Research On High-Performance Long-Wavelength Pin Photodetectors Used In Wdm System

Recently, with the vigorous development of Internet technology, social networks, e-commerce and other novel Internet business is gradually blending into people’s lives. However, these novel technologies have also created unprecedented huge amounts of data at the same time. To meet the increasing requirements of network bandwidth, the construction of larger capacity and higher bit rate broadband optical fiber communication system has become the urgent trend. The wavelength division multiplexing (WDM) technology which could significantly increased the characteristics of optical fiber communication system transmission capacity now becomes the best choice to overcome the bottleneck of network performance. As one of the key factors that may determine the performance of WDM system, the PIN photodetector has become a hotspot in the research field of optical fiber communication. These devices have many great advantages such as low cost, high sensitivity, easy to be integrated, and so on.With solid simulation analysis and experimental work on special microstructures and novel reflectors of photodetector, this dissertation has made the following innovation and achievements:1. A novel InGaAs/InP vertical PIN photodetector with a mushroom mesa microstructure based on a Fabry-Perot filter cavity is designed. By establishing the theoretical equivalent model of PIN photodetector, the performance of the device which introduces the mushroom mesa microstructure is thoroughly investigated. The novel microstructure could significantly reduce the effective junction capacitance of the photodetector. According to the simulation results based on Transfer Matrix Method (TMM), the peak quantum efficiency may reach66.32%at1550nm wavelength. The linewidths of the response peaks are around0.8nm, and the3dB bandwidth may achieve55.11GHz.2. A Si-based high contrast gratings which is sensitive to polarization and has high reflectivity over a wide range of wavelength is designed. By analyzing the theoretical model of one-dimensional high contrast gratings, the influences of gratings period, duty cycle and thickness are discussed in detail to get the ideal broadband reflection spectrum. According to the simulation results based on Finite Element Method (FEM), the reflectivity for TE light and the transmittivity for TM light could reach97%and99%respectively over the range of wavelengths from1480nm to1680nm.3. A novel drift-enhanced dual-junction PIN photodetector based on the high contrast gratings mentioned before is designed. The photodetector is integrated over the gratings by the BCB low temperature bonding process to increase the absorption times. The optimal structural parameters are further investigated. The simulation results show that the novel photodetector may reach a maximized3dB bandwidth of39.26GHz and a peak quantum efficiency of79.09%due to the introduction of the high contrast gratings.4. The InGaAs/InP vertical PIN photodetector with a mushroom mesa microstructure is fabricated. The mushroom mesa microstructure is fabricated by wet etching technique. A peak quantum efficiency of1.58%and a3dB bandwidth of1.2GHz are simultaneously achieved around1550nm.