Design Of Drive And Control Circuit For SOI Thermo-optic Switch Array

In recent years,the data flow of network transmission is exploding.Traditional electrical switching is difficult to meet the development needs of network broadband,and it is urgent to accelerate the application research of optical switching.Optical switch array chips and modules,as the core components in optical switching systems,are of great significance to the development of optical communication technology.Thermo-optic switch technology based on Silicon on Insulator(SOI),with its advantages of fast response,low loss,low power consumption,high integration,and compatibility with COMS process,it is playing an active role in the development of optical networks.In addition to continuously improve the performance of the SOI thermo-optic switch array chip itself in design,attention should also be paid to the impact of the large-scale switch array drive and control circuit on the comprehensive performance of the switch module.In this paper,based on the research of the structure of the thermo-optic switch array and its working mechanism,the packaging of the SOI thermo-optic switch array chip developed by the laboratory is completed.For the single-channel cascaded optical switch on the chip,a control circuit with a single-chip microcomputer as the core and a drive circuit with the driving chip ULN2803 as the core are designed and implemented to realize independent control of multiple optical switch units.On this basis,the number of output ports of the drive circuit is expanded,and a multi-channel drive control circuit with the upper computer as the control end is designed and manufactured.Based on the drive and control circuit,a static parameter test system and a dynamic response test system of the optical switch are built.The insertion loss,switching voltage,crosstalk and response time of the optical switch were tested.The experimental results show that the rise time of the square wave signal output by the drive circuit is 334ns and the fall time is 160ns;the response rise time of the optical switch is 4us and the fall time is 6us.The driving circuit can quickly drive the SOI thermo-optic switch,and its output voltage can be adjusted in a wide range,which can be applied to thermo-optic switches with different switching voltages.Silicon material has a great thermo-optic coefficient(1.86×10^-4K^-1).The change of the ambient temperature and the temperature of the chip itself will affect the performance of the optical switch.Therefore,this paper designs and manufactures a chip temperature control system based on single chip microcomputer and semiconductor cooling chip.The real-time temperature of the chip is detected by the DS18B20 temperature sensor,and the temperature value will be displayed on the LCD after being input into the microcontroller.After comparing with the set temperature value,the output of the single chip computer controls the LMD18200 and drives the TEC to heat or cool to maintain the constant temperature of the chip,which further improves the efficiency and stability of the SOI thermo-optic switch array.