Low-power thermo-optic tuning of vertically coupled microring resonators

InP/InGaAsP vertically coupled microring resonators fabricated with polymer (BCB) waferbonding are presented. Due to the low thermal conductivity of the polymer, thermo-optic tuning of the microring resonators is very efficient. A tuning range of 16 nm with a power input of 50 mW is demonstrated.