Photoluminescence Enhancement of InSe by Coupling with Circular Bragg Grating

Abstract

Indium selenide (InSe) has attracted tremendous research interest due to its excellent optical and electronic properties. The direct bandgap of bulk InSe promises efficient carrier recombination in the near‐infrared (NIR) spectral range, holding great potential for NIR‐based optoelectronic device applications. However, the lowest energy transition in InSe involves out‐of‐plane optical dipoles, with resulting photoluminescence (PL) transmitted mainly along the layer plane. This limits both optical excitation and detection efficiency along the surface normal for practical device operation. To circumvent this issue, here, bulk InSe flake is coupled with circular Bragg grating (CBG) fabricated on silicon substrate by focused ion beam milling. A maximal 60‐fold PL enhancement is achieved, with Purcell effect‐facilitated carrier recombination and improved light out‐coupling via CBG contributing jointly. The same device architecture is further demonstrated to boost the second harmonic generation by a factor of 34. The results provide an effective way to enhance the optical performance of III–VI layered nanomaterials for both linear and nonlinear optoelectronic device applications.

Room-Temperature Magnetic-Induced Circularly Polarized Photoluminescence in Two-Dimensional Er2O2S

“…As 2D materials have reported with thickness-dependent properties, thickness-dependent emission of Er 2 O 2 S flakes was studied. , As thickness increases from 8.1 to 121.6 nm, emission intensities also increase. Thickness-dependent photoluminescence quantum yield (PLQY) of Er 2 O 2 S flakes in Figure S4 also increases with thickness increasing, which is consistent with the PL intensity because of increasing Er 3+ ions participating in radiative recombination processes. , Other than thickness, temperature also has significant impact on the PL properties of luminescent materials. , As shown in Figure S5, PL intensity, PLQY, and decay lifetimes of Er 2 O 2 S continuously decrease as temperature increases, which results from the increased activity of phonons that leverages the nonradiative relaxation with increasing temperature. ,− Power-dependent emissions of two different thicknesses were characterized (8.1 nm in Figure b and 121.6 nm in Figure c). With the increase of laser power, emission intensities all enhance linearly with power-law fitted slopes at around 1, indicating a single-photon absorption. , Therefore, Figure d shows the proposed emission mechanism: (1) electrons are first excited to 4 S 3/2 from 4 I 15/2 ; (2) electrons relax to 4 F 9/2 by the nonradiation; and (3) electrons drop to 4 I 15/2 and emit green and red PL.…”

“…39,40 Other than thickness, temperature also has significant impact on the PL properties of luminescent materials. 41,42 As shown in Figure S5, PL intensity, PLQY, and decay lifetimes of Er 2 O 2 S continuously decrease as temperature increases, which results from the increased activity of phonons that leverages the nonradiative relaxation with increasing temperature. 35,43−45 Power-dependent emissions of two different thicknesses were characterized (8.1 nm in Figure 2b and 121.6 nm in Figure 2c).…”

Improved optical performance in circular-grating distributed feedback nanoplasmonic lasers

“…To further control the mode in group and spatially, a second-order distributed feedback circular grating is used for optical coupling with VCSELs. Such circular-symmetric grating lasers, operating in distributed feedback (DFB) or distributed Bragg reflector (DBR) configurations, produce circular-symmetric output beams of single longitudinal mode [23], multiple transverse mode, and low divergence, which have been confirmed in several reports [24][25][26][27][28].…”

Monolithic Integration of Single Quantum Emitters in hBN Bullseye Cavities

“…The circular Bragg grating (CBG) has been a popular approach to addressing this need. Enhanced collection efficiency from CBG structures has been reported for various SPS platforms, including self-assembled quantum dots (QDs), − colloidal QDs, , bulk diamond and nanodiamond, and CBGs have also been used to enhance excitonic bandgap emission. , In hBN, ensemble emission from the boron vacancy spin defect was enhanced using monolithic integration with a CBG device, and the recently discovered 436 nm quantum emitter, termed B-center, was coupled to a waveguide and the emission efficiently collected using a semicircular Bragg-style output coupler . Early works on QDs and diamond etched the CBG structure into an existing host material containing a nominal density of single-photon emitters, resulting in a low probability of cavity coupling.…”