Research On Tunable Photodectors And Optical Receiver Circuit For Optical Communication System

With the rapid development of optical fiber communications, higher speed and capacity are required. Wavelength division multiplexing (WDM) takes full advantage of the bandwidth resources of the fiber and greatly improves the transmission speed. It has been developed rapidly in backbone network, metropolitan area network and access network. Wavelength demultiplexing and receiving technology is one of the key technologys in WDM system. Multiplexer/demultiplexer with wavelength-tunable can achieve routing dynamically, it has been used widely in reconfigurable optical add-drop multiplexer (ROADM) system. The discrete combinations of demultiplexer and photodetector have a lot of disadvantages:high cost, large size, additional insertion loss and etc. In this context, the integrated demultiplexing receiver with high quantum effciency, high speed and wavelength-tunable has become the focus in the area of the optical communication.The optical receiver using the photodector with wavelength-tunable can achieve the functions of demultiplexing, filtering and detecting. It has the potential advantages in simplifying the network design, improving the integration of the network equipment and reducing the cost of the net building.This dissertation is mainly concerned with demultiplexing receiver in WDM system, tunable photodector and the design of the optical receiver. The main work is list as follow:1. The development of demultiplexing receiver and high speed optical receiver in the optical fiber communications were thoroughly investigated. The integrated photodectors with wavelength-selection and wavelength-tunable were analyzed. 2. A new tunable RCE photodector with air-layer structure was presented. The air gap is inserted into the F-P cavity, the length of the F-P cavity is changed by adding the tuning voltage. Simulation results show that the maximum quantum efficiency of this photodetector is 98.5% while the thickness of absorption layer is 194nm and air layer is 24.8μm. When the thickness of the air layer is changed 20nm, the peak wavelength blue shifts 1.1 nm. In the tuning process, the peak quantum efficiency of this structure keeps almost invariant. For this structure, the tunable principle is simple and it is easy to realize. The new designed device not only has high quantum efficiency, but also the wavelength and bandwidth can be tuned independently.3. The design scheme of high-speed optical receiver using the photodector with wavelength-tunable was proposed. In order to achieve wavelength-tuning and the stability of the centre wavelength, the tuning module and the temperature control module were added based on the conventional optical receiver in this sheme. According to the design theory of the high-speed PCB (Printed Circuit Board) and the principle of the optical receiver, appropriate chips were selected, high-speed optical receiver was manufactured, it s maximum operating rate is lOGbit/s. A measurement platform was built and the experiment of the high-speed optical receiver was carried out. The result demonstrated that the performance of this module is well.