Research On Microwave Photonic Channelization Based On Polarization Modulation

Microwave photonic channelization has been widely and deeply studied because of its large-bandwidth signal processing capability,which has important application prospects in radar,electronic warfare,satellite,and other fields.Microwave photonic channelization based on dual coherent optical frequency combs makes full use of the parallel and broadband advantages of photonic technology.In view of this key challenge,this paper mainly carries out the following three aspects of research work:1.The channelization model with the microwave photonic dual-output image-reject mixing is established,and the principle of the dual-output image-reject mixing increasing the number of the output channels to 2 times of the comb line number is introduced.A model of dual-output image-reject mixing is built,and the influence of the key devices,such as the 90° optical hybrid and the 90° hybrid,on the key performance,such as the image-reject ratio and the output spectrum shape,is analyzed and verified by simulation.2.A microwave photonic channelization based on polarization division multiplexing and dual-output image-reject mixing is proposed and studied.By introducing the polarization orthogonality of the optical local oscillators and the dual-output image-reject mixing,the number of the output channels is increased to 4 times of the comb line number.The principle of the dual-polarization optical local oscillator,which improves the number of the output channels,is analyzed through the theoretical derivation and the simulation.And an experimental verification is carried out.An RF signal with the center frequency of 10 GHz and the bandwidth of 4.8 GHz is divided into 4 channels with only one RF optical carrier and one local-oscillator optical carrier in this experiment.The reject ratio of the crosstalk is higher than 23 d B in each channel.3.A microwave photonic channelization based on the double-sideband modulation and the dual-polarization optical local oscillators is proposed and studied.Through the double-sideband modulation of the signal optical frequency comb,the number of the output channels is increased to 8 times of the comb line number by combining the polarization orthogonality of the optical local oscillators.The number of the output channels is improved by the double-sideband modulation and the polarization orthogonality,the principles of which are analyzed through the theoretical derivation and the simulation.And an experimental verification is carried out.An RF signal with the center frequency of 14 GHz and the bandwidth of 9.6 GHz is successfully divided into 8 channels with only one RF optical carrier and one local-oscillator optical carrier in this experiment.Meanwhile,the channelization for two RF signals with the bandwidth of 2.4 GHz and the center frequency of24.8 GHz and 30.8 GHz is also verified by experiments.The reject ratio of the crosstalk is higher than 21 d B in each channel.