Optical Photon Number Resolving Detector by Parallel-Segmented Transition Edge Sensor with Single Bias Operation

Abstract We propose the parallel segmentation of the sensitive area of the optical transition edge sensor. The aim of parallel segmentation is to enhance the timing properties of the TES particularly in its rising edge by confining each heat diffusion event inside a segment and hence reducing the time required for the rise in resistance. All the segments are operated by a single voltage bias. We select iridium as its material and fabricated a two-segment device using photolithography and dry etching. The static characteristics were compared with a non-segmented device. We demonstrated the photon number resolving capability at the wavelength of 1547 nm and the parallel-segmented device exhibited an energy resolution of ΔE = 0.658 eV in FWHM using a SQUID readout. The electro-thermal simulations by finite difference method were performed to compare the timing properties among the different geometries including parallel-segmented structure.