High-precision silicon-based integrated optical temperature sensor

Traditional temperature detection has certain limitations in terms of sensing accuracy and response time. Chip-level photoelectric sensors based on the thermo-optic effect recently aroused widespread interest not only because they can improve measurement sensitivity and speed, but also because they can help reduce system complexity and cost. State-of-art integrated optical temperature sensors mostly measure the optical interference of broadband light sources or tunable light sources in the micro-resonators to provide accurate and fast measurement solutions. However, these solutions based on wide-spectrum detection cannot achieve real-time processing, are costly with complicated signal post-processing, and are difficult to implement in highly integrated systems. To solve the above problems, we show a fast and high-precision temperature measurement method using a silicon-based integrated micro-ring array. The different responses of the cascaded micro-ring array are measured by a single-frequency laser at different temperatures. The results are utilized to model the relationship between the electrical response of the detector array and the real temperature, thereby realizing real-time high-precision temperature measurement. In addition, to enlarge the temperature detection range under a fixed-wavelength light source, a cascaded micro-ring structure is adopted. Based on the proposed structure, a silicon-based integrated temperature sensing system including a light source, a micro-ring array, a detector array, a signal post-processing unit and an output data unit is designed. Depending on the requirement of actual applications, the system can change the temperature measurement range and resolution by separately designing the number of cascaded micro-rings, the center resonance wavelength, and the half-width of the resonance peak while ensuring low system power consumption and cost. Through the optimized design of the micro-ring array, a temperature sensor with a response range covering −20~105°C, accuracy better than 60 mK, and a response time as quick as 20 μs is demonstrated.