Research Of A Novel Dual-Absorption Layer Photodector For Optical Communication System

The rapid progress of large capacity, long-haul WDM optical fiber communication system raises higher requirements for optoelectronic devices used in WDM systems. The optoelectronic devices must continuously updated to cope with the high performance needed for future optical transmission systems. The photodector is the key devices in the optical fiber communication system, and some new devices were fabricated. PIN photodetectors are widely applied to the optical fiber communication systems. The junction capacitance is an important factor affecting bandwidth and have a great impact on response bandwidth. We adopt side etching proceoss to reduce junction area of the dual-absorption layer photodetector is and get a novel dual-absorption layer photodetector. The device reduce junction capacitance and have high quantum efficiency because of dual-absorption layer.This dissertation focuses on the novel dual-absorption photodector and mainly researches their high performance on quantum efficiency and response bandwidth. The main research work and innovations include the followings.1. We researched capacitance characteristics of the PIN photodector and dual-absorption layer photodetector. The absorption layer thickness is200nm,400nm,600nm,800nm and1000nm,and the capacitance ratio of PIN and PINIP reduces with the increasing of the absorption layer thickness.2. The theoretical results show the devices have the maximum bandwidth with600nm absorption layer thickness. A novel photodetector was proposed and the quantum efficiency can reach93%for600nm absorption layer thickness. The response bandwidth achieves26GHz, and can achieve an improvement of44%over16μm absorption layer diameter PINIP photodetector when diameter is located at5μm.3. The novel dual-absorptionlayer photodetectors of the upper and lower absorption layer with different diameters have been studied. We assume upper absorption layer on a constant diameter of5μm. when the under absorption layer3μm,5μm,10μm and16μm in diameter, the results after the simulation show the response bandwidth is29GHz,26GHz,24GHz and22GHz. The total bandwidth increases with the increasing of the absorption layer thickness.4. The novel dual-absorptionlayer photodetector of the upper and lower absorbent layers with different thickness has been studied.For the upper and lower absorption layer with the diameter of5μm, the thickness of the upper absorption layer is positioned600nm,while that of the under absorption layer is800nm,600nm,500nm and300nm. The results show the photodetector response bandwidth is24GHz,26GHz,21GHz and18GHz, respectively. The devices have the maximum bandwidth with600nm absorption layer thickness.5. The PIN photodetector and the mushroom photodector has been fabricated. The response bandwidth of PIN photodetector is6.8GHz, while that of mushroom photodector is9GHz. The absorption layer of photodetector is adopted side etching process to junction area, and it increases the response bandwidth.