Effect of substrates on lasing properties of GaN transferable membranes

Qin, Feifei; Zhu, Qiuxiang; Zhang, Yanfang; Wang, Ru; Wang, Xiaoxuan; Zhou, Mengyao; Yang, Ying

doi:10.1016/j.optmat.2021.111663

Cited by 6 publications

(4 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since there may be raindrops in the apple leaf images collected in the field environment, we preprocessed the apple leaf images collected in real time. We first judged whether there were raindrops in the input detection pictures, used GAN network to reduce the noise of the images, and then detect the disease on the images after noise reduction [ 37 ].…”

Section: Methodsmentioning

confidence: 99%

Apple-Net: A Model Based on Improved YOLOv5 to Detect the Apple Leaf Diseases

Zhu

et al. 2022

Plants

View full text Add to dashboard Cite

Effective identification of apple leaf diseases can reduce pesticide spraying and improve apple fruit yield, which is significant to agriculture. However, the existing apple leaf disease detection models lack consideration of disease diversity and accuracy, which hinders the application of intelligent agriculture in the apple industry. In this paper, we explore an accurate and robust detection model for apple leaf disease called Apple-Net, improving the conventional YOLOv5 network by adding the Feature Enhancement Module (FEM) and Coordinate Attention (CA) methods. The combination of the feature pyramid and pan in YOLOv5 can obtain richer semantic information and enhance the semantic information of low-level feature maps but lacks the output of multi-scale information. Thus, the FEM was adopted to improve the output of multi-scale information, and the CA was used to improve the detection efficiency. The experimental results show that Apple-Net achieves a higher mAP@0.5 (95.9%) and precision (93.1%) than four classic target detection models, thus proving that Apple-Net achieves more competitive results on apple leaf disease identification.

show abstract

Section: Methodsmentioning

confidence: 99%

Apple-Net: A Model Based on Improved YOLOv5 to Detect the Apple Leaf Diseases

Zhu

et al. 2022

Plants

View full text Add to dashboard Cite

show abstract

“…One is in the ultraviolet region, with a peak near 370 nm, belonging to nearband-edge emission of GaN. [37] The other is in the blue region with a peak near 430 nm, belonging to the emission of the QW layers. A clear PL shift is observed at high temperature.…”

Section: Structural and Optical Properties Of Gan Beam Cavitymentioning

confidence: 99%

Optically pumped wavelength-tunable lasing from a GaN beam cavity with an integrated Joule heater pivoted on Si

et al. 2023

Self Cite

View full text Add to dashboard Cite

Dynamically tunable laser sources are highly promising for realizing visionary concepts of integrated photonic circuits and other applications. In this paper, PN junction heater integrated gallium nitride-based laser on Si is fabricated. The photoluminescence (PL) properties of the GaN beam cavity are controlled by temperature, and the Joule heater provides electrically driven regulation of temperature. These two features of the cavity make it possible to realize convenient tuning of the lasing properties. The multi-functional GaN beam cavity achieves optically pumped lasing with a single mode near 362.4 nm with high Q factor of 1394. The temperature of this device increases by up 0 ℃ to 5 ℃ under the Joule heating effect. Then, electrical control of the lasing mode is demonstrated. The lasing resonant peak shows a continuous redshift of about 0.5 nm. And it also exhibits dynamic switching of its lasing mode. The lasing modulation can be ascribed to temperature-induced reduction of the bandgap. Our work may be of benefit for external optical modulation for future chip-based optoelectronic devices.

show abstract

“…Nanolasing has attracted increasing attention due to the widespread applications in miniaturized lasing light sources, chemical and biological sensing, photonic integration, etc. − Due to the advantages of the stable physical and chemical properties, wide direct band gap, and high dielectric contrast with air, gallium nitride (GaN) has been widely chosen to fabricate optoelectronic devices such as lasers. − Since the first stimulated emission from a GaN film was reported at room temperature in the 1990s, a series of GaN-based lasing has been implemented in micro/nanostructures to facilitate micro/nanointegration of optoelectronic circuits. − Low-dimensional GaN micro/nanostructures, such as nanowires, nanoroads, and nanobelts, can be used as the gain media and optical cavity directly and also have higher photon confinement to improve radiative recombination due to the small size effect, the dielectric confinement effect, etc. However, relevant studies on GaN nanobelt-based lasing are missing.…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet Lasing Using Individual GaN Nanobelts

Dong

Wang

Yang

et al. 2023

ACS Appl. Nano Mater.

Self Cite

View full text Add to dashboard Cite

It is crucial to realize gallium nitride (GaN) ultraviolet nanolasing to cater the needs of on-chip integration and optical interconnection, quantum information processing, and high-density storage. The key challenge is preparing freestanding high-crystal quality GaN micro/nanostructures with a controllable structure to realize single-mode ultraviolet nanolasing with a low threshold. Here, a freestanding GaN nanobelt is prepared using the graphically epitaxial lift-off technique, and multimode ultraviolet Fabry–Pérot lasing is obtained from a single GaN nanobelt on a 300 nm SiO2 spacer layer on a Si substrate. To further reduce optical losses and improve lasing performances, anisotropic KOH polishing is chosen to construct smooth mirrors. After process optimization, the Q value of the lasing is enhanced by about fivefold and the threshold is lowered to 7.76 μW. By further increasing the KOH polishing time to decrease the size of the microcavity, single-mode ultraviolet Fabry–Pérot lasing with a Q value of 1036 has been obtained over a threshold of 9.56 μW at room temperature, due to the absence of mode competition and group velocity dispersion. Our work has provided an effective and straightforward blueprint for the realization of ultrahigh-performance single/multimode GaN-based lasing based on freestanding micro/nanostructures.

show abstract

Effect of substrates on lasing properties of GaN transferable membranes

Cited by 6 publications

References 31 publications

Apple-Net: A Model Based on Improved YOLOv5 to Detect the Apple Leaf Diseases

Apple-Net: A Model Based on Improved YOLOv5 to Detect the Apple Leaf Diseases

Optically pumped wavelength-tunable lasing from a GaN beam cavity with an integrated Joule heater pivoted on Si

Ultraviolet Lasing Using Individual GaN Nanobelts

Contact Info

Product

Resources

About