GaN Ultraviolet Laser based on Bound States in the Continuum (BIC)

Abstract

structures. The optical BIC states in a wave system have been widely discussed and utilized. The quasi-BIC effect was first reported in passive systems in the form of a 1D line-and-space periodic structure. [6] Subsequently, some passive devices utilizing BIC modes supported in metallic metasurfaces, [7,8] dielectric metasurfaces, [9][10][11] and photonic elements [12,13] are demonstrated. In an active device, a BIC mode can support narrow-linewidth lasing with a smaller device size down to a few dozen periods of the BIC structure, which makes it possible for the laser device to be integrated at high density onto a chip. [14] Due to these advantages of BIC in light confinement, BIC-supported lasers in the NIR range were realized. [14][15][16][17] The lasing emission is observed from a nanoarray structure having feature sizes smaller than 10 µm. Later, BIC-supported lasers were realized in the visible range. [18][19][20][21][22][23][24] A highspeed optical switch with vortex lasing emission is also realized via BICs in the visible range. However, a BIC-supported nanolaser emitting in the ultraviolet (UV) has not yet been reported.With wavelengths ranging from 200 to 400 nm, UV nanolasers hold important applications in high-resolution bioimaging, laser therapy, spectroscopy, lithography, and optical storage. GaN with a wide direct bandgap of 3.41 eV at room temperature is the technological material employed for UV laser diodes. With the advanced of growth techniques such as metal-organic chemical vapor deposition (MOCVD) and vapor phase epitaxy growth method, [25,26] high-quality GaN can be readily deposited so that GaN-based UV lasers have been realized using singlecrystal GaN film, [27,28] Fabry-Perot nanowire cavities, [29][30][31][32][33] whispering-gallery-mode cavities, [34][35][36][37][38] and vertical cavity surface emitting lasers (VCSEL). [39,40] For random scattering lasers, Fabry-Perot lasers, and whispering-gallery-mode lasers, out-ofplane directional emission lasing remains difficult to achieve. In contrast, VCSELs are designed for out-of-plane emission but require a relatively large cavity to support lasing action. BICbased lasers have the potential to realize highly directional emissions with small device sizes.Here, we demonstrate a BIC-based UV laser with directional emission and tunable emission wavelength that is fabricated on a standard GaN thin film without any etching step. A 1D periodic resist structure supporting the BIC mode was fabricated directly on the GaN thin film by a single-step electron-beam (e-beam) Optical bound states in the continuum (BICs), realizing substantial suppression of out-of-plane radiative losses, have been utilized to realize strong light confinement and optical modes with high quality-factor (Q). Lasing actions with narrow linewidths based on optical BIC modes have been demonstrated in the near-infrared and the visible ranges, but BIC-based lasers in the ultraviolet (UV) region have not been reported. As light sources possessing wavelengths at the UV scale are esse...

Solution‐Processed Perovskite Quantum Dot Quasi‐BIC Laser from Miniaturized Low‐Lateral‐Loss Cavity

“…Note that the minimum device size that exhibits lasing is 10 × 10 μm 2 for CsPbBr 3 QD cavity-supported BIC lasers, which is the smallest BIC laser among the BIC lasers based on solution-processed gain media and also comparable with the non-solution-processed BIC lasers (Table 1). [2,[4][5][6][7]12,15,[40][41][42][43][44][45][48][49][50][51][52][53][54][55][56] To further investigate the isolated cavity effect, simulated nearfield distributions for the CsPbBr 3 QD slab waveguide-BIC laser and CsPbBr 3 QD cavity-supported BIC laser are presented in Figure 5a. In this case, TiO 2 nanocylinders surrounding the QD cavity are taken into account to match the real case.…”

Lasers Based on Periodic and Quasiperiodic Planar Feedback Cavities: Designs, Principle, and Potential Applications

“…Wavelength-scale lasers, with low power consumption in high-Q BIC cavities minimizing radiative losses, offer potential for efficient active nanophotonic devices and incorporate unique cavity designs to control optical properties [49,164]. Several groups are engineering intriguing features of BICs in 1D and 2D periodic microcavities and have realized multibeam, tunable emission wavelength, multiwavelength, and even directional lasing by optimizing cavity parameters [178][179][180][181][182]. In 2018, Ha et al presented a directional BIC laser using gallium arsenide nanopillar arrays (100 nm diameter, 250 nm height), supporting vertical and in-plane dipole modes.…”

Nonvolatile and reconfigurable two-terminal electro-optic duplex memristor based on III-nitride semiconductors

“…Hence, it is necessary to construct a photosensitive AlScN memristor for in-memory sensing and computing. As a representative of the third generation semiconductors, GaN presents excellent photoelectric characteristics such as direct band-gap, strong ultraviolet absorption, and high carrier mobility, and is widely applied to detection, lightemission and optoelectronic integration [34][35][36][37][38] . Besides, as mentioned above, AlScN is easy to integrate with GaN to form hetero-structure due to their similar element composition and crystal structure.…”