Intensity-dependent reflectance and transmittance of semiconductor periodic structures

The intensity-dependent response of nonlinear Bragg-periodic epitaxially-grown InGaAs-InAlGaAs-based optical elements is reported over a broad spectral range 1.3-1.6 mum. Large changes in the transmittance and reflectance are observed as a function of incident power. Over most of this spectral region, the nonlinear response is dominated by the saturation of absorption. In the vicinity of 1.5 mum, the optical elements exhibit fluence-dependent Bragg diffraction. For low incident powers, the indices of refraction of structures are uniform and no coherent scattering takes place. With increased incident power a Bragg grating appears, resulting in the emergence of a fluence-dependent stopband in the transmittance and reflectance spectra.