The Reaserch On Wavelength-Selective Photodetectors For Optical Fiber Communications Dwdm System

At present, due to owning the performances of large capacity, high rate, flexible and reliable telecommunication networks etc., the optical fiber communication DWDM system has been widely used in long-haultransmission of the core network and metropolitan area network. In DWDM system wavelength demultiplexer and photodetector are key devices for the end-user receiving, and the performance of them is rather important to the whole system. Integrated demultiplexing receiver owning the both performances of wavelength demultiplexing and opticaldetection, has advantages of low cost, low power consumption, compactness, high reliability, easy packaging, and so on. It has good application prospect in optical fiber communication.In this dissertation, the photodetector used in DWDM system with the performance of wavelength selection is studied in detail. The main contents achievements of this dissertation are listed as follows:1、The optical field distribution in this new resonant cavity enhanced dual-absorption (RCE-PINIP) structure has been analyzed. Based on this, the quantum efficiency and the standing wave effect (SWE) in the cavity of this photodector have been calculated and simulated in detail. Also the influence of SWE on the quantum efficiency has been analysed.2、Analysis of internal power enhancement factor and wavelength selectivity of RCE-PINIP photodector has been performed. The result shows that at higher mirror reflectivities, for small a(d1+d2) the enhancement factor is far greater than1, yielding a correspondingly high ηdespite the thin active layer. For given top and bottom mirror reflectivities, there is an optimal absorption layer thickness. Meanwhile the interchannel crosstalk attenuation(C) of this wavelength selective photodector has been studied. On this basis, the product ηC which reflects the tradeoff of high C and high ηhas been measured. The simulation result shows that at optimized η(R1-R2e-2a(d1+d2))， the peak product ηC is achieved near a(d1+d2)=0.05(less as R2increases).3、A novel demultiplexing photodetector which consists of a filtering cavity and a conical absorption cavity is proposed. The filtering cavity is formed by four coupled (Fabry-Perot) F-P cavities, which can realize flat-top and steep-edge spectral response. The top mirror of the absorptioli cavity is designed to be conical, which can increase the times of light reflectieion. Then the quantum efficiency is improved. Through the theoretical analysis and simulation, the peak quantum efficiency of the photodetector is88.87%around1550nm. In addition, this photodetector has good performance in the flat-top and steep-edge spectral response:the0.5dB bandwidth is0.4nm, the3dB bandwidth is0.56nm and the20dB bandwidth is0.98nm.4、The RCE-PINIP photodector was successfully fabricated and the spectral response and the frequency response were both measured. The results showed a approximately70%quantum efficiency around1500nm and a3GHz3dB bandwidth.