Thermo-optic wavelength tunable filter using polymer optical waveguides for WDM systems

We have developed a polymer thermo-optic (TO) wavelength tunable filter that can select any wavelength division multiplexed (WDM) channel from among WDM channels. This tunable filter should have a wide tuning range because polymer materials as waveguides have a large TO coefficient. We evaluated its suitability for use in LAN systems, its long-term operating stability, its tunability over a wide wavelength range, and its responsiveness. We demonstrated its applicability to LAN systems and its stable operation by testing it in the feedback system of a filter with a 9-nm tuning range. We developed a tunable filter with a pair of triangular phase shifters on arrayed waveguides that provide fast response and wideband tunability. This filter had crosstalk less than -30 dB, tunability wider than 20 nm, and a response time less than 60 ms.