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

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.