Research On High-speed Characteristics And Measurement Methods Of Photodetectors Used In WDM System

Accompany with the development of optical communication, the quantity of information and the handling speed are increasing. As the essential device of optical communication, PD is becoming research emphasis, as well as improving performances and accurate measurement of it. In this thesis, almost all important parameters of photodetectors and how to measure them are introduced, especially the measurement of frequency response. What's more, a novel method to improve photodetector's high-speed performance is studied, and proved through experiment as well. The main achievements are listed as follows.1. According to those results of measuring many devices with different materials and structures, I analyzed measuring methods of photodetectors's important parameters, such as I-V character, dark current, frequency response, quantum efficiency and tunable performance. A calibration method based on 12-error model is designed to solve the effects brought by probes.2. The measurement method of frequency response using lightwave component analyzer is introduced. The principle and calibration method of this method are studied. We lay out the measurement system and prove it's veracity using standard device. New system of measurement is laid out, and it expands the range of frequency we can measure from 20GHz to 40GHz.3. With the research on the principle of pulse response techniques, we designed and established the system of pulse response measurement. It showed us the different effects on results with pulse width using different sources. After analyzing the results, some suggestions of improving this method are brought up. 4. Analyzing aspects affecting high-speed performance of photodetectors, then using a spiral inductance to improve this performance, it can suppress the negative effects of junction capacitance. The small signal equivalent circuit models of PIN-photodetector have been established. The affectivity of the inductance is observed through changing inductance's value. Adding spiral inductors to devices, we fabricated photodetectors and measured them. From the results, the 3dB bandwidth of PD without inductor can only achieve 2GHz, while those with inductors can achieve 5GHz. This result agreed very well to that of theoretical analysis. A paper about this research has been published on Journal of Optoelectronics·Laser.