Gilles Feugnet

High-efficiency TEM 00 Nd:YVO 4 laser longitudinally pumped by a high-power array

A new simple, compact, and efficient optical device is presented that allows any commercially available arrays or stacks to longitudinally pump laser materials. A Nd:YVO(4) laser was built and an optical-optical efficiency as great as 50% was demonstrated with a diffraction-limited beam.

High-efficiency TEM{sub 00} Nd:YVO{sub 4} laser longitudinally pumped by a high-power array

A new simple, compact, and efficient optical device is presented that allows any commercially available arrays or stacks to longitudinally pump laser materials. A Nd:YVO(4) laser was built and an optical-optical efficiency as great as 50% was demonstrated with a diffraction-limited beam.

Efficient degenerate four-wave mixing in a diode-pumped microchipNd:YVO 4 amplifier

The process of saturable-gain degenerate four-wave mixing in a diode-pumped microchip Nd:YVO(4) amplifier is investigated. To enhance the efficiency of the interaction, multipass geometries are employed in which the weak signal beam and therefore the conjugate beam experience several passes in the gain medium. Degenerate fourwave mixing reflectivities as high as R = 10% and R = 170% have been obtained experimentally for 130-W diode pumping with two-pass and four-pass geometries, respectively. Finally, the imaging capabilities of the volume population hologram written in the Nd:YVO(4) amplifier are demonstrated.

Multipass degenerate four-wave mixing in a diode-pumped Nd:YVO 4 saturable amplifier

The process of saturable-gain four-wave mixing (DFWM) in a diode-pumped Nd:YVO4 amplifier with interacting beams provided by a Nd:YAG oscillator is investigated. Multipass geometries are employed that arrange for the signal beam to experience an increased interaction length relative to that of the pump beams. DFWM reflectivities up to R = 170% and a diffraction efficiency η = 6% of the volume population hologram written in the Nd:YVO4 amplifier are obtained experimentally. A theoretical analysis of multipass DFWM is presented in the transient (pulsed) regime, including the laser amplification and the mutual interaction of all the interacting beams as well as the spectral mismatch between the beam frequency and the gain line-center frequency of the Nd:YVO4 amplifier. It is shown that because of the close spectral matchup of the Nd:YAG oscillator and the Nd:YVO4 amplifier, the amplitude (gain) grating contribution is predominant compared with that of the phase grating.

Mode-Coupling Control in Resonant Devices: Application to Solid-State Ring Lasers

We report the theoretical and experimental investigation of the effects of mode coupling in a resonant macroscopic quantum device, in the case of a solid-state ring laser. This is achieved by introducing an additional coupling source whose interplay with the already-existing nonlinear effects ensures the coexistence of two counterpropagating cavity modes yielding a rotation-sensitive beat note. The determination of the condition for rotation sensing, both theoretically and experimentally, allows a quantitative study of the role of various mode-coupling mechanisms, in particular, the gain-induced mode coupling. We point out the connection between our work and the theoretical work on mode coupling in superfluid devices. This work opens up the possibility of new types of active rotation sensors.

Single-frequency external-cavity semiconductor ring-laser gyroscope.

We report for the first time (to our knowledge) the experimental achievement of a single-frequency ring-laser gyroscope using a diode-pumped half-vertical-cavity semiconductor-emitting laser structure as a gain medium. Thanks to the control of mode competition by an active feedback loop, we observe a beat signal from recombined beams that has a frequency proportional to the rotation rate as predicted by the Sagnac effect. This promising result opens new perspectives for rotation sensing.

8-mJ TEM 00 diode-end-pumped frequency-quadrupled Nd:YAG laser

A frequency-quadrupled Nd:YAG laser pumped by a commercially available high-brightness stack is described. A master oscillator power amplifier configuration was implanted, and the laser delivered energy of 8 mJ at 0.266microm . The laser was air cooled for easy use.

Large-field-of-view, high-gain, compact diode-pumped Nd:YAG amplifier

We present a compact diode-end-pumped Nd:YAG amplifier with a FWHM angular bandwidth of 100 degrees . Using a 1.064-microm probe beam, we measured a 2-pass gain of 23 (13.6dB) and a 4-pass gain of 420 (26.2dB). High-gain image amplification with such a laser amplifier is also demonstrated.

Oscillation regimes of a solid-state ring laser with active beat-note stabilization: From a chaotic device to a ring-laser gyroscope

We report an experimental and theoretical study of a rotating diode-pumped Nd-YAG ring laser with active beat-note stabilization. Our experimental setup is described in the usual Maxwell-Bloch formalism. We analytically derive a stability condition and some frequency response characteristics for the solid-state ring-laser gyroscope, illustrating the important role of mode coupling effects on the dynamics of such a device. Experimental data are presented and compared with the theory on the basis of realistic laser parameters, showing very good agreement. Our results illustrate the duality between the very rich nonlinear dynamics of the diode-pumped solid-state ring laser (including chaotic behavior) and the possibility to obtain a very stable beat note, resulting in a potentially new kind of rotation sensor.

Solid-state ring laser gyro behaving like its helium-neon counterpart at low rotation rates

Nonlinear couplings induced by crystal diffusion and spatial inhomogeneities of the gain have been suppressed over a broad range of angular velocities in a solid-state ring laser gyro by vibrating the gain crystal at 168 kHz and 0.4 microm along the laser cavity axis. This device behaves in the same way as a typical helium-neon ring laser gyro, with a zone of frequency lock-in (or dead band) resulting from the backscattering of light on the cavity mirrors. Furthermore, it is shown that the level of angular random-walk noise in the presence of mechanical dithering depends only on the quality of the cavity mirrors, as is the case with typical helium-neon ring laser gyros.