I. Ribet

Dual-cavity doubly resonant optical parametric oscillators: demonstration of pulsed single-mode operation

The operating points of pulsed dual-cavity doubly resonant optical parametric oscillators have been investigated, taking into account the influence of the optical dispersion. A diagram is proposed to determine the spectral separation of doubly resonant positions for any optical lengths of both cavities. From the analysis of the distribution of doubly resonant coincidences, original conditions for stable single-mode operation are specified. This approach is validated by use of a type II phase-matched β-barium borate crystal. Frequency stability and tuning characteristics are also reported. To our best knowledge, this is the first demonstration of single-mode operation that uses a dual-cavity doubly resonant optical parametric oscillator in the nanosecond pulsed regime.

Widely tunable single-frequency pulsed optical parametric oscillator

The spectral output of a nanosecond dual-cavity doubly resonant optical parametric oscillator has been investigated versus the relative length of the signal and idler cavities. Regions of stable single-frequency operation are determined by use of a type II phase-matched KTP crystal and compared with the predictions of a mode-overlap model. A wide mode-hop-free tuning range is obtained over 40 GHz, limited only by piezoelectric biases. Furthermore, discrete tuning is investigated over the full parametric gain curve. For demonstration purposes, experiments are performed in the domain that is most inclined to multifrequency emission, i.e., near degeneracy.

Experimental and theoretical investigation of the off‐band spectral response of quantum well infrared photodetectors

High dynamics measurements of spectral response were carried out on quantum well infrared photodetectors (QWIP). This experiment revealed the presence of spectral structures which were never observed hitherto. Electric field assisted tunneling and, more surprisingly, Van Hove singularities at the miniband edges, have been observed in the low and high energy parts of the QWIP photocurrent spectra, respectively. These experimental features motivated us to initiate a theoretical study of the absorption in a multiquantum well structure.

Semi-monolithic optical parametric oscillator: infrared pulsed single-longitudinal-mode operation

Summary from only given. The multi-frequency behavior of pulsed OPOs is detrimental for most of applications that require a typical line width of 100 MHz. To fulfill the spectral need, dual-cavity doubly resonant optical parametric oscillators (DROPOs) are well suitable since they provide a low threshold of oscillation in combination with compactness. We report here a novel compact nanosecond OPO leading to single- longitudinal-mode output from a semi-monolithic linear dual-cavity DROPO operating at several kHz in the mid-infrared domain.

HYPERSONIC BOUNDARY LAYER ANALYSIS COMPARISON OF VELOCI TY MEASUREMENTS AND MONTE -CARLO CALCULATIONS

* Research scientist, Theoretical and Applied Optics Department. † Research scientist, Fundamental and Experimental Aerodynamics Department. ‡ Senior research scientist, Physical Instrumentation and Sensing Department. § Scientific director, Office National d’Etudes et de Recherches Aerospatiales. ¶ Senior research scientist, Institute of Theoretical and Applied Mechanics. # Professor, Institute of Theoretical and Applied Mechanics. Associate fellow. INTRODUCTION

Dual-cavity DROPO - an ideal single-mode source for nonlinear spectroscopy

Summary form only given. With the appearance of periodically poled crystals, tremendous developments were recently obtained in the field of continuous-wave (cw) optical parametric oscillators. However, the low power delivered by cw sources is not appropriate to address the problems of nonlinear spectroscopy and open air pollutant species detection. Pulsed OPOs seem to be a good alternative for such applications since high output power can be delivered over a large domain of wavelengths from rugged and compact devices. Nonetheless, the broad spectral bandwidth of nanosecond-duration pulsed OPO remains a serious drawback for spectroscopic purposes. In this paper, we propose a new alternative, based on a dual-cavity doubly resonant OPO (DROPO).Using two separate cavities allows us to prevent oscillation with imperfect mode overlap.

Pulsed single-mode doubly resonant optical parametric oscillator based on the Vernier effect

Summary form only. Nanosecond pulsed optical parametric oscillators (OPOs) are very attractive sources for numerous applications of spectroscopy provided that stable single-mode operation is obtained. Although the output of a Q-switched OPO is naturally multimode, we show here that pulsed single-mode output can be achieved from a compact and rugged device based on a dual-cavity DROPO (doubly resonant optical parametric oscillator). This is of particular importance for pollutant detection and for nonlinear spectroscopy applications such as four-wave mixing diagnostics.

Optical parametric oscillator for flow diagnostics

Abstract Cluster hopping effects and frequency instabilities prevent a wide use of doubly-resonant optical parametric oscillators (DROPOs) in the field of optical diagnostics, especially in the nanosecond regime. By using a two-cavity device, we demonstrate here that stable single-mode output can be obtained, provided that the length of each cavity is carefully chosen.