Research On Micro-Ring Based Integrated Demulitiplexing And Receiving Technology Of WDM Systems

The research described in this paper is supported by grants from The National Basic Research Program of China (No. 2003CB314902, 2003CB314902), Program for New Century Excellent Talents in University of China (No. NCET-05-0111), National Natural Science Foundation of China (No. 60576018, 90601002), Program of Key International Science and Technology Cooperation Projects (No. 2006DFB11110).Recently, optical microresonators attracted much attention and have been extensively studied. Devices such as microring, microdisk and microsphere are compact and easy to be integrated, which are widely used as laser resonator, optical filter etc. However, there are not many studies in photodetectors based on microresonator (MRPD), the photodetectors based on microring resonator solely made of semiconductor material is also not achieved at present. MRPD combining the advantages of waveguide photodetetor and Resonant-Cavity Enhanced (RCE) photodetector has the characteristics of compactness, easy planar integration, capable of selecting wavelength, high speed and high quantum efficiency which have bright application future in the Optics Electronics Integrate Circuit (OEIC) and Dense Wavelength Division Multiplexing (DWDM) optical communication system.The detailed theoretical analysis, parameter design and experimental grope of MRPD are carried out. The main achievements in this paper are listed as follows.1. The coupling coefficient between micro-ring waveguide and straight waveguide is analyzed using coupled mode theory. The effective absorption coefficient of MRPD is analyzed using BPM (Beam Propagation Method) in RSOFT. Then the quantum efficiency of MRPD is computed. The quantum efficiency, FWHM, FSR of the designed MRPD can reach 0.93, 23nm, 0.4nm respectively.2. The transient response of MRPD is analyzed using time-domain analysis method, moreover the series resistance and junction capacitance are considered synthetically. The relation between the transient response and design parameters is derived.3. The micro-ring and the micro-racetrack photodetector which contain the InGaAs absorption layer are fabricated with the material of InP/InGaAsP together with Doctor Haibo Chen. The spectrum of throughout port is measured. For microring photodetector whose radius is 80μm, the FSR is 0.75nm and FWHM is 0.5nm. For the micro-racetrack photodetector whose radius is 80μm and the length of straight waveguide which connects to the arc is 30μm, the FSR is 0.7nm and FWHM is 0.4nm.4. The possibility of polygon resonator photodetector is studied. This kind of photodetector is composed of straight waveguide and polygon resonator waveguide, such as micro-triangle waveguide, micro-square waveguide. The coupling in the photodetector is between two straight waveguides, so the coupling coefficient is easy to analyze and the gap between waveguides could be wider for certain coupling coefficient. The quantum efficiency of triangle resonator photodetector is computed. In certain condition, the quantum efficiency can reach 0.903 and the FWHM, FSR are 24nm, 0.4nm respectively.