HRL Pursues Tunable, Long-Wavelength Single Photon Detection
New approach leverages proximity effect induced in superconductor-semiconductor heterostructures
HRL Laboratories will develop a new generation of electrically tunable, long-wavelength superconducting nanowire single-photon detectors (SNSPDs) as part of a DARPA project which will enable a much wider variety of applications for the technology.
MALIBU, Calif. July 1, 2024— HRL Laboratories, LLC, will develop a new generation of electrically tunable, long-wavelength superconducting nanowire single-photon detectors (SNSPDs) as part of the SynQuaNon program sponsored by the Defense Advanced Research Project Agency (DARPA).
Traditional, single-material SNSPDs are the state-of-the-art choice for various quantum photonics and low-light applications at telecom wavelengths (1.3 and 1.55 micron light), but these SNSPDs do not have good sensitivity at longer wavelengths. The goal of this project is to develop a novel type of SNSPD that is capable of sensing wavelengths longer than 2 microns.
“This infrared regime is extremely important for free-space applications such as 3D imaging/mapping for navigation and target acquisition, remote sensing, space-based and quantum communication,” said Dr. Minh Nguyen, principal investigator for HRL’s project. “When not constrained by the wavelength requirements of optical fibers, free-space applications employing longer wavelengths have multiple benefits: more available high-power lasers, higher maximum (eye-safe) permissible exposure level, and more waveband security. Moreover, extending the detector’s response to longer wavelengths offers richer spectral information such as bio/chemical absorption signatures, new atmospheric transmission windows, and special infrared phenomenology.”
HRL will use the superconducting proximity effect induced in superconductor-semiconductor heterostructures to realize these novel tunable single-photon detectors in the project named “Proximitized Patterned Heterostructures for Superconducting Nanowire Single Photon Detectors (ProPHet for SNSPDs).” These proximitized materials can allow for greater engineering of their superconducting and normal state properties. Many quantum technologies today are made from either superconductors or semiconductors due to the special properties of each type of material. However, devices like proximitized detectors that combine their distinctive properties may open up even more avenues for new capabilities.
Despite the rapid progress in SNSPD technology in recent years for the visible and short-wave infrared regimes, obtaining high-efficiency SNSPDs with a cut-off longer than 2 microns is particularly challenging. Such devices often have stringent requirements such as very narrow (~30 nanometers) nanowire width that is difficult to fabricate at large scale or operation at very low temperature (<1K) that requires bulky and expensive 3He-based cooling systems. “By leveraging the unique properties of proximitized semiconductors, it may be possible to make high-performing detectors which are easier to manufacture and operate at higher temperatures compared to conventional SNSPDs,” said Dr. Andrew Pan, principal investigator at HRL for a sister SynQuaNon Disruption Opportunities (DO) modeling effort, which is giving HRL a head start in understanding the technical requirements and possibilities of this approach.
“HRL’s custom fabrication facilities uniquely position us to bring to life novel, complex structures that require a delicate interplay of material interfaces and nanometer-size features. Our semiconductor and superconductor growth expertise, combined with our advanced in-house testing capabilities, have positioned us for success on this program,” said Dr. Brett Yurash, co-principal investigator and device measurement lead at HRL.
In addition, the electrostatic tunability of this concept can open a new realm of dynamic operation with active feedback control. For example, on-chip multiple/hyperspectral detection can be achieved by shifting the detection efficiency curve using the gate bias. In another example, increasing gate bias in response to a detection event can rapidly modulate the proximitized coupling strength, potentially allowing faster detector recovery to its superconducting state than the passive cooling process in conventional SNSPDs. Likewise, in an SNSPD array configuration, the individually addressable gates can selectively turn on and off individual detector elements, enabling a simple readout scheme for imaging arrays.
This material is based upon work supported by the Defense Advanced Research Projects Agency (DARPA) under Contract No. HR0011-24-C-0442. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Defense Advanced Research Projects Agency (DARPA).
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