Improvement of photothermal heating efficiency of Si plasmonic waveguide heaters with ring resonators

We report improved photothermal heating efficiency of Si plasmonic waveguide heaters integrated with ring resonators by enhancing the interaction of the propagating light and metal with a thinner buffer layer. The resonance wavelength was shifted towards a longer wavelength by inputting transverse magnetic mode light, and the amount of shift was influenced by the length of the region deposited with the Co thin film and the gap of the directional coupler. The local temperature rise of 580 K was achieved by injecting 6.3 mW of light, and photothermal conversion efficiency as high as 106 K mW −1 was obtained in a Si plasmonic waveguide deposited with 0.5 μ m long Co thin films, showing improvement compared with previous devices. Discussion on the heating efficiency based on the propagation loss and cavity loss in the ring resonators is given based on experimental results, to realize compact photothermal waveguide heaters for various applications.