Single-photon detector for long-distance fiber-optic quantum key distribution

Area of Science:

• Optoelectronics
• Quantum Information Science
• Semiconductor Devices

Background:

• Avalanche photodiodes (APDs) are critical for detecting single photons.
• InGaAs/InP APDs are suitable for 1550 nm telecom wavelengths.
• Thermoelectric cooling is essential for reducing dark counts in photon detectors.

Purpose of the Study:

• To evaluate the performance of an InGaAs/InP avalanche photodiode for single-photon counting.
• To assess the detector's characteristics under thermoelectric cooling.
• To determine the potential of the detector for quantum communication applications.

Main Methods:

• Investigated InGaAs/InP avalanche photodiode performance.
• Operated the detector within a thermoelectric cooling temperature range.
• Measured quantum efficiency and dark-count probability per gate.

Main Results:

• Achieved a quantum efficiency of 13.7% at -55 degrees C.
• Maintained a low dark-count probability of 2.4x10^-5 per gate (approx. 1 ns).
• Demonstrated potential for 104.4-km fiber-optic quantum key distribution.

Conclusions:

• The InGaAs/InP avalanche photodiode exhibits excellent performance for photon counting.
• Thermoelectric cooling enables high efficiency and low noise operation.
• The detector is a promising candidate for secure, long-distance quantum communication.