Detector timing jitter is a key parameter in advanced photon counting applications. Superconducting nanowire single-photon detectors offer the fastest timing jitter in the visible to telecom wavelength range and have demonstrated single-photon sensitivity in the mid-infrared spectral region. Here, we report on timing jitter in a NbTiN nanowire device from 1.56 to 3.5 μm wavelength, achieving a FWHM jitter from 13.2 to 30.3 ps. This study has implications for emerging time-correlated single-photon counting applications in the mid-infrared spectral region.
Detector timing jitter is a key parameter in advanced photon counting applications. Superconducting nanowire single-photon detectors offer the fastest timing jitter in the visible to telecom wavelength range and have demonstrated single-photon sensitivity in the mid-infrared spectral region. Here, we report on timing jitter in a NbTiN nanowire device from 1.56 to 3.5 μm wavelength, achieving a FWHM jitter from 13.2 to 30.3 ps. This study has implications for emerging time-correlated single-photon counting applications in the mid-infrared spectral region.
Superconducting nanowire single-photon detectors are widely used for detecting individual photons across various wavelengths from ultraviolet to near-infrared range. Recently, there has been increasing interest in enhancing their sensitivity to single photons in the mid-infrared spectrum, driven by applications in quantum communication, spectroscopy, and astrophysics. Here, we present our efforts to expand the spectral detection capabilities of U-shaped NbTiN-based superconducting nanowire single-photon detectors, fabricated in a 2-wire configuration on a silicon-on-insulator substrate, into the mid-infrared range. We demonstrate saturated internal detection efficiency extending up to a wavelength of 3.5 μm for a 5 nm thick and 50 nm wide NbTiN nanowire with a dark count rate less than 10 counts per second at 0.9 K and a rapid recovery time of 4.3 ns. The detectors are engineered for integration on waveguides in a silicon-on-insulator platform for compact, multi-channel device applications.
Superconducting Nanowire Single photon Detectors (SNSPDs) offer unparalleled performance for IR photon counting, combining close to unity quantum efficiency, low intrinsic noise and ultrafast timing jitter. The ability of SNSPDs to count photons in mid-IR band up to 7 um wavelength opens up new possibilities in quantum optics, laser ranging, free space Quantum Key Distribution (QKD) and astronomy. Here we report on development of mid-IR SNSPDs including device design, fabrication, optimisation of superconducting materials and characterisation. We present a characterisation setup covering 1.5 - 4.2 um spectral region based on tuneable optical parametric oscillator with picosecond long pulses. We then demonstrate the viability of mid infrared SNSPDs for a variety of applications and report the results from single photon light detection and ranging (LIDAR) experiment with 2.3 um photons. This work paves the way for future app in free space QKD, deep space communication and astronomy.
Single-photon counting has become an essential tool in quantum optics experiments, as well as remote sensing and life science applications. However conventional technologies such as single-photon avalanche diodes, as well as the availability of standard telecom optical components, has limited much of this work to the near infrared/telecom wavelength range. Superconducting nanowire single photon detectors (SNSPDs) have emerged in recent years as the gold standard in photon counting applications due to their low dark count rates, fast timing resolution and high efficiency [1]. SNSPDs have also demonstrated photon counting efficiency out to much greater wavelengths which enables us to explore new experimental possibilities in the mid-infrared [2]. In this work we design and fabricate mid-infrared SNSPDs and deploy them in a variety of photon counting experiments [3,4]. The devices are based on a NbTiN superconducting film integrated into an optical cavity to enhance absorption in the mid-infrared. We characterise these devices using an optical parametric oscillator, tuneable between 1.5 m and 4.2 m. We then deploy these in a proof-of-principle tabletop light detection and ranging (LIDAR) experiment at 2.3 m. LIDAR in the mid-infrared is attractive due to spectral regions of low atmospheric absorption and reduced solar background photon flux, when compared to telecom wavelengths. We also present results from a photon-pair source operating at 2 m. This is a key resource for extending quantum optics and quantum secure communications to the mid infrared domain. Pairs are generated using a custom lithium niobate crystal and detected using SNSPDs. We demonstrate two-photon interference and polarisation entanglement of the photon pairs at 2 m. This work opens the pathway to future development of quantum optics and quantum technologies in the mid-infrared spectral region. References [1] Gol’tsman et al Applied Physics Letters 79 705 (2001) [2] Marisli et al Nano Letters 12 (9) 4799 (2012) [3] G. G. Taylor et al Optics Express 26 (27) 38147 (2018) [4] S. Prabhakar et al Science Advances 6 (13) eaay5195 (2019)
The ability to detect single photons in the mid-infrared spectral range (beyond 2 μm wavelength, photon energy below 0.62 eV) is the key to unlocking a range of emerging scientific applications, from remote sensing LIDAR, molecular spectroscopy, and powerful new approaches to dark matter detection. Conventional detector types, such as semiconductor single-photon avalanche diodes, lose sensitivity at such low photon energy. Superconducting materials, with a much lower characteristic energy gap, hold particular promise. In this Perspective, we focus on recent advances in superconducting nanowire single-photon detectors, which have recently extended single-photon sensitivity up to 29 μm (0.043 eV). We discuss the potential for future advances and strategies to overcome challenges to technological development.
We report optical characterization of NbN nanowire superconducting single-photon detectors as a function of wavelength in the near infrared. System detection efficiency decreases from ∼6% at 1.15 µm to ∼2% at 1.72 µm, while timing jitter remains relatively constant at ∼60 ps full-width-half-maximum over the range 0.7–2.0 µm. We further demonstrate the capabilities of this detector with a time-correlated single-photon counting measurement of photoluminescence from a semiconductor sample emitting at 1.65 µm.
Shortly after their inception, superconducting nanowire single-photon detectors (SNSPDs) became the leading quantum light detection technology. With the capability of detecting single-photons with near-unity efficiency, high time resolution, low dark count rate, and fast recovery time, SNSPDs outperform conventional single-photon detection techniques. However, detecting lower energy single-photons (<0.8 eV) with high efficiency and low timing jitter has remained a challenge. To achieve unity internal efficiency at mid-infrared wavelengths, previous works used amorphous superconducting materials with low energy gaps at the expense of reduced time resolution (close to a nanosecond), and by operating them in complex mK dilution refrigerators. In this work, we provide an alternative approach with SNSPDs fabricated from 5-9.5 nm thick NbTiN superconducting films and devices operated in conventional Gifford-McMahon (GM) cryocoolers. By optimizing the superconducting film deposition process, film thickness and nanowire design, our fiber-coupled devices achieved > 70% system detection efficiency (SDE) at 2 μm and sub-15 ps timing jitter. Furthermore, detectors from the same batch demonstrated unity internal detection efficiency at 3 μm and 80% internal efficiency at 4 μm, paving the road for an efficient mid-infrared single-photon detection technology with unparalleled time resolution and without mK cooling requirements.