Research On Wavelength Locking Of Silicon-based Microring Resonator

In recent years,with the continuous increase of network traffic,the traditional communication is gradually difficult to meet the needs of people.Silicon optical technology has the advantages of large bandwidth,low delay,low loss and so on.It has been widely used in optical Internet,optical computing and other fields,and has attracted more and more attention.Silicon-based microring resonator is an important device in silicon optical technology.It has the advantages of wavelength selection and compact structure.It is compatible with CMOS technology and has important applications in optical interconnection networks.However,due to manufacturing errors and the interference caused by temperature drift,the working performance of the microring resonator is affected,so it is necessary to lock the wavelength of microring resonator.The main research work of this paper includes the following two parts:1.An offset resonance locking method based on a single microring resonator is proposed.The thermotuned voltage is applied to the integrated heater of phase shifter,and the relationship between the thermotuned voltage and the introduced phase is analyzed.The dithering signal is loaded to the microring resonator and the error signal about the working state of the microring resonator is extracted by coherent detection method.The influence of square wave and cosine wave as dithering signals on the extraction error signal is studied experimentally.It is proved that the feedback signal can be immune to the change of input optical power by using the method of division.Based on the relationship between the feedback signal and the microring resonator,the wavelength offset locking system is designed to achieve the wavelength offsets of-0.048 nm,0 and 0.061 nm.2.A locking method based on cascaded second-order microring resonator is proposed.The coherent detection method is used to load two dithering signals of different frequencies into two microrings.The two error signals extracted have opposite monotonicity.In the locked interval,the error signals change the fastest and have only one intersection point.According to this characteristic,the locking point search algorithm is designed and the locking of the cascaded second-order microring resonator is realized.Before and after locking,the output spectrum 3dB bandwidth,insertion loss,extinction ratio and in-band fluctuation of the microring resonator drop port were improved.