Research Of High Precision Delay Measurement Technology Of Silicon Integrated Optical Waveguides

The optical vector network analysis method based on the optical single sideband can be widely used in amplitude and delay response measurements of optical devices due to its high measurement accuracy.However,there are few reports on integrated photonic chips measurements with this technology,as large chip insertion loss,light source wavelength drift,system signal-to-noise ratio and other factors will induce large measurement errors and even wrong results.Therefore,it is very important to study the chip-level optical vector network analysis technology.In this article,the optical vector network measurement model was built and the corresponding automated measurement system was set up,which integrates instrument control,data processing,and real-time display based on Lab View.By studying the effects of signal-to-noise ratio,frequency sweep range,number of sweep points,and data processing methods on the stability of delay measurement,the measurement system was optimized to achieve high precision and stable delay measurement.And 7bits silicon-based optical switchable delay line waveguide was measured by using the designed automatic measurement system based on Lab View,in which automatic delay path switching and measurement are involved,which greatly improves the measurement efficiency.And a high-precision delay measurement with deviation of no more than 0.1ps was realized.On the other hand,for the dealy measurement of low-loss silicon nitride micro-ring resonator,the laser wavelength drift in the measurement system has a great impact on the measurement stability.By optimizing the measurement system and data processing method,a high-resolution measurement was achieved with delay and extinction ratio resolution of 10 ps and 0.04 d B,respectively.Finally,in order to reduce the bandwidth requirements of the photodetector,an optical device amplitude response measurement system based on “cascaded phase modulator-device-intensity modulator” was proposed.Based on microwave photonic frequency down-conversion and frequency scanning,the amplitude response of the optical device can be down converted to low microwave frequency domain,which can be detected with a fixed low-frequency.Compared with the measurement scheme based on the microwave photonic frequency down conversion with parallel structure,the proposed cascade structure is simpler and with lower loss.The effectiveness of the measurement system was verified by the amplitude response measurement of silicon nitride micro-ring and micro-disk.