A Comprehensive Survey of Photodetectors: Challenges and Novel Trends

This research presents a comprehensive exploration into the optimization of nanostructured photodetectors for enhanced infrared photodetection efficiency and the improvement of coupling efficiency in PPLN waveguide-based up-conversion Single Photon Detection (SPD) systems. The investigation centers on the absorption process within an Indium Phosphide (InP) PIN diode, leveraging its unique characteristics. Utilizing a simplified computational model and nanostructured electrodes, the study highlights the colocalization and concentration of signal and pump intensities, enhancing two-photon absorption. The proposed dimensionless nanostructure gain (G) quantifies the overall performance of the nanostructured photodetector.

Furthermore, the paper details the optical measurement setup for up-conversion SPD, employing a reverse proton-exchanged (RPE) PPLN waveguide. A novel coupling technique involving a tapered single-mode fiber significantly improves coupling efficiency. Three-dimensional finite-difference time-domain simulations validate the proposed coupling method, achieving efficiencies exceeding 96% for fiber tapers with diameters ranging from 5 µm to 7 µm. This research contributes valuable insights into optimizing nanostructured photodetectors and enhancing coupling efficiency, promising advancements in low-power infrared photodetection and up-conversion single-photon detection technologies.