multiplexing, exhibits low lasing threshold typically between 1 and 2 mW, low intensity noise and very low frequency noise (less than 30 dB re 1 Hz²/Hz at 1 kHz from optical carrier). From these experimental results, extension to 32 DFB FLs array (on 100 GHz ITU grid) multiplexed on one fiber will be discussed.

In this paper, an all-“ber Brillouin laser ring cavity using a 3-m-long suspended-core chalcogenide As 38 Se 62 “beris reported for the “rst time to our knowledge. For a nonresonant ring cavity with no servo-locking, a laserthreshold power of 37 mW and an eciency of 26 % were obtained for a “ber having a core diameter of 5 µ m.The linewidth of the Brillouin “ber laser and the pump laser were respectively measured to be below 4 kHz,the resolution of our autocorrelator, and 250 kHz, thus showing the linewidth-narrowing nature of the Brillouinlaser. This result paves the way to compact Brillouin lasers with low threshold power and good spectral purity.A full experimental Brillouin characterization is also reported. We measured a Brillouin gain spectrum of 14.2MHz, a Brillouin gain coecient of 5.6 × 10 Š 9 m/W and a Brillouin frequency shift of 7.95 GHz in our “ber.Keywords: Stimulated Brillouin scattering; chalcogenide “ber; Brillouin gain coecient; Brillouin gain spec-trum; suspended-core “ber; Brillouin “ber laser.

International audience; Relative intensity noise and frequency noise have been measured for the first time for a single-frequency Brillouin chalcogenide As38Se62 fiber laser. This is also the first demonstration of a compact suspended-core fiber Brillouin laser, which exhibits a low threshold power of 22 mW and a slope efficiency of 26% for nonresonant pumping.

International audience; Perfos and the laboratory Glasses and Ceramics Group of University of Rennes 1 have worked together to develop a new fabrication technique for chalcogenide preforms based on the glass-casting process. Various fiber profiles have been designed by the Fresnel Institute and fiber losses have been significantly improved, approaching those of the material losses. Using this technology, we have manufactured an AsSe CPCF exhibiting a nonlinear coefficient γ of 46 000 W-1km-1. Self-phase modulation, Raman effect, Brillouin effect, Four-Wave Mixing have been observed leading to the demonstration of various optical functions such four-wave mixing based wavelength conversion at 1.55 μm by FOTON, the demonstration of Raman Shifts and the generation of a mid-IR supercontinuum source by ONERA and the demonstration of a Brillouin fiber laser by FOTON.

International audience; A compact second-order Stokes Brillouin fiber laser made of microstructured chalcogenide glass is reported for the first time. This laser has very low optical pump-power threshold for Stokes conversion: 6 mW for first order and only 30 mW for second order with nonresonant pumping.