High Efficiency and High Bandwidth Double-Cladding Waveguide Photodetector Array for 400 Gbit/s Communication

Abstract

A parallel array of 10 side-illuminated waveguide photodetectors (WGPDs) with double-cladding structure was designed and fabricated. In order to achieve high coupling efficiency to the fiber, the thicknesses of InGa0.24As0.53P cladding layers and In0.53Ga0.47As core layer were optimized. The array exhibited a uniform responsivity of 0.54 A/W at 1310 nm without anti-reflection (AR) coating and dark currents lower than 1.3 nA at −5 V. Each photodetector (PD) showed a bandwidth of over 30 GHz, amounting to 400 Gbit/s transmission capacity for the whole chip. In addition, numerical analysis showed that the fiber alignment tolerance to the chip edge along vertical and horizontal directions, when using a lensed fiber, were 1.8 μm and 4.6 μm, respectively. The simple fabrication, easy alignment capability and high performance make the photodetector array a competitive solution for future 400 Gbit/s parallel communication.