Experiment And Simulation Analysis Of Silicon Mach–Zehnder Thermo-optic Switch With Trench

Since the 20 th century,electrical interconnections have been limited in key performance such as transmission bandwidth,signal delay,and power consumption.Optical interconnection replaces electrical interconnection with its higher performance.Silicon photonic devices are compatible with CMOS,which have low cost and high commercial potential.Among them,silicon thermo-optic switch is one of the key devices in optical networks.The silicon thermo-optic switch generally does not require a doping process step,which can achieve low device loss.The two key parameters of silicon thermo-optic switches are power consumption and response time.It is necessary to control the power consumption and response time of the switch network in a largescale on-chip integrated system.The heat transfer process in a silicon thermo-optic switch determines the power consumption and response time.This paper simulates the heat transfer process in the silicon Mach-Zehnder thermo-optic switch.When the distance between the two arms is large enough,thermal crosstalk between the arms is negligible.It is found that the influence of the upper and lower cladding thickness on the power consumption and rise time is much greater than the substrate thickness.Increasing the thickness of the lower cladding layer can reduce the power consumption by about 40%,and decreasing the thickness of the upper cladding layer can reduce the power consumption by about 20%.When designing a low power consumption thermo-optic switch,without affecting the optical mode field in the waveguide and its mechanical strength,it is necessary to reduce the thickness of the upper cladding as much as possible and select the appropriate thickness of the lower cladding.This work also design deep trenches on both sides of the thermo-optic phase shifter in the switch to reduce power consumption.The experimental results show that power consumption of the two switches without and with trenches are 28.6 m W and 18.7 m W at 1550 nm wavelength.The power consumption of switch is reduced by 34.7% due to the trenches.The extinction ratios of the cross state both exceed 36 d B.Simulation shows that when the width of the trench is greater than 2 ?m,its changes have little effect on power consumption.Different trench depth will bring about 20% to 40% reduction in power consumption.When the heating resistance and the trench spacing are less than 1.5 ?m,the power consumption can be reduced by more than 35%.It is worth noting that when the distance between the two arms of the MZI thermooptic switch is too close,the thermal crosstalk phenomenon will have a non-negligible effect on the switch performance.At the end of this paper,the influence of the thermal crosstalk on the switch performance is analyzed.A trench is designed between the two arms to suppress thermal crosstalk,and the effect of the trench on thermal crosstalk is analyzed.