[Show abstract][Hide abstract] ABSTRACT: We demonstrate a nanosecond single-frequency nested cavity optical parametric oscillator (NesCOPO) based on orientation-patterned GaAs (OP-GaAs). Its low threshold energy of 10 μJ enables to pump it with a pulsed single-frequency Tm:YAP microlaser. Stable single-longitudinal-mode emission is obtained owing to Vernier spectral filtering provided by the dual-cavity doubly-resonant NesCOPO scheme. Crystal temperature tuning covers the 10.3-10.9 μm range with a quasi-phase-matching period of 72.6 μm. A first step toward the implementation of this device in a differential absorption lidar is demonstrated by carrying out short-range standoff detection of ammonia vapor around 10.4 μm. Owing to the single-frequency emission, interferences due to absorption by atmospheric water vapor can be discriminated from the analyte signal.
[Show abstract][Hide abstract] ABSTRACT: This work represents experimental demonstration of nonlinear diffraction in an orientation-patterned semiconducting material. By employing a new transverse geometry of interaction, three types of second-order nonlinear diffraction have been identified according to different configurations of quasi-phase matching conditions. Specifically, nonlinear Čerenkov diffraction is defined by the longitudinal quasi-phase matching condition, nonlinear Raman-Nath diffraction satisfies only the transverse quasi-phase matching condition, and nonlinear Bragg diffraction fulfils the full vectorial quasi-phase matching conditions. The study extends the concept of transverse nonlinear parametric interaction toward infrared frequency conversion in semiconductors. It also offers an effective nondestructive method to visualise and diagnose variations of second-order nonlinear coefficients inside semiconductors.
[Show abstract][Hide abstract] ABSTRACT: We investigate nonlinear diffraction in orientation-patterned semiconductors and identify Čerenkov second harmonic generation in a transverse geometry of interaction. Čerenkov second harmonic allows nondestructive 3D visualization of the internal structure of orientationpatterned semiconductor.
[Show abstract][Hide abstract] ABSTRACT: We report on a single-frequency nested cavity OPO based on OP-GaAs, pumped by a pulsed Tm:YAP microlaser. The threshold energy is 10 μJ and temperature tuning enables to cover the 10.3-10.9 μm range.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate a core-pumped Q-switched thulium-doped fiber laser system with fast tunability capability over 100 nm without any movable part. With up to 7 kW peak power in a diffraction-limited beam, this source is well adapted for pumping a frequency agile mid-IR parametric oscillator or amplifier based on Quasi-Phase-Match single-period crystals.
[Show abstract][Hide abstract] ABSTRACT: Laser ablation proved to be a reliable micro-fabrication technique for patterning and structuring of both thin film and bulk polymer materials. In most of the industrial applications ultra-violet (UV) laser sources are employed, however they have limitations such as maintenance costs and practical issues. As an alternative and promising approach, mid-infrared resonant laser ablation (RIA) has been introduced, in which the laser wavelength is tuned to one of the molecular vibrational transi-tions of the polymer to be ablated. Consequently, the technique is selective in respect of processing a diversity of polymers which usually have different infrared absorption bands. In this paper, we present mid-infrared resonant ablation of PolyMethyl MethAcrylate (PMMA), employing nanosec-ond laser pulses tunable between 3 and 4 microns. This RIA nanosecond laser set-up is based on a commercial laser at 1064 nm pumping a singly resonant Optical Parametric Oscillator (OPO) built around a Periodically-Poled Lithium Niobate (PPLN) crystal with several Quasi-Phase Matching (QPM) periods. RIA has been successfully demonstrated for structuring bulk PMMA, and selective patterning of PMMA thin films on a glass substrate has been implemented.
[Show abstract][Hide abstract] ABSTRACT: The fast growing market of organic electronics, including organic photovoltaics (OPV), stimulates the development of
versatile technologies for structuring thin-film materials. Ultraviolet lasers have proven their full potential for patterning
single organic layers, but in a multilayer organic device the obtained layer selectivity is limited as all organic layers show
high UV absorption. In this paper, we introduce mid-infrared (IR) resonant ablation as an alternative approach, in which
a short pulse mid-infrared laser can be wavelength tuned to one of the molecular vibrational transitions of the organic
material to be ablated. As a result, the technique is selective in respect of processing a diversity of organics, which
usually have different infrared absorption bands. Mid-IR resonant ablation is demonstrated for a variety of organic thin
films, employing both nanosecond (15 ns) and picosecond (250 ps) laser pulses tunable between 3 and 4 microns. The
nanosecond experimental set-up is based on a commercial laser at 1064 nm pumping a singly resonant Optical
Parametric Oscillator (OPO) built around a Periodically-Poled Lithium Niobate (PPLN) crystal with several Quasi-Phase
Matching (QPM) periods, delivering more than 0.3 W of mid-IR power, corresponding to 15 μJ pulses. The picosecond
laser set-up is based on Optical Parametric Amplification (OPA) in a similar crystal, allowing for a comparison between
both pulse length regimes.
The wavelength of the mid-infrared laser can be tuned to one of the molecular vibrational transitions of the organic
material to be ablated. For that reason, the IR absorption spectra of the organic materials used in a typical OPV device
were characterized in the wavelength region that can be reached by the laser setups. Focus was on OPV substrate
materials, transparent conductive materials, hole transport materials, and absorber materials. The process has been
successfully demonstrated for selective thin film patterning, and the influence of the various laser parameters is
[Show abstract][Hide abstract] ABSTRACT: We demonstrate a Q-switched thulium-doped fiber laser up to 20 kHz with fast tunability over 100 nm without any movable part. Emitted pulses have energies above 10 μJ and peak powers up to 400 W.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate a robust and simple method for measurement, stabilization and
tuning of the frequency of cw mid-infrared (MIR) lasers, in particular of
quantum cascade lasers. The proof of principle is performed with a quantum
cascade laser at 5.4 \mu m, which is upconverted to 1.2 \mu m by sum-frequency
generation in orientation-patterned GaAs with the output of a standard
high-power cw 1.5 \mu m fiber laser. Both the 1.2 \mu m and the 1.5 \mu m waves
are measured by a standard Er:fiber frequency comb. Frequency measurement at
the 100 kHz-level, stabilization to sub-10 kHz level, controlled frequency
tuning and long-term stability are demonstrated.
[Show abstract][Hide abstract] ABSTRACT: Progress in processing low-loss quasi-phase-matched gallium arsenide crystals makes it possible to benefit from their excellent nonlinear properties in practical mid-infrared sources. This paper addresses both crystal growth aspects and the most recent device demonstrations.
[Show abstract][Hide abstract] ABSTRACT: Progress in processing low-loss quasi-phase-matched gallium arsenide crystals allows their excellent nonlinear properties to be employed in practical mid infrared devices. This presentation will address both crystal growth aspects and the most recent devices demonstrations.
[Show abstract][Hide abstract] ABSTRACT: Due to a wide transparency range (0.9-17 mum), a low absorption loss (~ 0.01 cm-1), and a laser damage threshold comparable to ZGP crystals (~ 2 J/cm2), combined with excellent nonlinear, thermal and mechanical properties, quasi-phase-matched orientation-patterned gallium arsenide (OP-GaAs) crystals are well adapted for efficient mid-infrared optical parametric oscillators (OPOs). The paper discusses the best results obtained, to our knowledge, with an OP-GaAs OPO pumped by a Qswitched 2.09 mum Ho3+:YAG laser. The compact (33 × 48 cm) high-repetition rate source developed allows to achieve 4.0 W of average output power in the 3-5 mum range at 40 kHz repetition rate with a 45 % slope efficiency and a very good beam quality (M2 < 1.8). 6.4 W were obtained at 70 kHz with a 51 % slope efficiency, and 7.7 W at 100 kHz with a 46 % slope efficiency. At 40 kHz and 70 kHz, an optical damage occurred at a fluence of 1.9 J/cm2 and 1.5 J/cm2 respectively. The power is limited by the OP-GaAs crystal thickness and is expected to be scaled in thicker samples recently fabricated.
Proceedings of SPIE - The International Society for Optical Engineering 10/2011; 8187. DOI:10.1117/12.898118 · 0.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Among quasi-phase matching (QPM) materials, PPLN suffers from a limited transparency, strongly limiting both the output power and the beam quality above 4 mu m. We are developing a new QPM technology based on Orientation-Patterned Gallium Arsenide (OP-GaAs) crystals, transparent up to 16 mu m and showing excellent nonlinear and thermal properties and very low losses (< 0.02 cm(-1)). We demonstrated with such samples a high-repetition rate tunable OPO attractively pumped by a remote Thulium fiber laser and integrated in a 25x30x6 cm transportable head. A 3 W level output in the 3-5 mu m range was obtained with a 53% efficiency and an unprecedented beam quality (M(2)=1.4), making this module most suited to study directed infrared countermeasures (DIRCM).
Proceedings of SPIE - The International Society for Optical Engineering 10/2010; 7836. DOI:10.1117/12.865065 · 0.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We demonstrate what is to our knowledge the first realization of an optical parametric amplifier in orientation-patterned GaAs amplifying the emission of a quantum-cascade laser (QCL) with a distributed-feedback (DFB) structure. We report a gain as high as 53 dB at 4.5 mum, in good agreement with theoretical calculations. The narrow spectral linewidth and the good beam quality of this source are imposed by the DFB-QCL, while high-peak-power emission is achieved through the parametric amplification. These characteristics are of valuable interest for long-range spectroscopy.
[Show abstract][Hide abstract] ABSTRACT: A widely tunable difference frequency generation based mid-infrared spectrometer for the detection of sulfur dioxide (SO2), nitrous oxide (N2O), and methane (CH4) above 7 µm has been developed for industrial applications.
Laser Applications to Chemical, Security and Environmental Analysis; 01/2010
[Show abstract][Hide abstract] ABSTRACT: The effects of coupling between clockwise and counterclockwise modes in ring resonators due to back reflections from QPM gratings
in nonlinear crystals are investigated. We demonstrate, using simulations, that the non-phase-matched back reflection due
to typical imperfections of the QPM grating has a relevant magnitude and can give rise to the coupling. We developed an analytical
model and evaluated parameters of a singly resonant OPO in the presence of this coupling, which indicates that the threshold
pump power is doubled in the limit of strong coupling. We also evaluated the effect of the coupling with respect to resonant
power enhancement for cavity-enhanced nonlinear frequency mixing applications, finding that the enhancement is reduced by
up to a factor four. Experimental observations based on PPLN and orientation-patterned GaAs crystals and model predictions
are in good agreement. We propose and demonstrate a method for active stabilization of ring resonators with mode coupling
that relies on the dissimilarity of the coupled forward and backward modes.
Applied Physics B 01/2010; 100(4):737-747. DOI:10.1007/s00340-010-4178-4 · 1.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this article we address the design and exploitation of a real field laboratory demonstrator combining active polarimetric and multispectral modes in a single acquisition. Its buildings blocks, including a multi-wavelength pulsed optical parametric oscillator at emission side, and a hyperspectral imager with polarimetric capability at reception side, are described. The results obtained with this demonstrator are illustrated on some examples and discussed.
Proceedings of SPIE - The International Society for Optical Engineering 05/2009; 7323. DOI:10.1117/12.820052 · 0.20 Impact Factor