Thermal effects in a single-frequency, fiber laser pumped, nested cavity optical parametric oscillator

International audienceWe investigate thermal effects in a nested-cavity doubly resonant optical parametric oscillator (NesCOPO), pumped by a high repetition rate laser, and the consequences on its spectral characteristics

Parametric Sources for Chemicals and Gas Sensing

International audienceWe present our activities on the development of tunable optical parametric sources for gas sensing. In particular, we introduce the nested cavity OPO, and rapidly tunable OPOs based on aperiodic quasi-phase matching

Comprendre. Détection de gaz par spectroscopie photoacoustique : principe et mise en œuvre

International audienceLa spectroscopie photoacoustique permet la détection de gaz à l’état de traces. Cette technique permet d’allier compacité, sensibilité, rapidité et grande bande passante optique. Pour ces raisons, elle a le potentiel d’être intégrée dans des instruments permettant de répondre à de multiples enjeux liés à l’environnement, la défense, et la sûreté

Quartz Enhanced Photoacoustic Spectroscopy Based on a Custom Quartz Tuning Fork.

We have designed and fabricated a custom quartz tuning fork (QTF) with a reduced fundamental frequency; a larger gap between the prongs; and the best quality factor in air at atmospheric conditions ever reported, to our knowledge. Acoustic microresonators have been added to the QTF in order to enhance the sensor sensitivity. We demonstrate a normalized noise equivalent absorption (NNEA) of 3.7 × 10-9 W.cm-1.Hz-1/2 for CO₂ detection at atmospheric pressure. The influence of the inner diameter and length of the microresonators has been studied, as well as the penetration depth between the QTF's prongs. We investigated the acoustic isolation of our system and measured the Allan deviation of the sensor

The NAOMI GAZL multispecies differential absorption lidar: realization and testing on the TADI gas leak simulation facility

International audienceWe report on a differential absorption lidar, designed for remote detection of CH 4 and CO 2 , based on a single-frequency 1.57-1.65 µm parametric oscillator/amplifier system. The lidar is tested on a controlled gas release facility

Sources paramétriques optiques innovantes à base de semiconducteurs isotropes

Diverses applications, telles que la détection de polluants ou neurotoxiques, nécessitent de disposer de sources optiques accordables intenses dans l infrarouge (IR) moyen (8 12 m). Une voie bien adaptée pour répondre à ces besoins est d utiliser l optique non linéaire pour convertir vers l IR moyen le rayonnement d un laser émettant dans l IR proche. Cependant, les matériaux non linéaires usuels ne peuvent être utilisés pour la bande 8 12 m car ils absorbent au-delà de 4 m. Afin de s affranchir de cette limitation, nous étudions ici l utilisation des semiconducteurs isotropes comme matériaux non linéaires alternatifs. En effet, ces matériaux (GaAs, ZnSe, etc.) présentent de forts coefficients non linéaires, et sont transparents dans l IR moyen. Comme ces matériaux sont isotropes, des techniques de quasi-accord de phase doivent être mises en place pour une conversion non linéaire efficace. La technique choisie ici est celle de la biréfringence de Fresnel. Nous avons étudié cette technique aussi bien d un point de vue expérimental par des expériences de différence de fréquences dans GaAs entre deux faisceaux proche IR accordables (~1,9 m et 2,4 m), que d un point de vue théorique par le développement de nouveaux modèles prenant en compte tous les processus linéaire et non linéaire intrinsèques à la biréfringence de Fresnel. Enfin, cette technique d accord de phase a été appliquée à l auto-différence de fréquences dans les lasers ZnSe:Cr afin de générer une onde IR moyen à partir d un faisceau pompe unique. L onde à 10 m est alors générée par différence de fréquences entre l onde pompe à 1,9 m et l onde laser émise par les ions Cr2+ autour de 2,3 m.Tunable mid-infrared (IR) sources are of high interest for many applications, including chemical monitoring, gas analysis, remote sensing, and IR countermeasures. A promising way to obtain such mid-IR emission is to use optical sources based on parametric conversion in nonlinear materials. However, apart from few materials (ZnGeP2, AgGaSe2, CdSe, ), most of usual nonlinear materials exhibit strong multiphonon absorption beyond 5 m. Therefore, an important issue is to find adequate materials for the 8 12 m band. In this context, semiconductors of the technological mainstream, such as GaAs or ZnSe, are excellent candidates for mid-infrared parametric generation. Indeed, they display high non linear susceptibility and they are transparent from the near-infrared up to 20 m. However, since these materials are isotropic, quasi-phase-matching techniques have to be implemented to get an efficient conversion. Nonetheless, this limitation can be overcome using Fresnel birefringence that takes place at total internal reflection. We present here an experimental and theoretical study of this phase matching technique : difference frequency generation experiments are carried out and new models are developped to take into account all the physical processes involved. We investigate then self-difference frequency mixing in Cr:ZnSe laser using Fresnel phase matching. Taking advantage of both the lasing and nonlinear properties of this material, we demonstrate that 8 12 m radiation can be produced using a single pump beam at 1.9 m. Subsequently, difference frequency mixing between the 1.9 m pump beam and 2.3 m laser beam produces a mid-IR radiation in the 9 m range.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Nested Cavity Optical Parametric Oscillators (NesCOPO) - A tunable frequency synthesizer for Gas Sensing: Oscillateurs paramétriques à cavités imbriquées- Un synthètiseur de fréquence accordable pour la détection de gaz

International audienceNowadays, active optical detection of molecular species is a strong field of research driven by a great number of applications coming from various sectors: environment, industrial process monitoring, defense and security, food industry or biomedical. Active methods provide local or remote gas detection with high species discrimination thanks to the highly selective response of ro-vibrational absorption lines. However, addressing a wide range of molecular signatures with an active method remains challenging since it requires the implementation of a ‘tunable frequency synthesizer’ covering the mid-infrared domain where lie most absorption transitions.This paper deals with an original architecture based on the parametric conversion of a primary radiation delivered in the near infrared from a well mature laser. Taking advantage of the non-resonant feature of the down-frequency conversion process, a wide spectral coverage is obtained (2–10 µm) while a pure radiation is achieved at a low threshold of oscillation thanks to a doubly resonant optical parametric device using two nested cavities. After a general introduction of the principle of mode selection in such a nested cavity optical parametric oscillator, various gas sensing applications which have been performed over the last decade are reported both for local and remote sensing

Nested Cavity Optical Parametric Oscillators (NesCOPO) - A tunable frequency synthesizer for Gas Sensing: Oscillateurs paramétriques à cavités imbriquées- Un synthètiseur de fréquence accordable pour la détection de gaz

International audienceNowadays, active optical detection of molecular species is a strong field of research driven by a great number of applications coming from various sectors: environment, industrial process monitoring, defense and security, food industry or biomedical. Active methods provide local or remote gas detection with high species discrimination thanks to the highly selective response of ro-vibrational absorption lines. However, addressing a wide range of molecular signatures with an active method remains challenging since it requires the implementation of a ‘tunable frequency synthesizer’ covering the mid-infrared domain where lie most absorption transitions.This paper deals with an original architecture based on the parametric conversion of a primary radiation delivered in the near infrared from a well mature laser. Taking advantage of the non-resonant feature of the down-frequency conversion process, a wide spectral coverage is obtained (2–10 µm) while a pure radiation is achieved at a low threshold of oscillation thanks to a doubly resonant optical parametric device using two nested cavities. After a general introduction of the principle of mode selection in such a nested cavity optical parametric oscillator, various gas sensing applications which have been performed over the last decade are reported both for local and remote sensing

Optical parametric oscillators

Optical parametric oscillators are versatile devices for generating a tunable coherent radiation from an incident laser beam. They rely on nonlinear frequency conversion to cover spectral ranges that are poorly or not covered by direct laser emission. This article presents a short overview of the optical parametric oscillators principles of operation, main implementations and related applications