TIR Switch Exploits Polyimide Attribute

The refractive index of polyimide decreases as its temperature increases. Researchers at the University of Texas in Austin harnessed this polymeric attribute to develop a total- internal-reflection (TIR) waveguide switch with an X junction. A heater at the junction controls the pathway of light, forming a 2 x 2 nonblocking switch with less than -28 dB crosstalk.

The work, published in the Oct. 14 issue of Applied Physics Letters, reports switching power of about 132 mW, which can drop to 20 or 30 mW with improvements to the drive efficiency. The device's average insertion loss is 10 dB, and its switching speed is in the millisecond range.