Research On Wavelength-Selective Photodetectors For Dense Wavelength Division Mutiplexing (DWDM) Systerm

Dense Wavelength Division Multiplexing (DWDM) is the technology which is able to take full advantage of the bandwidth of a fiber-optic, especially in the large-capacity, ultra-long haul transmission. Detectors used for DWDM system, featuring both wavelength-selection and high quantum efficiency, large bandwidth and narrow spectral line width has many applications. The main achievements and research works are listed as follows.1. Analysis of light field distribution within a dual-juction PIN RCE photodetector has been performed. On this basis, both the accurate expressions of quantum efficiency and high-speed response have been derived. The performance of wavelength selection has been analyzed. The main parameters affect the dual-junction PIN RCE detector has been optimized. The optimized result shows a 3dB bandwith of 30 GHz with total thickness of intrinsic absorption region equals to 400nm, as well as effective illumination area and peak quantum efficiency to be 900μm2 and 92%, respectively.2. Analysis of transmission characteristics and thermal tuning principles of F-P cavity has been performed. The spectral transmission characteristics of F-P cavity with DBRs as reflectors has been studied. Epitaxial structure of the dual-junction PIN tunable detectorhas been given. The expresstions of the quantum efficiency and high-speed response of the detector have been given respectively. The result shows that the new structure enhance quantum efficiency of 10% than the traditional one.3. The PIN photodetector with improved electrode was successfully fabricated. Testing for the high-speed response was carried out, the result showed the high-speed response of the device with the same structure increased from 12GHz to 24GHz under reverse bias voltage of 3V.4. The dual-junction PIN RCE photodetector with improved electrode was successfully prepared, in addition, the testing of the device’s quantum efficiency and high-speed response was carried out. The results showed a 70% quantum efficiency and a 4GHz 3dB bandwith.