Highly efficient resonant length integrated optic photodetector

Abstract

Abstract A novel integrated optic photodetector with resonant length is theoretically proposed for detection at 1.55 μm. The structure consists of substrate/waveguide/phase matching layer (low index)/absorbing semiconductor layer/air. A general mode expansion and propagation technique based on supermode analysis is used to study the propagation of modes in the device structure. Periodic coupling between the guided mode and the mode supported by the absorbing layer takes place and varies with the length of the detector. We show that resonant coupling between the two super modes takes place for the optimized thickness of the phase matching layer and the absorbing layer at a particular length of the detector which is considered the detector length. An attenuation exceeding 170 dB could be obtained for a detector length of 13 μm for TM polarization. The proposed photodetector exhibits a 3dB bandwidth exceeding 300 GHz and has capacitance of only 0.01 pF. Similar results have been obtained for TE polarization with different thickness of the absorbing layer.