Optically Controlled Absorption Of InGaAsP Epitaxial Layers For Parallel Optical Data Processing And Dynamic Holographic Gratings

Abstract

We investigate all-optical transmission control of InGaAsP epilayers on InP substrates by optical generation of excess carriers. A modulation depth of more than 40% is achieved at the near-band-gap wavelength of λt = 1.3μm of the 2μm thick epilayer at a power of a few mW in the control beam of λc = 790nm wavelength. The maximum bit rate is limited by excess carrier lifetimes to ca. 100 Mbit/s. Several channels can be operated in parallel. At a distance of 25pm between adjacent spots crosstalk between channels is less than -202 dB. Considering the low power dissipation a density in the order of several 100 channels/mm can be processed in parallel making this device attractive for all-optical data processing. We have used the capabilities of spatial light modulation to demonstrate dynamic holographic beam deflection. A theoretical analysis of the optical transmission control based on dynamic band filling in parabolic bands and direct electronic transitions provides a good description of the experiments.