Silicon-based Thermo-optic Tunable Integrated Chips And Their Applications

With the development of society and economy,people’s dependence on cars is getting higher and higher.However,the car environment is closed,the space is small,and many kinds of harmful substances are easy to accumulate,which seriously threatens people’s health.At the same time,in order to meet people’s higher comfort requirements for automobiles,more and more new materials and new processes are used in the manufacture of automobile seat cushions,dashboards,plastic parts,blankets and other components.The use of these materials can easily volatilize harmful gases such as stupid,toluene,formaldehyde,styrene,and acetaldehyde in the car,posing a threat to the safety of passengers.Therefore,it is of great research significance to develop a portable system that can monitor the air quality in the car in real time.For the spectral detection method commonly used in gas detection,considering the shortcomings of traditional spectrometers such as bulky,complex equipment and high price,we focus on the development of chip-scale spectrometers.We propose an ultra-high-resolution spectrometer chip based on the Eulerian micro ring resonator,which includes 4 input ports,12 output ports,one Eulerian micro ring resonator,10racetrack-type cascaded micro rings,and metal heating electrode.The entire filtering process of the spectrometer chip includes ultra-precision filtering and coarse filtering.For ultra-precision filtering,we designed an Euler micro ring resonator.We introduced a wide waveguide structure,which can greatly reduce the waveguide loss and improve the resolution of the spectrometer.At the same time,in order to avoid the excitation of high-order modes,the micro ring is designed to be based on the shape of the modified Euler curve.By optimizing the maximum curvature radius R_max and the minimum curvature radius R_min,the mode mismatch loss can be effectively avoided,and the orientation of the micro ring can be adjusted.The coupling region is set as an S-shaped curved waveguide,which is also beneficial to improve the coupling efficiency and increase the resolution of the spectrometer.For the coarse filter,we designed 10 racetrack-type cascaded micro-ring structures,thereby constructing a 10-channel coarse filter.After the simulation design,the spectrometer can achieve 4pm spectral resolution in the working band of 14nm.After the chip is manufactured and our test,the spectrometer chip can reconstruct single-peak and double-peak spectral lines within the working range of 10nm,and the resolution reached 5pm.We propose a computational spectrometer chip based on a single micro ring resonator,which includes a single micro ring structure,input/output grating couplers,and metal heater electrodes.According to the relevant theory of compressed sensing,using the thermo-optical tuning characteristics of the micro ring,a measurement matrix A is constructed including the information of heating power and the wavelength point.This matrix A is fixed.In actual use,the spectrometer only needs to capture the measurement value Y,and we use the measurement matrix A and the reconstruction algorithm based on convex optimization to restore the spectral information to be measured.We simulated the working feasibility of the whole system and analyzed some parameters that affect the reconstruction effect.Finally,a test system is built to verify the spectrometer chip’s restoration of single-peak input at a working bandwidth of 50 nm,and the resolution of double-peak restoration is 0.04 nm.At last,we summarize the full text and make an outlook on the future research work of chip-scale spectrometers.