Study Of Coherent Photo Receiver Measurement Method Upgrade

At present,fiber communication system for mainstream applications is non-coherent intensity modulation direct detection system.As requirement of fiber communication bandwidth increasing rapidly,people realize that traditional intensity modulation direct detection system can't meet the bandwidth requirement in the future.It is widely believed in global that coherent detection technology will be the key to next-generation fiber-optic communications.Many laboratories and device manufactures have increased research on coherent detection technology.The coherent detection receiver system has a more sophisticated structure than the traditional intensity modulation direct detection receiver system.We need about hundreds of parameter to character a common receiver.As the development of the coherent detection technology,we also put forward new requirements for the test system.Coherent detection receiver measurement system gradually become the research focus and hot pot in the field of optical fiber communication.New test system and test methods continue to emerge.The thesis studies the upgrade of the fiber optic communication coherent receiver test system.In the thesis,I introduce 3 coherent receiver test system.(1)Frequency responsivity is one important and difficult test parameter.We main use vector network analyzer to measure frequency responsivity in early stage.The most famous system is Lightwave Component Analysis developed by Agilent.This system include one network analyzer,one standard optical receiver and one reference laser source.During frequency responsivity measurement,we need to overcome the issue of the amplitude changing after the modulated signal passes coherent detection.(2)As the coherent detection communication rate increases,Lightwave Component Analysis test bandwidth can meet the new production test requirement.We start to use Optical Modulation Analysis to test frequency responsivity.The system uses the heterodyne method to generate modulation signal,collect signals with a high sample rate oscilloscope.The system test bandwidth is upon 70 GHz.(3)We need to use both local laser and signal laser during frequency responsivity measurement for abovementioned two test system.As the development of the coherent detection technology,new production included local laser come out.For this kind of production,we develop one new test system.The system almost coverage all test parameter.We measure polarization dependent loss by Mueller matrix.It also handles the polarization state very well during measure photodetector responsivity.The system also use heterodyne method to generate modulated signal for frequency responsivity test.