Acousto-optic laser optical feedback imaging

We present a photon noise and diffraction limited imaging method combining the imaging laser and ultrasonic waves. The laser optical feedback imaging (LOFI) technique is an ultrasensitive imaging method for imaging objects through or embedded within a scattering medium. However, LOFI performances are dramatically limited by parasitic optical feedback occurring in the experimental setup. In this work, we have tagged the ballistic photons by an acousto-optic effect in order to filter the parasitic feedback effect and to reach the theoretical and ultimate sensitivity of the LOFI technique. We present the principle and the experimental setup of the acousto-optic laser optical feedback imaging (AO-LOFI) technique, and we demonstrate the suppression of the parasitic feedback

Plenoptic microscope based on laser optical feedback imaging (LOFI)

We present an overview of the performances of a plenoptic microscope which combines the high sensitivity of a laser optical feedback imaging setup , the high resolution of optical synthetic aperture and a shot noise limited signal to noise ratio by using acoustic photon tagging. By using an adapted phase filtering, this microscope allows phase drift correction and numerical aberration compensation (defocusing, coma, astigmatism ...). This new kind of microscope seems to be well adapted to make deep imaging through scattering and heterogeneous media

The hypothesis of the moving comb in frequency shifted feedback lasers

International audienceThe use of frequency-shifted feedback (FSF) lasers in optical metrology is based on a unique coherence property: the appearance of beats in the noise spectrum at the output of a two-beam interferometer, whose frequencies vary linearly with the path delay of the interferometer. A description of the output of a FSF laser as a moving comb of optical frequencies is generally admitted to explain these specific coherence properties. Here starting from the model of a passive FSF cavity seeded by spontaneous emission we give a rigorous description of the time-spectrum properties of FSF lasers and show that the moving comb exists only in the limit of small frequency shift

Study of a circular Gaussian transition in an optical speckle field

We propose a numerical approach to study optical speckle fields generated by various conditions of surface roughness and illumination, without any a priori assumption concerning the properties of the scattered field. By overcoming the limitations imposed by the use of the central limit theorem, we perform the study of the whole circular Gaussian transition undergone by the speckle field when varying the surface roughness and the size of the laser illumination. We focus our attention on the speckle contrast, the degree of circularity and the degree of assymmetry, including their radial dependence

Transient and modulation dynamics of an erbium fiber laser

No abstract availabl

Imagerie laser par re-injection optique

En optique, l'interférométrie est un outil extrêmement puissant permettant des mesures de distance, de vitesse, de vibration, $\ldots$avec une excellente précision. D'un autre coté, les lasers sont extrêmement sensibles à la rétroaction optique. Nous avons combiné ces deux propriétés pour développer au laboratoire de nouvelles méthodes d'imagerie basées sur le comportement dynamique des lasers

SPECTRAL AND TEMPORAL BEHAVIOR OF AN ERBIUM DOPED FIBER LASER

The dynamics of an erbium doped fiber laser are analysed under continuous and modulated pumping. It is found that the bondaries between different modes depend only on the pump parameter and the lifetime of the photon in the cavity. Spectral and temporal behaviors are analysed