| dc.description.abstract | Quantum technology has been gaining popularity in recent years, with a strong focus on areas such as quantum communication, known for its high security, and quantum computing, capable of solving complex problems rapidly. In these domains, photon number resolving (PNR) capabilities of photodetectors play a crucial role. Compared to single-element photodetectors that rely solely on their intrinsic capabilities for photon number resolution, array elements that use multiple component signals in parallel output can offer superior photon number resolving capabilities. Traditionally, array elements have been composed of silicon-based photodetectors or superconducting nano materials. However, this article opts for the use of III-V semiconductor materials to fabricate single photon avalanche diode (SPAD) elements for array construction. Relative to other photodetectors, III-V semiconductor-based SPADs do not require operation at extremely low temperatures like superconducting nano materials. Additionally, since III-V materials are used in the infrared spectrum, they are less susceptible to interference from visible light compared to Silicon Photomultipliers (SiPMs). Furthermore, in the field of optical communication, these SPADs can also serve as photon detectors, making them suitable for Quantum Key Distribution (QKD) in the 1550 nm wavelength range and applicable to optical fiber communication as well.
This paper presents measurements conducted using self-developed and self-fabricated InGaAs/InAlAs SPAD devices operated in gating mode. The experimental conditions were set with a gating frequency of 104.731 MHz and a laser frequency of 26.18275 MHz which has a pulse width of 1.5 ns. Additionally, self-differential circuits were employed to eliminate capacitive-coupled signals. Under the condition of an average photon number set to 1, the photon number resolving capabilities of both single-device and 2x2 array device were analyzed and compared. The single-device achieved the resolution of 5 photons at a single photon detection efficiency of 46%, whereas the array device achieved the resolution of 6 photons at a single photon detection efficiency of 14.8%. Furthermore, a comparison of the photon number resolving parameters between the two types of devices, including peak voltage separation, full-width at half-maximum, and figure of merit (FOM), demonstrated that the array device outperformed the single-device, which indicates that the array device provides superior photon number resolving capabilities over the single-device. | en_US |