Coupling-Controlled Multiport Thermo-Optic Switch Using Polymer Waveguide Array

Abstract

A multiport thermo-optic switch based on parallel polymer waveguides and microheater array is proposed. The basic unit is a 1 × 3 switch for Up Transfer, Isolation, and Down Transfer operations. By introducing refractive index perturbation along the selected waveguides through microheaters, the Transfer /Isolation condition can be switched locally, and light is then steered into different paths. A 1 × 5 switch is demonstrated experimentally as an example. Colorless (1.50 μm to 1.62 μm) and polarization independent operation is achieved with crosstalk suppression ratio larger than 10 dB, which can be further optimized. The design requires less waveguides and tuning sections than conventional Mach-Zehnder interferometer-based switches. 6 microheaters are placed but only 3 need to be powered on simultaneously to reach any of the 5 output ports. The maximal heater power is 33.8 mW over a coupling length of 1331.6 μm. This design can easily scale up to form an arbitrary cascaded M × 1 and 1 × N switch network for high-density photonic integration.