Telecom wavelength quantum dots interfaced with silicon-nitride circuits via photonic wire bonding

TL;DR

This paper demonstrates the integration of telecom-wavelength quantum dots with silicon-nitride photonics using 3D laser written photonic wire bonds, enabling efficient single-photon transfer for quantum photonic circuits.

Contribution

It introduces a novel method to interface quantum dot sources with silicon-nitride photonics via 3D laser written wire bonds, facilitating platform integration.

Findings

Achieved transfer of single photons into silicon-nitride circuits with g(2)(0) = 0.11.

Funneling efficiency of approximately 28.6%.

Demonstrated compatibility at cryogenic temperatures.

Abstract

Photonic integrated circuits find ubiquitous use in various technologies, from communication, to computing and sensing, and therefore play a crucial role in the quantum technology counterparts. Several systems are currently under investigation, each showing distinct advantages and drawbacks. For this reason, efforts are made to effectively combine different platforms in order to benefit from their respective strengths. In this work, 3D laser written photonic wire bonds are employed to interface triggered sources of quantum light, based on semiconductor quantum dots embedded into etched microlenses, with low-loss silicon-nitride photonics. Single photons at telecom wavelengths are generated by the In(Ga)As quantum dots which are then funneled into a silicon-nitride chip containing single-mode waveguides and beamsplitters. The second-order correlation function of g(2)(0) = 0.11+/-0.02, measured via the on-chip beamsplitter, clearly demonstrates the transfer of single photons into the silicon-nitride platform. The photonic wire bonds funnel on average 28.6+/-8.8% of the bare microlens emission (NA = 0.6) into the silicon-nitride-based photonic integrated circuit even at cryogenic temperatures. This opens the route for the effective future up-scaling of circuitry complexity based on the use of multiple different platforms.