Nonlinear optical absorption in semiconductor epitaxial depletion regions.
The optical nonlinearities in unbiased epitaxial Schottky barrier depletion regions have been studied. It has been shown that the high electric fields in the depletion region can be modulated by photogenerated carriers trapped in the region. The decrease in internal electric field with applied light leads to large changes in the absorption of the device at low input optical power. This effect is used as the basis of a depletion region electric-field absorption modulator (DREAM), which lies between intrinsic and hybrid linear optical devices in that, although the effects of industry are induced by an electric field, there is no external circuit applied to the device. The demonstrated device consists of a semi-insulating InP(Fe) substrate which is transparent to the 1.06-μm (hv = 1.17eV) Nd:YAG wavelength used to probe the InGaAsP epilayer. Due to the simplicity of this device, it was possible to grow the 0.3-μm thick epilayer using liquid-phase epitaxy.