The Design And Fabrication Of Polymer Thermo-optic Switches With Low Power Consumption

With the explosive growth of information requirements, construction of all optical communication network is extremely urgent. Optical switches play a very important role in all optical network as the basic building blocks of optical add-drop multiplexer (OADM) and optical cross connect (OXC), which are key components of all optical network. Due to the high thermo-optic coefficient, simple preparation process, and low cost of polymer, the research of polymer thermo-optic switches has attracted lots of attention. But the performance of polymer thermo-optic switches is not good enough. For example, the common optical switches with Mach-Zehnder interferometer (MZI), directional coupler (DC), or ring cavity have problems of sensitive to wavelength and driving power, and small process tolerance. Digital polymer thermo-optic switches could solve these problems, although the power consumption and crosstalk of the switches are high. Therefore, this paper is intended to develop the polymer thermo-optic switches which have low power consumption and low crosstalk.A 1×2 Y-branched digital polymer thermo-optic switch with low power consumption was firstly designed, based on the theories of dielectric slab waveguide, thermo-optic effect, and principle of optical switches. The simulated results show the switch has low power consumption of 20.8mW, because of the high thermo-optic coefficient of polymer and the optimized design of structure parameters. The switch was then successfully fabricated with the traditional micro-fabrication techniques, including spinning coating, vacuum evaporating, contact lithography, reactive iron etching (RIE), standard cutting and polish process. The fabricated switch presents low power consumption of 56.2mW. The insertion loss of the switch is 10.4dB and the crosstalk of the switch is -19.3dB. The measured fast rise and fall times are 366?s and 500?s respectively, due to the large thermal conductivity of silica (SiO2) under cladding. The device also exhibits good independence on wavelength and driving power. The experimental results are preliminarily in agreement with the theories.In order to further improve the characteristics of power consumption, insertion loss and crosstalk of the device, a new 1×2 digital polymer thermo-optic switch with special Y-branched waveguides and electrode structure was also presented. The simulated results show the switch not only maintains the advantage of low power consumption, but also has low crosstalk of -56dB. It was obtained through the added step of spinning coating upper cladding and improving the etching process to reduce the transmission loss. The measured results conform with the simulated results. The switch exhibits power consumption of 31.7mW, crosstalk of -40.3dB, and low insertion loss of 4.7dB. The rise and fall times are 342?s and 318?s, respectively. The experimental results show the device with new structure has small insertion loss, low crosstalk, high speed, and good independence on wavelength and driving power. It establishes the good foundation for the research of high-performance large-scale integrated waveguide optical switch array used in OXC and OADM.