Fibre-integrated SPDC heralded single-photon source using Zn-Indiffused PPLN ridge waveguides at telecom wavelengths

Peter Iveson, Paolo L. Mennea, Goronwy Tawy, Rex H. S. Bannerman, Noe Palomar-Davidson, Lewis D. Wright, Patrick M. Ledingham, Peter G. R. Smith, James C. Gates, and Corin B. E. Gawith

Abstract

We report a fibre-integrated heralded single-photon source based on a commercial Zn-indiffused MgO:PPLN ridge waveguide operated in Type-0 degenerate spontaneous parametric down-conversion (SPDC). The device emits a broadband spectrum spanning approximately 70 nm across the telecom C- and L-bands, with an absolute brightness of 9.1 × 10⁹∼pairs s⁻¹ mW⁻¹ . After accounting for optical losses, we determine an internal heralding efficiency of (58±5) %. The source demonstrates strong multi-photon suppression, exhibiting a coincidences-to-accidentals ratio exceeding 9 × 10⁴ and a heralded second-order correlation of

g ^$(2)$_h (0) = (5.53 ± 0.46) × 10^₋₄. Low multi-photon noise and broadband emission demonstrate the viability of such platforms for wavelength-multiplexed quantum networking.