Research On Phase-tunable Microwave Photonic Filter

Microwave photonics is a multidisciplinary interdisciplinary field combining photonics technology and microwave millimeter-wave technology.Using photonics technology to construct microwave photonics signal processing system can effectively overcome the "speed bottleneck" problem existing in traditional electronic devices.Microwave photonic filter is an important application in microwave photonics.Compared with traditional electrical filters,MPF has advantages of low loss,large bandwidth,spectrum reconfigurability,immunity to electromagnetic interference and high operating frequency.Microwave photonic phase shifter is also the main research direction of microwave photonics,which is widely used in optic-controlled phased array antenna.The phased array antenna finally realizes the emission of RF signal in a specific direction by adjusting the phase of the transmitted RF signal.When multifunctional signal processing is required,cascaded microwave photonic devices with different functions need multilevel electro-optical and optical-electro conversion,which increases the complexity of the system on the one hand and increases the power loss on the other.In order to achieve the reasonable allocation of resources,the research of microwave photonic signal processing system with multiple signal processing functions is imperative.In this paper,A phase-tunable microwave photonic filter is researched.By combining the filter technology based on broadband light source with the phase shift technology based on polarization modulation,it can not only realize the filtering function,but also realize the phase shifting function independently by tuning the bias voltage,which has the advantages of multiple functions and simple structure.In this paper,the concept of two signal processing technologies,microwave photonic filter and microwave photonic phase shift,are introduced by introducing microwave photonics.The research status of single passband microwave photonic filter and phase-tunable microwave photonic filter at home and abroad is summarized,and the main components of microwave photonic filter are introduced.The basic principle,realization method and basic parameters of microwave photonic filter and microwave photonic phase-shift technology are described in detail.A phase-tunable microwave photonic filter based on dual-polarization dual-parallel Mach-Zehnder modulator and fiber Mach-Zehnder interferometer is proposed which is analyzed and verified by Matlab simulation and experiment.The wavelength of broadband source is cut by Mach-Zehnder interferometer,and the microwave photonic filter is realized by using single mode fiber as delay element.Quadrature linearly polarized light is generated by DPol-DPMZM,and the phase shift function is realized by combining quadrature linearly polarized light with polarizar.The frequency response,tunability and filtering effect of Mach-Zehnder interferometer and single mode fiber under different parameters are systematically simulated.Through experiments,by adjusting the optical variable delay line,the tunable single passband filter with the center frequency from 0 to20 GHz can be realized.By adjusting the bias voltage on the lower arm of the modulator,the microwave signal in the passband range can be continuously shifted in the range of-180°-180° in200 MHz bandwidth.A phase-tunable microwave photonic filter based on dual-polarization dual-parallel Mach-Zehnder modulator and microfiber ring resonator is proposed which is analyzed and verified by Matlab simulation and experiment.In the case of using microfiber ring resonator instead of Mach-Zehnder modulator to cut the broadband source,a single passband filter with phase controlled by the bias voltage on the lower arm of the modulator is realized after the photoelectric detector beats.The experimental results show that the 3 d B bandwidth is 300 MHz and the rejection ratio is15 d B,and the microwave signal in the passband range can realize the continuous tuning of-180°-180° phase in the 3 d B bandwidth.