Asymptotic-field approach for the control of dipole emission in integrated structures

Wepresent ageneral framework to modelspontaneous emission in integrated photonic structures by exploiting quantization of the electromagnetic field in terms of asymptotic-in/out modes. This approach allows for an efficient and physically meaningful calculation of the emission rate into each radiative channel of an arbitrary structure, without relying on approximations such as Lorentzian lineshapes or point-like system-bath coupling. We show that with this approach one can recover well-known results for dipole emission in waveguides or ring resonators, and that such results can be easily extended to include the effect of backscattering. Finally, as an application, we design a tunable integrated single-photon source that enables full control over both the emission rate and output mode. This flexibility makes our method particularly well suited for the design and analysis of integrated single-photon sources in various material platforms.