Short Carbon Nanotube Nano-Film-Based Polymer/SiO₂ Hybrid Waveguide Micro-Ring Filter

A polymer/SiO₂ hybrid waveguide micro-ring filter based on a short carbon nanotube (CNT) nano-film is presented. The nano-film is coated on the top surface of the polymer waveguide, and both the nano-film and polymer waveguide serve as the core of the device. The film can effectively improve the coherent depth and quality factor values of the filter. Due to the excellent light absorption characteristic and large thermo-optic effect of the CNT nano-film, the filter shows good all-optical tunable performance. Experimental results show that its all-optical wavelength tuning efficiency reaches -0.030 nm/mW, and it is 1.67 times as much as that of the filter without the nano-film. With the CNT nano-film, its thermal sensitivity reaches 25.7 times as much as that of the filter without the film. The device shows the advantages of high tuning efficiency, small size, compact structure, and all-optical control, and it is expected to have potential applications in optical filters, optical switches, optical sensors, spectral analysis, and so on.