High-accuracy measurements of the normal specular reflectance.

The French Laser Megajoule (LMJ) is designed and constructed by the French Commissariat à l'Energie Atomique (CEA). Its amplifying section needs highly reflective multilayer mirrors for the flash lamps. To monitor and improve the coating process, the reflectors have to be characterized to high accuracy.

Characterization of a heat flux sensor using short pulse laser calibration.

A method to calibrate classical heat flux sensors is presented. The classical approach to measure the temperature inside a known material by using a thermocouple fails when the measurement time is very short. In this work the surface heat flux is determined by solving the inverse heat conduction problem using a noninteger identified system as a direct model for the estimation process.

Picosecond photorefractive response of GaAs:EL2, InP:Fe, and CdTe:V.

Measurements and theoretical calculations are presented for the photorefractive effect in three semi-insulating semiconductors (GaAs:EL2, InP:Fe, and CdTe:V) using 29-psec pulses at a wavelength of 1.06 microm. The photorefractive gain is largest in the CdTe crystal and smallest in our InP sample.

Polarization-rotation switch using picosecond pulses in GaAs.

Photorefractive and free-carrier nonlinearities in GaAs transfer energy from a strong picosecond pump, which is linearly polarized at an arbitrary angle to a weak s-polarized probe, into a p-polarized beam propagating in the probe direction. By placing the GaAs between a crossed pair of high-quality polarizers that are set to extinguish the probe in the absence of the pump, an efficient, high-contrast, high-speed optical switch is realized. By varying the pumpprobe ratio, delay, fluence, and polarization, we can maximize the intensity of the p-polarized component.