Design of a monolithic source of photon pairs comprising a semiconductor laser and a Bragg reflection waveguide

T. Tenzler¹, J.-P. Koester¹, H. Wenzel¹, T. Passow², Q. Yang², M. Haertelt², and A. Knigge¹

Published in:

J. Opt. Soc. Am. B, vol. 43, no. 8, pp. 1726-1733, doi:10.1364/JOSAB.596587 (2026).

Abstract:

We propose amonolithic, electrically driven source of photon pairs based on a nonlinear AlGaAs Bragg reflection waveguide and a laser structure stacked on top. By introducing lateral tapers, the fundamental mode of the lasing waveguide isvertically coupled into a higher-order mode of the Braggreflectionwaveguide(Braggmode)suchthat photon pairs can be generated through a type-II spontaneous parametric down-conversion process. According to numerical simulations, a coupling efficiency of 28% is achieved between both modes. Phase matching the Bragg mode with two fundamental modes at 1550 nm results in a photon pair rate of 1.7·10⁸ pairs/s for a 2 mm long device, assuming 1mW of power in the Bragg mode. Since the Bragg reflection waveguide does not require doping for this vertically coupled structure, free-carrier absorption losses and parasitic luminescence are avoided.

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