The Study Of Waveguide Delay Line Based On SOI Optical Switch

Optical switch is an essential optical device in optical information system,and its function is to realize the cross-connection of optical paths and the split and bifurcation of different light paths at the nodes of optical network.Optical switch can be used in optical interconnection,optical transmission,optical routing and other systems.The optical switch based on SOI has the characteristics of compact structure,strong expansibility and high reliability,and is one of the key components to realize the reconfigurable communication of optical network on chip.Cascaded switch array provides a feasible solution for data synchronization and buffering in large capacity optical networks and ultra-high speed signal processing in radar systems.For a2×2 MZI thermo-optic switch,the 3-dB coupler contained in it directly affects the performance of the switch.The purpose of this paper is to design a high-performance 3-dB coupler and develop a low-power,low crosstalk thermo-optic switch based on different couplers.Finally,based on the high performance of thermo-optic switch,a tunable optical waveguide delay line is also developed.In this paper,based on the analysis of planar waveguide theory,coupler and the working principle of thermo-optic switch,three kinds of 3-dB coupler are designed,and their performances are compared and analyzed.Based on the existing couplers,thermo-optic switch with adiabatic coupler is designed and fabricated.The experimental results show that the 2×2thermo-optic switch with adiabatic coupler has a power consumption of 45 m W,the insertion loss and crosstalk are 11.8 dB and-23.1 dB respectively.The rise time and fall time of the optical switch are 14 ?s and 8 ?s,respectively.In the wavelength range of 1530-1570 nm,the crosstalk of the optical switch is less than-15 dB,which shows good wavelength independence.In order to further improve the crosstalk and extinction ratio of the device,a thermo-optic switch based on multimode interference coupler is also designed and fabricated.The experimental results show that the power consumption of the 2×2 thermo-optic switch based on multimode interference coupler is 41 m W,the insertion loss is 11.4 dB and the crosstalk can reach-30.1dB.the rising time and falling time of the optical switch are 12 ?s and 8 ?s.Finally,a 3-bit optical waveguide delay line based on multimode interferometer coupler thermo-optic switch is designed and fabricated successfully.The results show that the minimum delay of the delay line is 7.9 ps,and the maximum delay can reach 55.3 ps,which meets the design expectation well.In order to reduce the transmission loss and increase the delay in the optical waveguide,a 6-bit optical waveguide delay line with 1200 nm width is designed,and the expected experimental results are obtained,which lays a good foundation for integrated multi-channel beam forming and control system.