Integrated VCSOA And PIN With High Sensitivity

Photodetector is one of the important devices of fiber communication systems.As the optical communication systems are rapidly growing towards higher transmission rate and channel capacity,the need for high speed and high sensitivity detectors is increasing.Conventional optical receiver typically use PIN or APD as the front-end photodetector.However,either device has its own limitation.The role of PIN is to convert photons to electrons,although its bandwidth is sufficient,it usually suffers from a low sensitivity due to the lacking of gain.On the contrary,APD has the required gain for sufficient sensitivity,its bandwidth is always limited,because the amplification process is carried out in electronic domain.An attractive solution to this problem is the integration of a PIN and a semiconductor optical amplifier(SOA).In this scheme,the signal is amplified in optical domain before it is converted into electronic domain.The devices of such design ensures the sufficient gain,and the bandwidth characteristics of it can be better as well.However,the combination of a surface incident PIN and an edge-emitting SOA needs hybrid integration or co-package,which consequently brings in reliability concerns and cost-ineffective issues.To solve the above contradiction,an integrated vertical cavity semiconductor optical amplifier(VCSOA)and PIN photodetector was proposed in attempting to raise the sensitivity in high speed fiber-optic communication systems.Two slightly different structures have been studied under this configuration,which are called the cascade structure and the resonance structure,respectively.To study the common and difference characteristics,the following aspects of the research work have been finished:(1)An introduction of the main parts of the devices(VCSOA,PIN photodiode,DBR grating),including their usual structures and basic theories.(2)Building of the one-dimensional numerical model for the optical transmission and amplification process in VCSOA and for the photoelectric conversion process in PIN.Modulation and optimization for each structural devices on basis of the models.(3)Establishment of the low-speed and high-speed test platforms.Fabrication and testing of two structural devices.Discussion and analysis of the testing results.