Rsesearch On Silicon Integrated Optical Phase Shifter And Microwave Photonic Phase Shifter

With the unprecedented rapid development of the optical communication and integrated circuit technology at the beginning of this century,integrated photonics has gradually received more and more attention.Silicon photonics offers many advantages,such as small footprint,low cost,high integration,and complementary metal oxide semiconductor(CMOS)compatible fabrication.Due to the large bandwidth and high speed of optical communication,silicon photonics has the potential to become the main platform for optoelectronic integrated circuits.At the same time,the rapid development of photonic integrated circuit brings the integrated microwave photonics to a new level.Integrated microwave photonics combines radio frequency(RF)engineering and integrated photonics.The generation,transmission and processing of high-speed RF signal can all be realized in photonic integrated circuit.Phase shifters are indispensable components in optical signal processing and microwave signal processing.The main research achievements of the thesis can be divided into two parts:1.A silicon photonic RF phase shifter with linear phase response and low RF power variationMicrowave photonic phase shifters are key components for optical beamforming in phased array antennas.Conventional phase shifters are limited to narrow band operations due to the nonlinear phase responses.Thus,the RF phase-shift linearity needs to be taken into account in the evaluation for the performance of phase shifters.Besides,RF power variation and phase shift range are both important factors in the design of phase shifters.To achieve a phase shifter with a linear phase response and a low RF power variation,here we propose an on-chip RF phase shifter based on a tunable silicon photonic interleaver.An interleaver is a periodic optical filter in wavelength,which is usually designed to possess flat-top passband transmission.Since ideal bandpass filters are supposed to be dispersionless,many interleavers are designed with high-linearity phase responses in the passbands.The two factors enable a linear phase shift and a low RF power variation of the phase shifter.The interleaver-based phase shifter(IBPS)is composed of an add-drop microring resonator(MRR),an interleaver,and a2 × 1 multimode interferometer(MMI).As a result,a full 360° phase shift for a 40-GHz RF photonic signal can be realized,while a linear phase shift of 188° can be achieved with a linearity of 0.08 and a <1-d B RF power variation.A tunable phase shift of 320° over an RF frequency range from20 GHz to 40 GHz was also experimentally demonstrated.2.Wideband low-power microwave photonic phase shifter by bidirectional polarization multiplexingSilicon photonic phase shifters can control the phase of optical signals and can be used in modulators,optical switches,phased arrays,and tunable optical attenuators.The realization of large-bandwidth and low-power unit devices is an important prerequisite for large-scale nanophotonic circuit.Therefore,here we propose a wideband low-power microwave photonic phase shifter based on bidirectional polarization multiplexing which are realized by two polarization splitter and rotators(PSRs)and a sagnac loop.Compared with traditional phase shifters,the phase shifter can decrease the power consumption by 4 times with a phase shift of ?.