Coupling Hexagonal Boron Nitride Quantum Emitters to Photonic Crystal Cavities

Abstract

Quantum photonics technologies require a scalable approach for integration of non-classical light sources with photonic resonators to achieve strong light confinement and enhancement of quantum light emission. Point defects from hexagonal Boron Nitride (hBN) are amongst the front runners for single photon sources due to their ultra bright emission, however, coupling of hBN defects to photonic crystal cavities has so far remained elusive. Here we demonstrate on-chip integration of hBN quantum emitters with photonic crystal cavities

Cavity quantum electrodynamics design with single photon emitters in hexagonal boron nitride

“…17 Even though the physical nature of these defect centers is still under investigation, h-BN has been proven as a promising platform to explore light-matter interaction and enable on-demand single photon sources, endowed with large emission rate (>10 6 counts/s), 11 strong zero-phonon emission (Debye-Waller factor, F DW ~0.8), 18 high quantum efficiency (~87%), 19 Fourier transform (FT) limited linewidth at room temperature, 18 and single photon purity even at 800 K. 20 Toward the realization of quantum functionalities based on SPEs, efficient coupling to high-quality optical devices that can direct emission into a single spatial/spectral mode and enhance the emission rate with unit efficiency is requisite. Initial experiments have demonstrated coupling of h-BN defect centers to linear photonic crystal cavities, 21,22 silicon nitride (Si 3 N 4 ) microdisk resonators, 23 and dielectric Bragg microcavities, 24 while all in weak coupling regime with Purcell factors (F P ) below 10. This is because in the emitter-cavity systems relying on heterogeneous integration, 22,23 the emission dipole is coupled to the evanescent field but not the maximum field confined inside the optical cavity.…”

Optical quantum technologies with hexagonal boron nitride single photon sources

“…Although the emission characteristic measurements in hBN were not up to the mark, quantification enhancement techniques like Two laser excitation technique, plasmonic coupling using gold nanospheres, external strain engineering, electrostatic tuning through ionic liquid devices 97 and very recently electric and magnetic field inducements 57 etc., techniques found to enhance and tune the quantum emitters emission properties and control the inhomogeneous spectral distribution. To date a record tuning of quantum emission around 65 meV 124 and higher rate of emission enhancement (around 6 to 15 fold) owing to coupling with photonic crystal cavities from silicon nitride (Si 3 N 4 ) 121 and Al nano-antenna 122 was perceived. However the quantum emitters in hBN experience spectral diffusion at cryogenic temperatures, Resonant and antistokes 154 excitation technique found to overcome the complication due to spectral diffusion.…”

“…Novel techniques to enhance the quantum emission from hBN single photon sources is by coupling the quantum emitters with photonic crystal cavities from silicon nitride (Si 3 N 4 ) 121 and Al nano-antenna 122 , which revealed a 6-fold and 10 to 15 fold enhancement in photoluminescence measurements of a hBN quantum emitter at room temperature respectively.…”

Deterministic Integration of hBN Emitter in Silicon Nitride Photonic Waveguide

“…Non‐deterministic hybrid integration of hBN in photonic circuits was recently demonstrated in aluminum nitride platform, [ 15 ] where hBN flakes were randomly dispersed on the photonic chip. Moreover, non‐deterministic hybrid integration with suspended 1D photonic crystal cavities was realized [ 16 ] through a wet transfer process of hBN to a SiN substrate. Pick and place technique for integrating hBN emitters to microcavity was demonstrated, [ 17 ] the strain induced from folding the hBN film on the resonator activates the hBN emitters.…”