Russell J. Gehr

Numerical models of broad bandwidth nanosecond optical parametric oscillators

We present three new methods for modeling broad-bandwidth, nanosecond optitcal parametric oscillators in the plane-wave approximation. Each accounts for the group-velocity differences that determine the operating linewidth of unseeded optical parametric oscillators, and each allows the signal and idler waves to develop from quantum noise. The first two methods are based on split-step integration methods in which nonlinear mixing and propagation are calculated separately on alternate steps. One method relies on Fourier transforming handle propagation, wiih mixing integrated over a the fields between t and u to Az step: the other transforms between z and k= in the propagation step, with mixing integrated over At. The third method is based on expansion of the three optical fields in terms of their respective longitudinal empty cavity modes, taking into account the cavity boundary condi- tions. Equations describing the time development of the mode amplitudes are solved to yield the time dependence of the three output fields. These plane-wave models exclude diffractive effects, but can be readily extended to include them.

Nonlinear optical properties of thin film composite materials

Several groups have proposed the use of composite materials as a means of achieving large values of the third-order susceptibility /spl chi//sup (3/). One proposal involves forming a composite of alternating layers of two different materials with layer thicknesses much smaller than an optical wavelength. The angular dependence of the nonlinear optical response of this material can offer a means to determine quantitatively the extent to which the /spl chi/((3)) susceptibility is enhanced. In the present paper, we report the results of our experimental study of this angular dependence. We find that the angular dependence is in good qualitative agreement with theoretical predictions.<<ETX>>