Abstract
Active imagers capable of reconstructing 3-dimensional (3D) scenes in the presence of strong background noise are highly desirable for many sensing and imaging applications. A key to this capability is the time-resolving photon detection that distinguishes true signal photons from the noise. To this end, quantum parametric mode sorting (QPMS) can achieve signal to noise exceeding by far what is possible with typical linear optics filters, with outstanding performance in isolating temporally and spectrally overlapping noise. Here, we report a QPMS-based 3D imager with exceptional detection sensitivity and noise tolerance. With only 0.0006 detected signal photons per pulse, we reliably reconstruct the 3D profile of an obscured scene, despite 34-fold spectral-temporally overlapping noise photons, within the 6 ps detection window (amounting to 113,000 times noise per 20 ns detection period). Our results highlight a viable approach to suppress background noise and measurement errors of single photon imager operation in high-noise environments.
Highlights
Active imagers capable of reconstructing 3-dimensional (3D) scenes in the presence of strong background noise are highly desirable for many sensing and imaging applications
The pump and probe pulses are carved from a 50 MHz femtosecond mode-locked laser (MLL) using separate sets of cascaded spectral filters
The pump pulses are sent to a programmable optical delay line (ODL)
Summary
Active imagers capable of reconstructing 3-dimensional (3D) scenes in the presence of strong background noise are highly desirable for many sensing and imaging applications. Undesirable photons in other modes, even if they spectrally and temporally overlap with the signal, are converted with much less efficiency[27,28] This exotic mode selectivity realizes superior nonlinear-optical filtering, which was demonstrated to achieve detection signal to noise more than 40 dB over a linear-optical filtering and detection system, and beat the theoretical limit of an ideal matched filter by 11 dB22,29. The signal to noise advantage is 36 dB over direct detection using an InGaAs single photon detector with a 1 ns gated detection window[29], or 7 dB above the theoretical limit of ideal linear-optical matched filters[22] This allows active 3D imaging in a scenario where the background is orders of magnitude stronger than the backscattered signal, with 34 times more spectral-temporally overlapping noise than signal photons. We highlight the extreme ranging resolution of our imaging technique by imaging through a highly reflective obscurant without being impeded by the pileup distortions, dead time, and count rate saturation issues that plague many other single photon imagers
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