Optical readout of single-photon detectors
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Optical readout at cryogenic temperatures
Superconducting single-photon detectors have become one of the fundamental elements for quantum communication. These detectors achieve detection efficiencies above 90%, generate fast detection signals, and exhibit low dark noise. However, these detectors need to be operated at low temperatures (1K).
These ultra-cold temperatures are achieved within cryostats. To transmit the detection signals to the readout electronics at room temperature, fast transmission cables (coaxial cables) are used. However, these cables impose a high thermal load, limiting the number of detectors that can be operated within a signal cryostat.
As an alternative, we have developed optical interconnects that transmits both power and data using optical fibers inside the cryostat. This prototype demonstrates a significantly lower thermal load at cryogenic temperatures, allowing for the operation of substantially more detectors within a single cryostat.
To provide operational power for the detectors, we send light through a fiber optic cable, converting the light into an bias current. The electrical detection signals of the single photon detector are converted into optical signals using an optical modulator. Outside the cryostat, the detection signals can then be further processed.
In another publication, we demonstrate that the single-photon detectors can also be read out using a laser. For this purpose, the electronic detection signals are converted into optical signals using a laser diode. This technique exhibits significantly higher signal speeds.
Publications on this topic
Opto-electronic bias of a superconducting nanowire single photon detector using a cryogenic photodiode
F. Thiele, T. Hummel, M. Protte, T. Bartley, APL Photonics 7 (2022).
All optical operation of a superconducting photonic interface
F. Thiele, T. Hummel, A.N. McCaughan, J. Brockmeier, M. Protte, V. Quiring, S. Lengeling, C. Eigner, C. Silberhorn, T. Bartley, Optics Express 31 (2023).
Optical bias and cryogenic laser readout of a multipixel superconducting nanowire single photon detector
F. Thiele, N. Lamberty, T. Hummel, T. Bartley, APL Photonics 9 (2024).
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