On-Chip Optical Waveguide Visible-Light Power Detector Based on Photothermal Effect of PPy/SU-8 Photopolymer

In this work, an all-optical on-chip polymer waveguide visible-light power detector is proposed based on photothermal effect of polypyrrole (PPy) nanoparticles. PPy/SU-8 waveguide material is prepared and the strong optical absorption of the photopolymer in the visible-light region is beneficial for efficient photothermal energy conversion. The photothermal characteristics of PPy/SU-8 are analyzed, and through selective absorption specificity of the PPy/SU-8 photopolymer in Vis-NIR region, the performances of the multimode interference (MMI) waveguide device by thermo-optic (TO) tuning are simulated. The pho- tothermal energy conversion coefficient of the PPy/SU-8 waveguide is obtained as 2.5 K/mW. The actual sensitivity of the on-chip light power detector is measured as 2.3 nm/mW. This technique could be used to achieve ultra-compact on-chip all-optical detectors in future.