Study On Silicon-Based Waveguide Integrated Magneto-Optical Nonreciprocal Devices

Optical nonreciprocal devices are important components in photonic integrated circuits.Thanks to the development of the silicon heterogeneous integration technology for magneto-optical thin films using wafer bonding and direct deposition,silicon-based waveguide integrated magneto-optical nonreciprocal devices have made large development in the past decade.Among them,silicon integrated magneto-optical isolators and circulators have made significant progress in key performance in terms of isolation ratio and insertion loss.New devices such as nonreciprocal magneto-optical switches,magnetic field sensors,magneto-optical modulators,and quantum nonreciprocal photonic devices are also rapidly emerging.However,the insertion loss of silicon integrated magneto-optical isolators and circulators is as high as more than 5 dB,which is significantly higher than that of discrete devices,and the isolation bandwidth of silicon integrated magneto-optical isolators is only 8 nm,which is far from meeting the device requirements of tens of nanometers in wavelength division multiplexing scenarios.At the same time,the functions of magneto-optical nonreciprocal devices are relatively simple,and the development of new functions based on nonreciprocal photonic devices,such as nonreciprocal optical routing,and magneto-optical phase shifter,still needs to be further explored.In terms of device fabrication,the silicon integration process of magneto-optical nonreciprocal devices with high tolerance and compatibility with CMOS back-end process still needs to be further studied.In this dissertation,the problems of high insertion loss,narrow isolation bandwidth and single function of silicon integrated magneto-optical nonreciprocal devices are systematically studied.We have designed and fabricated silicon-on-insulator(SOI)-based,silicon-nitride-based low-loss magneto-optical isolators and circulators,developed ultrabroadband silicon-nitride-based magneto-optical isolators and circulators,and developed the applications of nonreciprocal devices in laser-isolator coupling modules,integrated collinear laser detection modules,magneto-optical nonreciprocal optical routing and high-speed magneto-optical phase shifters.Firstly,based on the theory of magneto-optical waveguides,low-loss magnetooptical waveguides are designed.Monolithically integrated silicon nitride-based magneto-optical nonreciprocal devices were developed based on the standard silicon photonics process and magneto-optical thin film deposition method.Broadband magnetooptical isolators and circulators under TM/TE polarizations with high isolation of 32 dB,low crosstalk of-32 dB,and low insertion loss of 2.3 dB were demonstrated on the silicon nitride waveguide platform.Narrow-band optical isolators based on silicon nitride microring resonators achieved low insertion loss as low as 0.5 dB.At the same time,the devices showed good temperature stability.Secondly,an ultra-wideband magneto-optical isolator was proposed and fabricated.Based on the principle of dispersion compensation,the dispersion of silicon nitride waveguide and magneto-optical material are compensated by each other,and ultrawideband magneto-optical isolators and circulators were designed.The theoretically 30 dB isolation bandwidth exceeding 240 nm was achieved.Experimentally,ultra-wideband silicon nitride integrated magneto-optical nonreciprocal devices were fabricated based on standard silicon photonics process,with maximum isolation of 27 dB,insertion loss of2.9 dB,and 20 dB isolation bandwidth of 90 nm,which was more than an order of magnitude higher than that of similar devices.At the same time,the dissertation systematically analyzed the fabrication tolerances of materials and devices.Finally,a series of integrated optical modules based on silicon integrated magnetooptical nonreciprocal devices were developed to expand the application of the devices.Based on the fabricated unit silicon integrated magneto-optical devices,the coupling packaging module of the laser and the isolator was experimentally realized,and the edge mode suppression function after the coupling of the isolator to the laser was experimentally verified.The integrated collinear laser detection module based on the integrated magneto-optical circulator was developed,and the synchronous transceiving function of the module with the same caliber was tested.A nonreciprocal optical router based on the magneto-optical phase shifts was developed,to realize on-chip nonreciprocal optical transmissions between 5×5 ports.A high-speed magneto-optical phase shifter based on on-chip electromagnet was fabricated,and a silicon integrated magneto-optical phased array module was further studied,realizing high-speed beam scanning based on magneto-optical phase shifts.