Alain Azema

Bolometric photoresponse of superconducting YBa2Cu3O7-x/La2CuO4 multilayers to infrared radiation

We report bolometric photoresponse of YBa2Cu3O7-x thin film and YBa2Cu3O7- x/La2CuO4 multilayers at temperature of liquid nitrogen irradiated by a semiconductor laser diode at 0.83 microns. We develop a heat transfer model which takes into account the lateral diffusion of heat in the substrates. Using this model we explain the time dependence of the photoresponse. From the analysis of the photoresponse voltage versus time we calculate the optical absorption of the YBa2Cu3O7- x/La2CuO4 multilayers and of the YbaCuO monolayer.

Interplay between photons and superconductors

Reviews theoretical and experimental studies of superconductor-light interactions with the emphasis on the electrical response of high critical temperature superconductors to optical radiation, especially in the visible light and infrared wavelength range.

ArF Excimer Laser Ablation Of Mercury Cadmium Telluride Semiconductor (MCT)

A UV photoablation method with an ArF excimer laser has been experimented on Mercury Cadmium Telluride alloys. We have investigated etching rate, surface quality and surface composition under several experimental conditions. We have also obtained linear photoablated grooves by sample scanning which could be a first step to convert planar into strip waveguides.

Assisted Arf Excimer Photo-Etching Of Mercury Cadmium Telluride (MGT) Semiconductor

UV excimer etching could be an alternative method to classical lithography for the conversion of MOT planar waveguides into strip waveguides. Some preliminary results are given, which concern HgCdTe photoablation by ArF excimer laser emitting at 193 nm, under inert or chemically active surrounding gas conditions.

Caractérisation de HgCdTe en couche mince à 10,6 μm

AnalyseLes guides obtenus par diffusion de mercure dans un substrat de tellurure de cadmium sont à gradient d’indice. L’étude des lignes noires permet d’en mesurer le profil d’indice de réfraction. A partir de données bibliographiques reliant l’indice de réfraction à la concentration de cadmium, on déduit le profil de concentration. La précision de la mesure permet de mettre en évidence, sur quelques échantillons, une flèche de fabrication de 10 μm sur 5 mm. Les mesures d’affaiblissement de l’onde infrarouge guidée sur une distance de quelques millimètres permettent d’annoncer un affaiblissement inférieur à 0,5 dB/cm à 10,6 μm. La tenue en puissance des guides a été testée à des densités de l’ordre de 10 kW/cm2 en continu.AbstractHg-diffusion in a CdTe substrate leads to a graded index waveguide. M-lines analysis gives the refractive index profile of these guides. From published data giving refractive index versus cadmium concentration, we deduce the concentration profile. Measurement accuracy enables to show a fabrication bending on some samples of 10 μm/5 mm. The propagation of a 10.6 μm wave exhibits an exceptionnally low attenuation (<0.5 dB/cm) on all modes. Up to 10 kW/cm2 — cw power density has been guided without damage.