  We present a novel design of a superconducting nanowire single photon
detector (SNSPD) fabricated on a core of a single mode optical fiber. The
proposed design allows high overlap between the fiber light mode and the
detector, and consequently, our fabricated devices can remain small in
dimension and maintain speed of operation, without scarifying the detection
efficiency. The on-fiber fabrication method is detailed, together with
experimental results. The proposed method can be exploited in the future for
the fabrication of other fiber coupled devices.
