Backside-etched SNSPDs with enhanced system detection efficiency at 1064 nm.

Area of Science:

• Photonics and Optoelectronics
• Quantum Technologies
• Materials Science

Background:

• Superconducting nanowire single-photon detectors (SNSPDs) commonly achieve high system detection efficiency (SDE) at 1550 nm.
• Practical multimode fiber-coupled SNSPDs at 1064 nm face challenges with stable, high SDE due to absorption and polarization sensitivity.

Purpose of the Study:

• To develop a backside-etched SNSPD design for improved SDE at 1064 nm.
• To address absorption losses in silicon substrates and polarization sensitivity of nanowires.

Main Methods:

• Incorporation of a titanium dioxide layer into the optical cavity to suppress polarization sensitivity.
• Implementation of an additional dry etching step to reduce silicon substrate absorption loss.
• Fabrication and experimental testing of the optimized SNSPD design.

Main Results:

• Achieved a system detection efficiency (SDE) of 67% at 1064 nm.
• Demonstrated minimum SDE exceeding 64% across all polarization states.
• Reduced silicon substrate absorption loss from 25% to less than 5%.

Conclusions:

• The developed backside-etched SNSPD offers a high-performance solution for 1064 nm applications.
• This advancement enables broader applications in lidar, satellite laser ranging, and industrial manufacturing.
• The design effectively mitigates polarization sensitivity and absorption losses.