DPSK Self-Homodying Coherent Detection System Based On Optical Pre-amplifier

The self-homodying coherent detection in space laser communication adopts more advanced device of optical fiber communication network,which enables the receiver have simple structure and its detection sensitivity to be slightly below the homodyne detection.Therefore,it has great potential in the future satellite communication field.In this paper,DPSK self-homodying coherent detection system based on optical pre-amplifier is studied.First,the principle of the system is introduced,different modulation modes are analyzed and then simulation software is used to compare these modulation modes.With added the preamplifier,the sensitivity of the receiver is improved greatly,BER and SNR of system are discussed.Second,it compares the traditional delay interferometer with the dual core interferometer,mainly studies the selection of delay line when the rate of system is changing and simulates the delay mismatch caused by temperature.Extensive research on the filtering effect of different optical filters is conducted and optimal bandwidth of the filter is obtained by simulation.In addition,we take into account of the practical application of the system.The Doppler frequency shift of the system is calculated,by selecting the bandwidth of filter reasonably can reduce the influence of Doppler frequency shift.And the coupling efficiency of the optical signal to the single-mode fiber under different condition is also studied.Finally,we establish the experiment platform of optical pre-amplifier DPSK self-homodying coherent detection system verify that the optical signal can be successfully demodulated when the requirements of bit error rate and the receiving sensitivity are met.