Design of ultra-fast dual-wavelength resonant-cavity-enhancedSchottky photodetectors

A systematic optimization procedure for the design of RCE Schottky photodetectors to achieve maximum quantum efficiency and high speed operation at 1.3 and 1.55 μm wavelengths is presented. The quantum efficiency formulation used includes the structural parameters of the photodetector and takes into account the wavelength dependence of the top and bottom mirrors reflectivities. The results have shown that the value of the thickness of the antireflection coating layer has a major influence in selecting the width of the photodetector to simultaneously achieve maximum quantum efficiency and high bandwidth at the two wavelengths. Simulated values of 270 and 40 GHz were obtained, respectively, for the 3-dB carrier-transit time-limited bandwidth and bandwidth-efficiency product for an RCE Schottky photodetector with a 0.02-μm gold layer