Research On Key Technology Of Polarization Shift Keying Communication System

Optical polarization shift keying is a technology to expand the bandwidth of fiber channel.It can also be applied to all-optical signal processing.Its symbol has the characteristics of strong information expansibility,high channel utilization and good confidentiality.In the contemporary,efforts to tap the bandwidth resources,the pursuit of greater use of fiber efficiency of the contemporary,light polarization coding communication technology research has become the main dimensions multiplexing and symbol coding.Under the support of the National Natural Science Foundation of China,this paper has carried out in-depth research on some key problems in the transmitter,transmission channel and receiver of light polarization coded communication systems.Based on orthogonal polarization modulation,a bipolar optical coding scheme and the bipolar sequence multiplier are used to describe the optical fiber device.The effect of environmental stress on the output SOP of the communication system is discussed under the extreme situation of PMF and SMF.The difference receiver of arbitrary polarization state improved the performance of system.The proposed new PolSK OCDM system is verified experimentally.The main work of this dissertation is:1,The principle of polarization modulation is analyzed and verified experimentally.The key parameters of polarization modulation are analyzed by Stokes vector,and the modulation of arbitrary linear polarization and arbitrary elliptically polarized state is realized by amplitude modulation and phase modulation.In this paper,the specific method of adjusting the polarization main state is introduced in detail.The polarization modulation experiment of electronically controlled SOA,optical control SOA and electronically controlled LiNb03 phase modulator is carried out,and the polarization modulation is demonstrated in three ways.2,The effects analysis of the external environment and optical fiber transmission medium on the polarization state are carried out.The birefringence fiber is analyed with the quadratic refractive index.The theoretical model is used to calculate the internal stress birefringence and the additional external stress birefringence and calculate the length and birefringence axis of the fiber.Then the stress magnitude change and the stress direction change are obtained.The effect of local stress size and direction on the output of polarization is verified by PMF experiment with inherent birefringence.The experimental results of PMF are deduced to the applicable stress range of SMF,which is very helpful for the design of servo correction system with stable polarization output.3,The polarization state encoded and decoded by bipolar codes to vertical orthogonal polarization is completed.The orthorgnal polarization states of the receiving system demodulates the orthogonal two optical signals with a single polarization beam splitter.Any polarization state receiving system,with 1x4 splitter,through the polarization controller adjustment,get four corresponding Stokes vector light intensity,which arbitary polarization state is solved.Based on the arbitrary polarization receiving system,a differential polarization receiving system is proposed.4,The orthogonal linear polarization state and the polarization transmission matrix are abstracted as input variables in the multiplication operation.Derived from the input and output polarization state,bipolar codes are corresponding to the Miller matrixes.And controlling the current of the SOA to rotate polarization,the bipolar code multiplication is described by vertical orthogonal polarization.5,The polarization coding optical communication system is demonstrated based on the code division multiplier.while the bipolar multiplier is implemented on optical signal processing,the encoder of the optical code division multiple access system is implemented with a similar structure,and the orthogonal polarization state is encoded as a bipolar user code.In the decoder part of the code division multiple access system,the optical correlator uses the same bipolar multiplier structure,the integrator uses the low-pass filter instead,finally the polarization coding optical communication system is demonstrated.Innovations of this paper are:1,A new way is proposed for bipolar all-optical signal processing.In the vertical orthogonal polarization state,"+1" and "-1" are proposed as the bipolar code,and the bipolar coding method of optical signal processing based on orthogonal polarization is proposed.The orthogonal linear polarization state and the polarization transfer matrix are abstracted into the input variables in the multiplication operation,and the Miller matrix M(+1)and M(-1)corresponding to the bipolar code is derived from the input and output polarization states.And through the current control of the SOA polarization rotation effect,a vertical orthogonal polarization description of the bipolar code multiplication is demonstrated.2,The orthogonal polarization keying modulation mechanism is introduced into the non-coherent time domain OCDM codec system,and a new OCDM codec system is proposed,which expands the OCDM codec mechanism.3,Based on the bipolar multiplier with orthogonal polarization modulation,the multiplication of two bipolar sequences is realized,and the codecs of polarization keyed optical code division multiplexing are demonstrated.In the decoder part,the local address code and the signal synchronization problem is solved,while the original user data modulation waveform recovery is demonstrated with low-pass filter instead of integrator.4,The quaternion is introduced to simplify the environmental impact analysis while taking into account the fiber along the birefringence and external stress birefringence.The influence of the size and direction of the fiber on the polarization state of the transmitted signal is obtained,which is helpful for the design of the servo correction system with stable polarization output.5,A differential polarization receiver structure is proposed,which could greatly reduce the asymmetric distribution of polarization modulation and demodulation by the impact of the environment.