Large-scale Optical Switch Based On Silicon Photonics

With the rapid growth of communication traffic,the development speed of datacenters is gradually lagging behind the growth of demand,and its power consumption is approaching the thermal limit(～300 W)of current integrated electronic circuit cooling technology.As a result,the performance improvement of electrical chips has gradually slowed down.As the core device in datacenters,electrical switches are gradually unable to meet the needs of contemporary datacenters.Optical switching technology has the advantages of high capacity,low latency,and low power consumption,which fits the demand of the current datacenters for a new generation of switching technology.And silicon-based integrated optoelectronic devices have the advantages of small size,low power consumption,and compatibility with CMOS processes,which have been extensively studied in recent years.This thesis mainly studies large-scale optical switch array technology.In view of the challenge faced by the development of large-scale optical switch array,the switch cells are studied and the 128-port Benes network thermo-optical switch array chip working in the O band is researched and fabricated.Specifically,the main research progress made in this thesis has the following two points:1.We researched and designed a silicon-based 2×2 thermo-optical switch cell with low loss and large bandwidth,the loss of a single switch cell is～0.25dB,and～-28dB crosstalk at 1310nm wavelength,measured lower than-20dB crosstalk at a 40nm range.Compared to the most advancing demonstration at present(insertion loss is～0.13dB,-20dB crosstalk is only about 14nm bandwidth),we achieved a larger working bandwidth after sacrificing part of the loss.According to the demand for high-speed(ns-level switching speed)response of the switch array,a silicon-based 2×2 electro-optical switch cell with high-speed and large bandwidth was researched and fabricated.The loss of a switch cell is～1.1dB,and～-28dB crosstalk at 1318nm wavelength,measured lower than-25dB crosstalk under 30nm range,which has a wider bandwidth than the most advancing demonstration in this area(insertion loss is～0.8dB,-25dB crosstalk is only about10nm bandwidth)without the adjustable optical attenuator(VOA)or cascade structure so far.2.The analysis method and fabrication of the large-scale switch array are studied.Specfically,a 128-port Benes network silicon-based thermo-optical switch array chip is fabricated,which now is the largest reconfigurable non-blocking network switch array.The footprint of the chip is～16.2×16mm~2 with a total number of 1690 electrical pins,which results in that the electrical packaging of the chip will be difficult.In this thesis,a silicon adapter board was designed and fabricated,which solves the fan-out problem of the high-density electrical pins on the optical chip.At the same time,the print circuit board(PCB)of the driver circuit was designed and manufactured,after realizing the design of the upper computer program,we successfully tested a single circuit module(96 channels),which can be combined to control the switch array chip with thousands of electrical ports.It provides a feasible solution for the drive control problem of large-scale optical switch arrays.