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AlGaAs is a promising integrated nonlinear photonics material with enormous optical nonlinearity and high refractive index. Nevertheless, presently AlGaAs microring resonators exhibiting high-quality factors and tight optical confinement rely predominantly on wafer bonding techniques, which entail an intricate fabrication process. Here, we present suspended AlGaAs waveguides and resonators as a viable platform for high efficiency integrated nonlinear photonics. The suspended microring resonator formed by combined plasma dry etching and chemical wet etching exhibits an intrinsic quality factor Q of 2.1 × 10 6 , corresponding to an optical loss of 0.28 dB/cm, and Kerr comb generation with milliwatt level threshold is recorded. The proposed scheme can be implemented with a relatively simple fabrication process, as it eliminates the need for wafer bonding. Without the hinderance of SiO 2 or Al 2 O 3 claddings, the air-clad suspended AlGaAs platform lends itself directly to applications in the mid-infrared region. Our demonstration opens up a prospect for employing AlGaAs devices in integrated nonlinear photonics. [ABSTRACT FROM AUTHOR]

The size-dependent emission wavelength shift of micro-scale light emitting diodes (micro-LEDs) has been frequently reported in recent publications, but its underlying physical mechanism has not yet been thoroughly elucidated. Here, we fabricate and characterize the red, green, and blue InGaN micro-LED mesas with different diameters down to 1 μm. As the size decreases, all the samples of different colors show an inverted V-shaped photoluminescence wavelength variation trend, first a red shift and then a blue shift, and the shifting range is larger for samples with longer wavelengths. Micro-Raman spectrum confirms that the stress was significantly released after scaling down the size from epitaxial wafer to 1 μm. The theoretical simulations show that the red and blue shifts are, respectively, attributed to the bandgap narrowing and the weakening of the quantum-confined Stark effect caused by strain relaxation, which dominate successively. [ABSTRACT FROM AUTHOR]

Semipolar {101¯1} InGaN quantum dots (QDs) formed on GaN V‐shaped pits by metal–organic vapor‐phase epitaxy (MOVPE) with a growth interruption method are reported. The 3D GaN V‐pit structures are directly grown on a patterned sapphire substrate (PSS). By adjusting the pattern arrangement direction on the substrate, it is observed in the scanning electron microscopy (SEM) image that elliptical QDs are formed on the {101¯1} semipolar sidewalls of the V‐pits with a density of about 5 × 1010 cm−2. The emission wavelength of semipolar InGaN QDs is confirmed by cathodoluminescence (CL). The gradient distribution of In composition and QD size are observed along the sidewall of the V‐pits. On this basis, a three‐period semipolar InGaN QD sample is prepared. For the temperature‐dependent photoluminescence (TDPL) test, the prominent peak of the sample shows a blueshift with the increase in temperature and reaches the green band (≈523 nm) at room temperature (RT). According to time‐resolved photoluminescence (TRPL) decay curves, a carrier lifetime of 329.3 ps fit by the stretched exponential model is obtained at RT. Compared with c‐plane QDs with the same growth method, the semipolar QDs have a shorter radiative recombination lifetime due to suppressed polarization electric field. [ABSTRACT FROM AUTHOR]