Sublattice inversion epitaxy of compound semiconductors for quadratic nonlinear optical devices

Compound semiconductors have not attracted much attention as materials for quadratic nonlinear optics such as frequency doubling and parametric amplification because most semiconductors are optically isotropic and hence do not allow phase matching required for efficient nonlinear optical processes. This is, however, unfortunate in view of the large optical nonlinearities exhibited by a number of semiconductors. Furthermore, the sophisticated crystal growth and fabrication technologies available for semiconductors might make it possible monolithically to integrate semiconductor-based nonlinear optical devices with laser diodes, thus opening up a new possibility of compact laser sources. To exploit this potential requires spatial modulation of the optical nonlinearity, which should enable quasi phase matching. The ideal method to exploit the optical nonlinearity of semiconductors is to achieve crystal domain inversion, resulting in sign reversal of the nonlinear optical coefficient. Yoo et al. (1995) reported periodic domain inversion of AlGaAs by use of wafer bonding followed by overgrowth. In the paper, we present an alternative, and potentially more versatile, technique to achieve domain inversion in compound semiconductors.