We report a tunable optical filter based on phase change material $Ge_{ 2}Sb_{ 2}Te_{ 5}$ embedded in a silicon microring resonator. The high thermo-optic coefficient of $Ge_{ 2}Sb_{ 2}Te_{ 5}$ in amorphous phase enables tuning of resonance wavelength in broad range with a very small active volume. The low-loss indium-tin-oxide electrodes are employed to induce Joule heating in $Ge_{ 2}Sb_{ 2}Te_{ 5}$-Si active waveguide region. The electrically induced heating in the active region alters the effective refractive index of hybrid microring resulting in a wavelength tuning of 1.04 nm for an applied voltage of only 3V. The device exhibits high extinction ratios in the range of 20-41 dB and a compact active footprint 0.96 $\mu m^{ 2}$ only and is suitable for the large scale reconfigurable integrated photonic circuits.
Categories: physics.app-ph physics.optics