High Q InGaAsP ring resonator filters

We present the results of measurements on passive InGaAsP ring filters. The rings have a radius of 125 mum and coupler lengths around 80 mum. Using the transmission and reflection spectra, we derived a number of quantities such as the power coupling loss and roundtrip loss. The different behaviour of the TM mode and the TE mode is measured and explained. The rings show a Finesse of 15 (TE) and 3 (TM) and a Q factor of 38000 (TE) and 7500 (TM).