| Compared to electrons as information carriers,photons do not interfere with each other,and different light waves can achieve multi-channel communication at the same time.Therefore,photons have larger bandwidth,faster speed,and higher communication capacity.In addition,photons have more multiplexing dimensions,such as phase,wavelength,mode,and polarization,provide variously flexible operating spaces for photon information coding and transmit information more efficiently and accurately.In the photonic integrated circuits（PIC）devices of different material systems,silicon-based PIC photonic devices not only inherit the high integration of microelectronic devices,but also can be compatible with CMOS technology,so as to integrate photonic devices with different functions on the same substrate to form a multi-functional photonic chip,which is an important research direction of optical integration.The low cost,small size and compatibility with CMOS technology of functional silicon-based microring resonator devices provide a feasible solution for achieving high-performance systems on chip.This paper adopts silicon-based microring structure,and conducts theoretical and experimental research on its applications in optical sensing,optical logic calculating,optical switching,and optical multiplexing.The specific works are as follows:1.The research significance of photonic integrated devices and on-chip optical chips is introduced.The existing problems of silicon-based microring photonic integrated devices are analyzed by introducing variously typical silicon microring functional devices and recent research progress in related fields.The basic principle and main performance parameters of microring resonators are introduced.The principles of optical sensors,optical logic gates,optical switches,and optical multiplexers based on silicon microring resonators are discussed and analyzed.2.Microring resonator with small size and high Q factor provides a good performance foundation for specific applications.The influence of concentric rings bidirectional mutual coupling coefficient and waveguide-microring bidirectional mutual coupling coefficient on the splitting state of resonant peaks and the symmetry of splitting resonant peaks are analyzed by the coupling mode theory.Based on theoretical calculation and simulation analysis,the design method of high Q-factor dual microring resonators was verified by using 300 nm CMOS technology.The highest Q factors of dual concentric mircoring and racetrack resonator with outer-ring radius of 5μm are measured to be～9.00×104 and～7.32×104 respectively,and the corresponding resonant wavelengths are 1530.783 nm and 1536.596 nm respectively,and the extinction ratio is greater than 20 d B.Compared to silicon-based microring resonators with the same radius,the Q factor is improved.3.A high refractive index optical sensor based on light intensity detection is proposed using the influence of mutual coupling of concentric microrings on resonance.The effects of different microring structures and the position of the object to be measured on the sensor performance were analyzed.The theoretical calculation results show that for an all-pass microring or a through/drop microring,the sensor has a high light intensity sensitivity when analyte is applied between the inner and outer rings,and the best light intensity sensitivity is calculated to be 1813.95 d B/RIU.4.According to the silicon-based concentric microring structure,a logic gate cell is designed.Through the effect between pump light and signal light defined in this paper,the output port presents a logic state opposite to the signal light,thereby realizing the"NOT"gate logic function.Signal light with wavelength of 1558.1 nm,this"NOT"gate achieves an extinction ratio of 15.5 d B.Using the cell device,logical"NAND"is realized based on two"NOT"gate cells and a Y branch.According to diverse demands,the logic cell can be expanded into composite logic gates with different functions to achieve high integration of on-chip optical logic devices.5.Optical switch is an important functional element to control the on-off of the optical path and change the optical transmission path.An optical switch based on Ge2Sb2Se4Te1（GSST）-assisted silicon-based racetrack microring is designed.The device structure parameters are designed and optimized by the time-domain finite-difference method.By adjusting the crystalline and amorphous states of GSST,the switching ON and OFF states can be achieved.With an active region of only 30μm×55μm,the device exhibits an extinction ratio of～18 d B at resonant wavelength,3-d B bandwidth of 1 nm,and an insertion loss of less than 1 d B in both the switching ON and OFF states.Due to the nonvolatile characteristic of GSST,it is not necessary to continuously power up or heat up to maintain the switching state.Therefore,the on-chip N×N switch matrix based on the proposed switching cell has good application potential in high integration,low power consumption,nonvolatile,and so on.6.A high-order mode optical switch based on GSST-assisted silicon-based microring is proposed.The composite structure composed of GSST and multimode waveguide microrings can achieve TE0,TE1,and TE2 mode switching functions when the input is a fundamental mode or a higher-order mode.The theoretical calculation results show that with the increment of the mode order number,the extinction ratio of the Cross port decreases,the loss and mode crosstalk at the resonant wavelength of the Through port increase,but the multiple modes supported by the waveguide exhibit good response performance.This design can avoid the previous step of converting higher-order modes to fundamental modes before performing signal processing,reducing signal processing time,effectively improving signal processing speed,and providing a possible solution for fast on-chip optical signal transmission and processing.7.Hybrid multi-dimensional（de）multiplexers can realize multi-channel and high- capacity data transmission.In this paper,based on the directional coupling structure,TE and TM polarization beam splitters have been designed and fabricated,based on the microring resonator,wavelength-mode multiplexer/demultiplexer was designed and fabricated.The design was theoretically calculated and simulated using finite difference time domain method,and a 180 nm silicon CMOS technology was used for tape-out fabrication.Due to limitations on the polarization sensitivity of vertically coupled gratings,the tape-out results of the multiplexer/demultiplexer operating under TM and TE polarization were tested and analyzed respectively,demonstrating the feasibility of the proposed hybrid multi-dimensional（de）multiplexer.Due to the small size of the microring,it can be expanded into a highly integrated,multi-channel photonic communication system based on demand,providing a solution for high-capacity on-chip optical calculating and optical transmission. |
