The top-notch of light detection: SNSPDs

Operation principle of SNSPD

Superconducting Nanowire Single Photon Detectors

The SNSPD consists of a thin film of superconducting material shaped into a meandering nanowire through nanofabrication processes. This pattern enables it to cover a wide surface area, collecting the whole output of an optical fiber, while constituting a single path for the current. The detectors are operated at 2.5 Kelvin and a constant current below the critical current of the superconductor is applied to the device. The nanoscale cross section gives our photon detectors an extremely high level of sensitivity upon absorption of just a single photon.

Once a single photon is absorbed in the meandering nanowire, superconductivity is locally broken. As a result, the current is directed towards the amplification electronics and creates a voltage pulse. After the photon is absorbed, superconductivity recovers in the nanowire within a short time (tens of nanoseconds) and the SNSPD is ready to detect the next photon.

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The fastest detectors on the market

Photon detection with high time resolution

In applications such as the lifetime measurement of photoluminescence and photon correlation measurements, high time resolution of photon detectors is of great importance. The time resolution of single photon detectors is characterized by the full width at half maximum (FWHM) of the variation in the temporal delay from the absorption of a photon to the generation of an output electrical pulse, which is defined as the timing jitter.

Single Quantum SNSPDs have demonstrated the lowest timing jitter on the market, achieved thanks to the cryogenic amplification.

A cryogenic amplifier, encased and mounted to the 40K stage of the cryostat, enables the SNSPDs to reach the highest single-to-noise ratio and thus the optimal timing jitter. A typical Single Quantum SNSPD with a cryogenic amplifier reaches <15 ps timing jitter.