Ryan M. Briggs

Single-photon time-of-flight light detection and ranging (LiDAR) is a versatile technique for the measurement of absolute distances and for depth profiling. It has a wide variety of applications (e.g., land surveying, autonomous car navigation, underwater imaging) with the potential to achieve high-resolution three-dimensional images over long ranges when the key components of the measurement system are of a suitably high specification. In this work, a novel, high-efficiency, and low timing jitter superconducting nanowire single-photon detector, in conjunction with a custom single-pixel scanning transceiver system, and the time-correlated single-photon counting technique, enable the acquisition of millimeter-scale resolution depth images of scenes at standoff distances of hundreds of meters. A 1550 nm wavelength fiber laser was coupled to the monostatic transceiver to provide the illumination. The system was eye-safe with the maximum average optical output power being ≤3.5mW for measurements of a scene at a standoff distance of 1 km. The overall system instrumental response was approximately 13 ps full width half maximum. This enabled 1 mm depth features on a reference board and a human head to be clearly resolved when measured by the system in broad daylight at standoff distances of 45 and 325 m using per-pixel acquisition times of between 0.25 and 1 ms. These high-resolution results demonstrate the enormous potential of such a system to acquire detailed depth and intensity images of scenes from long distances in daylight or darkness conditions. This could lead to step change improvements in applications such as facial and human activity recognition and the imaging of scenes through clutter and atmospheric obscurants.

Optical frequency comb is an enabling technology for a multitude of applications from metrology to ranging and communications. The tremendous progress in sources of optical frequency combs has mostly been centered around the near-infrared spectral region, while many applications demand sources in the visible and mid-infrared, which have so far been challenging to achieve, especially in nanophotonics. Here, we report widely tunable frequency comb generation using optical parametric oscillators in lithium niobate nanophotonics. We demonstrate sub-picosecond frequency combs tunable beyond an octave extending from 1.5 up to 3.3 μm with femtojoule-level thresholds on a single chip. We utilize the up-conversion of the infrared combs to generate visible frequency combs reaching 620 nm on the same chip. The ultra-broadband tunability and visible-to-mid-infrared spectral coverage of our source highlight a practical and universal path for the realization of efficient frequency comb sources in nanophotonics, overcoming their spectral sparsity.

Widely tunable coherent sources are desirable in nanophotonics for a multitude of applications ranging from communications to sensing. The mid-infrared spectral region (wavelengths beyond 2 μm) is particularly important for applications relying on molecular spectroscopy. Among tunable sources, optical parametric oscillators typically offer some of the broadest tuning ranges; however, their implementations in nanophotonics have been limited to narrow tuning ranges in the infrared or to visible wavelengths. Here, we surpass these limits in dispersion-engineered periodically poled lithium niobate nanophotonics and demonstrate ultrawidely tunable optical parametric oscillators. Using 100 ns pulses near 1 μm, we generate output wavelengths tunable from 1.53 μm to 3.25 μm in a single chip with output powers as high as tens of milliwatts. Our results represent the first octave-spanning tunable source in nanophotonics extending into the mid-infrared, which can be useful for numerous integrated photonic applications.

Widely-tunable coherent sources are desirable in nanophotonics for a multitude of applications ranging from communications to sensing. The mid-infrared spectral region (wavelengths beyond 2 $\mu$m) is particularly important for applications relying on molecular spectroscopy. Among tunable sources, optical parametric oscillators typically offer some of the broadest tuning ranges; however, their implementations in nanophotonics have been limited to narrow tuning ranges and only at visible and near-infrared wavelengths. Here, we surpass these limits in dispersion-engineered periodically-poled lithium niobate nanophotonics and demonstrate ultra-widely tunable optical parametric oscillators. With a pump wavelength near 1 $\mu$m, we generate output wavelengths tunable from 1.53 $\mu$m to 3.25 $\mu$m in a single chip with output powers as high as tens of milliwatts. Our results represent the first octave-spanning tunable source in nanophotonics extending into the mid-infrared which can be useful for numerous integrated photonic applications.

We demonstrate large-area superconducting nanowire single-photon detectors (SNSPDs) for operation in the mid-IR band, up to 7.4 μm.

We demonstrate large-area superconducting nanowire single-photon detectors (SNSPDs) with simultaneous high system detection efficiency and low system jitter. We describe the device architecture and discuss optimal readout setup for practical applications.