Microcavity-coupled emitters in hexagonal boron nitride

Abstract

<jats:title>Abstract</jats:title><jats:p>Integration of quantum emitters in photonic structures is an important step in the broader quest to generate and manipulate on-demand single photons via compact solid-state devices. Unfortunately, implementations relying on material platforms that also serve as the emitter host often suffer from a tradeoff between the desired emitter properties and the photonic system practicality and performance. Here, we demonstrate “pick and place” integration of a Si<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub> microdisk optical resonator with a bright emitter host in the form of ∼20-nm-thick hexagonal boron nitride (hBN). The film folds around the microdisk maximizing contact to ultimately form a hybrid hBN/Si<jats:sub>3</jats:sub>N<jats:sub>4</jats:sub> structure. The local strain that develops in the hBN film at the resonator circumference deterministically activates a low density of defect emitters within the whispering gallery mode volume of the microdisk. These conditions allow us to demonstrate cavity-mediated out-coupling of emission from defect states in hBN through the microdisk cavity modes. Our results pave the route toward the development of chip-scale quantum photonic circuits with independent emitter/resonator optimization for active and passive functionalities.</jats:p>

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.…”

“…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. Moreover, a wide spectral range of emission has been observed from h-BN, with zero-phonon lines (ZPLs) spanning from ultraviolet (UV) to near-infrared (NIR) wavelengths.…”

Review on coherent quantum emitters in hexagonal boron nitride

“…The two-dimensionality entails that the nanoflakes can be positioned with high precision, for example in regions of highest fields in plasmonic devices, which results in the generation of a nonlinear optical response with highest efficiency even for low-power, CW-laser excitation [27] as depicted in Figure 2 (A). The fact that h-BN is a twodimensional material, conditions that the incorporated defect centers are located directly at the host surface, which makes it an ideal platform for evanescent integration into plasmonic and photonic devices [29]. Besides applications originating from the evanescent coupling, the h-BN-material enables direct structuring of photonics devices into the host material [30].…”

“…The axial distance as well as the full dipolar orientation was determined for defect centers in multi-layer h-BN flakes by modification of the photonics density of states via phasechanging optical materials (VO 2 ) [101]. Examples of hybrid quantum photonics include defect centers in h-BN optically coupled to nanofibers [102], Si 3 N 4 microdisk optical resonators [29], waveguides [103,104], metallo-dielectric antennas [105] and Si 3 N 4 photonic crystal cavities [106]. Recently, ensemble defect centers in h-BN nanoflakes were coupled to nanofiber Bragg cavities by advanced pick and place technique [96].…”

Deterministic Integration of hBN Emitter in Silicon Nitride Photonic Waveguide

“…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. Position and spectral control of hBN single‐photon emitters was also reported, [ 18 ] which opens exciting avenues for controlled integration of hBN emitters.…”