| In recent years,microwave photonics technology has developed rapidly,and it is widely used in radar,satellite communications,broadband networks,and sensing technologies.Compared with the microwave technology of the electric domain,it breaks through the technical bottleneck in the electric domain,and has the advantages of large bandwidth,low loss,andanti-electromagnetic interference.In this paper,a microwave photonic phase shifter based on polarization rmodulator(PolM)and a multi-function microwave signal processor based on dual-polarization dual parallel Mach-Zehnder modulator(DP-DPMZM)are proposed.This article consists of the following parts:(1)In this paper,we first proposed a microwave photonic phase shifter based on PolM and polarization-sensitive optical phase modulator(PS-PM)that can achieve 360° phase shift.In the scheme,an optical polarization modulator is used to generate a single sideband optical microwave signal with two orthogonally polarized tones,then a polarization sensitive electro-optical phase modulator is used to introduce the relative phase shifts between the two orthogonally polarized tones to realize the desired phase shift for the microwave signal in the photocurrent,and the microwave phase shift increases linearly with the DC driving voltage,while it keeps a constant amplitude.The simulation results show that continuous phase shift with tuning range from-1800°to+180° is realized for the microwave with the frequency from 4 to 26 GHz.(2)Second,we proposed a microwave photonic phase shifter based on cascading PolM to generate orthogonally polarized single-sideband signals.In this system,two polarization modulators are cascaded to generate a single sideband microwave signal with orthogonal polarization,and a polarization sensitive electro-optical phase modulator(PS-PM)is used for this single sideband.The signal is phase modulated to introduce a desired phase shift.Theoretical derivation and simulation show that 360°phase shift can be realized completely,and the phase shift response is linear with the DC bias voltage.The relationship between the±1 order sideband suppression ratio,the DC bias voltage of the PolM and the output phase difference of the 90° hybrid coupler is simulated.The results show that when the DC bias voltage of PolM is 0.31V and the output phase difference of the 90° hybrid coupler is 0°,the ±1 order sideband suppression ratio is maximized to 21 dB,and single-sideband modulation of orthogonal polarization can be realized.(3)Third,we proposed a frequency-doubled microwave photon phase shifter based on DP-DPMZM and PolM.A frequency doubled microwave photonic phase shifter(MPPS)without optical filter is proposed.The MPPS is based on an integrated dual-polarization dual-parallel Mach-Zehnder modulator(DP-DPMZM)and a polarization modulator(PolM).TheDP-DPMZM with a 90°polarization rotator in one arim is used to generate an optical carrier suppressed double sideband(OCS-DSB)signal with orthogonal polarization,and the PolM with two modes opposite phase modulation is used to introduce the optical phase shift between the two orthogonally polarized tones.The MPPS can realize a continuously tunable phase shift of 3600°with only one DC bias voltage,and is not sensitive to the optical carrier wavelengthand microwave signal fr-equency since no optical filter is used.We proposed a microwave photon phase shifter that can realize frequency conversion based on the above discussion.The DP-DPMZM driven by the LO and RP/IF signals is used for optical carrier suppressedsingle sideband(OCS-SSB)Jmodulation,and the PolM driven by DC bias voltage is used for phase modulation.The MWPPS can realize a continuously tunable phase shift of 360° with only one DC bias voltage,and is not sensitive to the optical carrier wavelength since no optical filter is used.The simulation results show that the frequency conversion bandwidth is 50MHz-500MHz for IF signal and 2GHz-48GHz for RF signal.The system can realize 360°phase shift while frequency conversion. |
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