Leonel P. Gonzalez

Accurate evaluation of nonlinear absorption coefficients in InAs, InSb, and HgCdTe alloys

We present a full band structure calculation of temperature- and wavelength-dependent two-photon absorption (TPA) coefficients and free carrier absorption (FCA) cross sections in InAs, InSb, and Hg1−xCdxTe alloys. The wavelength dependence of the TPA coefficients agrees well with a widely used analytical expression. However, the magnitudes of the TPA coefficients obtained here are smaller by a factor of 1.2–2.5 than the analytical values. In addition, the TPA coefficient is found to depend sensitively on the photoexcited carrier density in small gap materials. The FCA is found to arise predominantly from hole absorption. The FCA cross section is found to be independent of the carrier density, but is strongly dependent on the temperature. The calculated TPA, FCA coefficients, and lifetimes are fitted to closed-form expressions and are used in solving the rate equations to obtain the transmitted pump and probe intensities as functions of incident intensity and sample thickness. The calculated pump transmiss...

Second harmonic generation in CdSiP2

A new nonlinear optical crystal, CdSiP2, has recently been developed and a bulk crystal cut for phase-matching of second harmonic generation from 4.8 to 2.4 μm has been tested. Numerical and theoretical results are presented. Accounting for Fresnel losses, internal conversion efficiency was over 55% at a peak incident irradiance of 56 MW/cm2.

An effective z-stretching method for paraxial light beam propagation simulations

A z-stretching finite difference method is developed for simulating the paraxial light beam propagation through a lens in a cylindrically symmetric domain. By introducing a domain transformation in the z-direction, we solve the corresponding complex difference equations containing an interface singularity over a computational space for great simplicity and efficiency. A specially designed matrix analysis is constructed to the study the numerical stability. Computational experiments are carried out for demonstrating our results.

Efficient Mid-Infrared Optical Parametric Oscillator Based on CdSiP 2

We report the first optical parametric oscillator based on the new mid-infrared nonlinear optical crystal CdSiP2. Pumping with a 2W, 1.99-micron Tm:YALO laser produced 340 mW average power output (signal + idler) at 27% slope.

Measurement of the nonlinear optical properties of semiconductors using the irradiance scan technique

Irradiance scan measurements of the nonlinear absorption and refraction coefficients of CdTe were performed at room temperature and at 77 K and compared to the values obtained in previous experiments using a different technique.

Measurement of optical and thermal properties of Hg1-xCdxTe

Measurements of optical transmission and several thermal properties of Hg(1-x)Cd(x)Te alloys are reported for a few values of the alloy composition parameter x, which was determined by a microprobe technique. The values of the thermal diffusivity, specific heat, and thermal conductivity were measured using the laser-flash method. These results are reported at four discrete temperatures between 90 and 400 K and compared to those of three well-characterized semiconductor materials: Si, InAs, and InSb.

Temperature and wavelength dependence of the nonlinear optical parameters of InP

Values of the nonlinear absorption and nonlinear refraction coefficients of InP were measured at different temperatures using picosecond and nanosecond durations lasers operating at 1064 nm and 1570 nm.