Structural design of a mid-infrared low-noise waveguide photodetector integrated with an ultra-short waveguide taper

Abstract

Mid-infrared waveguide photodetectors, offering advantages such as high bandwidth, low power consumption, and ease of integration, are highly suitable for applications in spectral detection and molecular fingerprint recognition. To enhance the sensitivity and signal-to-noise ratio of waveguide photodetectors, this paper demonstrates the structural design of a mid-infrared waveguide photodetector integrated with an ultra-short waveguide taper. The proposed structure compresses the fiber-coupled optical field to subwavelength dimensions, effectively decreasing the area of the integrated absorber while maintaining quantum efficiency, thus achieving low dark current noise. The total length of the ultra-short waveguide taper has been reduced by an order of magnitude compared to the conventional waveguide taper. Simulation results indicate a one-order-of-magnitude reduction in dark current and a 68.2% reduction in noise equivalent power compared to the device without a waveguide taper. Our work presents a novel design approach for developing low-noise, highly integrated waveguide photodetectors.