Quantum technologies hold the promise of revolutionizing computing, communication, and sensing, and integrated photonics stands as a key enabler in this realm. Silicon nitride, with its unique combination of low loss, remarkable non-linear performance, and compatibility with existing semiconductor technologies, has emerged as a promising candidate for the implementation of quantum photonic circuits. Alternately, Lithium-Niobate-OnInsulator (LNOI), a material platform well known for its high electro-optic coefficient, has also turned out to be an attractive choice for quantum integrated circuits with the development of low-loss fabrication processes. Moreover, the integration of on-chip photon sources and superconducting nanowire single-photon detectors (SNSPDs) on these platforms has paved the for scalable quantum circuits minimizing the footprint and eliminating the need for lossy interconnects. However, the integration of these components on a single material platform is often hindered by background photons from the strong classical pump light used for processes such as spontaneous parametric down-conversion (SPDC). Here, we propose silicon-implanted SiN and LNOI waveguides as a novel material platform that acts as a passive filter at visible wavelengths while imparting negligible losses in the telecom band. The implantation process can be selectively patterned with manometer precision enabling enhanced tunability of the process. Furthermore, transmission electron microscopy (TEM) results provide a thorough understanding of the material dynamics at the atomic scale allowing accurate modelling of the mode profiles. This breakthrough advances the scalability of quantum photonic technologies where the source, filters, circuits, and detectors can be integrated on a single platform.
The recent discovery of room-temperature intrinsic single-photon emitters in silicon nitride (SiN) 1 provides a unique opportunity for seamless monolithic integration of quantum light sources with the well-established SiN photonic platform. In this work, we successfully demonstrate the integration of intrinsic quantum emitters with planar waveguides composed of low-autofluorescence SiN and demonstrate single-photon emission coupling into the waveguide mode. The coupling of single-photon emission to the waveguide mode is confirmed by second-order autocorrelation measurements of light outcoupled off the photonic chip by grating couplers. Fitting the second-order autocorrelation histogram yields g (2) (0) = 0.15 ± 0.09 without spectral filtering or background correction, the outcoupled photon rate derived from saturation measurements is found to be 6 × 10 3 counts per second. This demonstrates the first successful coupling of photons from monolithically integrated SiN intrinsic single-photon emitters with waveguides composed of the same material. The results of our work pave the way toward the realization of scalable, technology-ready quantum photonic integrated circuitry efficiently interfaced with solid-state quantum emitters.