Room temperature photon-counting lidar at 3  µm.

Area of Science:

• Photonics and Optical Engineering
• Laser Technology
• Remote Sensing

Background:

• Mid-infrared (3 µm) lidar offers potential for high-resolution remote sensing.
• Conventional detectors at 3 µm are often inefficient or costly.
• Upconversion techniques can enable detection of infrared photons using visible-light detectors.

Purpose of the Study:

• To develop and demonstrate a mid-infrared single-photon-counting lidar system operating at 3 µm.
• To investigate the feasibility of upconverting 3 µm photons for detection with silicon single-photon avalanche detectors (SPADs).

Main Methods:

• A 3 µm single-photon-counting lidar system was constructed.
• Intracavity mixing within a 1064 nm Nd:YVO4 laser upconverted 3 µm photons to 790 nm.
• Upconverted photons were detected using a standard silicon SPAD and time-tagging electronics.

Main Results:

• The lidar system successfully detected single photons at 3 µm.
• Millimeter-deep features on a diffusely reflecting target were resolved.
• System performance was limited by the SPAD and associated electronics.

Conclusions:

• The presented upconversion technique enables single-photon detection at 3 µm using conventional silicon SPADs.
• This approach provides a viable pathway for developing advanced mid-infrared lidar systems.
• The technique is extensible to longer wavelengths compatible with the nonlinear crystal's transparency.