Thermally optimized variable optical attenuators on a polymer platform

Variable optical attenuators based on a 1 x 1 multimode interference device (MMI) and a Mach-Zehnder interferometer (MZI) have been designed, fabricated, and characterized. Thermo-optic simulations have been performed to find the optimal heater electrode layout in order to improve the heating efficiency, suppress thermal crosstalk, and enhance the dynamic attenuation range. Both types of attenuators feature low optical loss (<0.7 dB). The compact 1 x 1 MMI provides a dynamic attenuation range of 35 dB over the C band at 10.1 mW heater power, while the MZI increases the dynamic range beyond 50 dB at merely 1.8 mW heater power.