The Development Of Polymer-based Optical Switches And Delay Lines

In recent years,traditional phased array antennas have been unable to meet the increasing demands for performance due to the aperture effect and narrow bandwidth.With the development of optoelectronic technology,optical phased array antenna,with large instantaneous bandwidth,no aperture effect,low loss,small size and anti-electromagnetic interference,has attracted the attention of researchers.The critical technology of optical phased array antenna is optical true-time delay technology(OTTD).As the important device of optical true-time delay technology,optical switch and optical delay line are very interesting for researchers.Compared with the conventional optical switch and the optical time delay line,the optical switch and time delay line based on polymer waveguide have been the focus of research in recent years due to their merits,such as being easily controlled,well process tolerance,small size and easily being monolithic integrated.In addition,with the explosive growth of data in the information age,the traditional network has been unable to meet the needs of human for date transition,so to construct an all-optical network is imperative.As the basic unit of Optical Add-Drop Multiplexer(OADM)and Optical Cross-Connection(OXC)which is the core device of the all-optical network,optical switch plays a key role in the all-optical network.Therefore,polymer-based total internal reflection(TIR)thermos-optical switch and an optical delay line based on the thermos-optical switch are developed in this paper.Based on the analysis of planar waveguide theory,thermos-optical effect and working principle of total internal reflection thermos-optical switch,a low-power 2x2 total internal reflection digital thermos-optical switch is designed.The simulation results show that the power consumption of the thermos-optical switch is 42 mW,the crosstalk is-31dB and the switching speed is sub-microsecond.Then,the optical switch chip was successfully fabricated in the laboratory through spinning coating,vacuum evaporating,contact lithography,reactive iron etching(RIE),cutting and polishing process.The fabricated switch presents low power consumption of 43.6 mW.The insertion loss of the switch is-10.2 dB and the crosstalk of the switch is-34.3 dB.The response times is 550 ps,and the effective size of the device is 5 mm×0.254 mm.The device also exhibits good independence on the wavelength and driving power.The experimental results are preliminarily in agreement with the theories.A small size 2×2 total internal reflection digital thermos-optical switch was designed in order to reduce the size and power consumption of optical switching.The simulation results tell us that the size of new designed 2×2 total internal reflection digital thermos-optical switch is greatly reduced to 2.55 mm×0.127 mm,and the power consumption is 38mW,the crosstalk is-35dB.After that,the high performance 2×2 total internal reflection digital thermos-optical switch was successfully fabricated in the laboratory.The testing results show that the insertion loss is reduced to-6.2 dB,the switching power consumption is 40.3mW,the best crosstalk is up to-33.6 dB,the rise time is 320 us and the fall time is 1020 us.Obviously,the performance of optical switching is improved well.Finally,a 4-bit optical waveguide delay line was designed and fabricated based on this small size 2×2 total internal reflection digital thermo-optical switch.The results show that the delay time of the designed delay line is in the order of ps,the minimum delay is 66.4 ps,the maximum delay is 1000.3 ps,and the bending loss is-1.12 dB/cm,which meets the design expectation well.