Innovative direct manufacturing of tungsten carbide superconducting nanowires for photon detection applications via pulsed focused ion beam induced deposition

We present the development and optical characterization of tungsten carbide superconducting nanowire devices for photon detection. They are nanofabricated by direct deposition via pulsed focused ion beam induced deposition (PFIBID) using Tungsten Hexacarbonyl (W(CO)₆) as precursor. The nanowires exhibit a critical temperature of 4.71 K and demonstrate a notable response to low-intensity CW or pulsed laser illumination. For the first time, in-operando photoresponse low-temperature maps reveal hotspot distributions under low power illumination and localized superconductivity suppression upon high fluence photon absorption at higher powers. Dynamic response measurements under 1 MHz repetition rate, 640 nm pulsed laser excitation highlight the fast temporal response of the detectors and high operation stability near saturation. While currently operating in the multi-photon regime (9 photons/output-pulse), the findings emphasize their potential for single-photon detection with further optimization of material thickness (target <25 nm) and excitation schemes. This work demonstrates the significant promise to direct nanofabricate superconducting devices based on WC for advanced quantum applications.