Quantification of 288 K local photothermal heating and miniaturization in Si plasmonic waveguides integrated with resonators

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We report the design and fabrication of Si plasmonic waveguide local heaters with ring resonators. Quantification of the local temperature rise is reported through analysis based on the thermo-optic effect, and the heaters can be miniaturized by introducing a stronger interaction between the propagating light and matter. The resonance wavelength in the waveguide heater was shifted toward a longer wavelength by injecting TM mode light, and the shift was proportional to the light intensity. The local temperature rise was 288 K upon inputting 6.3 mW light, and the photothermal conversion efficiency was as high as 46.1 K mW−1 in a Si plasmonic waveguide loaded with 30 nm thick and 1 μm long Co thin films, showing improved characteristics compared with previous devices. Investigation toward achieving a higher efficiency is discussed based on simulation and experimental results, for realizing photothermal waveguide heaters with smaller sizes and lower input power for various applications.