  Current crowding at bends of superconducting nanowire single-photon detectors
is one of the main factors limiting the performance of meander-style detectors
with large filling factors. In this paper, we propose a new concept to reduce
influence of the current crowding effect, a so-called variable thickness SNSPD,
which is composed of two regions with different thicknesses. A larger thickness
of bends in comparison to the thickness of straight nanowire sections locally
reduces the current density and reduces the suppression of the critical current
caused by the current crowding. This allows variable thickness SNSPD to have a
higher critical current, an improved detection efficiency, and decreased dark
count rate in comparison with a standard uniform thickness SNSPD with an
identical geometry and film quality.
