Given the high demand for miniaturized optoelectronic circuits, plasmonic devices with the capability of generating coherent radiation at deep subwavelength scales have attracted great interest for ...diverse applications such as nanoantennas, single photon sources, and nanosensors. However, the design of such lasing devices remains a challenging issue because of the long structure requirements for producing strong radiation feedback. Here, a plasmonic laser made by using a nanoscale hyperbolic metamaterial cube, called hyperbolic metacavity, on a multiple quantum‐well (MQW), deep‐ultraviolet emitter is presented. The specifically designed metacavity merges plasmon resonant modes within the cube and provides a unique resonant radiation feedback to the MQW. This unique plasmon field allows the dipoles of the MQW with various orientations into radiative emission, achieving enhancement of spontaneous emission rate by a factor of 33 and of quantum efficiency by a factor of 2.5, which is beneficial for coherent laser action. The hyperbolic metacavity laser shows a clear clamping of spontaneous emission above the threshold, which demonstrates a near complete radiation coupling of the MQW with the metacavity. This approach shown here can greatly simplify the requirements of plasmonic nanolaser with a long plasmonic structure, and the metacavity effect can be extended to many other material systems.
Deep‐ultraviolet laser action is demonstrated using a specific hyperbolic metacavity. This metacavity provides a tight mode confinement (i.e., ultrasmall mode volume) and thus increases the light–matter interactions. Meanwhile, a unique radiation flow is induced to assist the consolidation of plasmon resonances within the metacavity, which provides strong radiation feedback for laser operation.
A White Random Laser Chang, Shu-Wei; Liao, Wei-Cheng; Liao, Yu-Ming ...
Scientific reports,
02/2018, Volume:
8, Issue:
1
Journal Article
Peer reviewed
Open access
Random laser with intrinsically uncomplicated fabrication processes, high spectral radiance, angle-free emission, and conformal onto freeform surfaces is in principle ideal for a variety of ...applications, ranging from lighting to identification systems. In this work, a white random laser (White-RL) with high-purity and high-stability is designed, fabricated, and demonstrated via the cost-effective materials (e.g., organic laser dyes) and simple methods (e.g., all-solution process and self-assembled structures). Notably, the wavelength, linewidth, and intensity of White-RL are nearly isotropic, nevertheless hard to be achieved in any conventional laser systems. Dynamically fine-tuning colour over a broad visible range is also feasible by on-chip integration of three free-standing monochromatic laser films with selective pumping scheme and appropriate colour balance. With these schematics, White-RL shows great potential and high application values in high-brightness illumination, full-field imaging, full-colour displays, visible-colour communications, and medical biosensing.
Despite the demands of growth, the development of deep-ultraviolet (UV) light-emitting diodes (LEDs) still suffers from the fundamental limits of material defects and the anisotropic optical property ...of AlGaN multiple quantum-wells (MQWs), resulting in an extremely low emission output. Here, we present a novel approach to address this issue by using a nanoscale hyperbolic metacavity on the deep-UV LED, where the resonant modes of metacavity are excited. An intense plasmon field is consequently feedback to the MQW. This strong resonant mode feedback allows the dipoles of MQW recombine directionally, thereby achieving enhancements of radiative emission rate by a factor of 160 and quantum efficiency by a factor of 3.5. It also shows the capability of metacavity in tailoring the direction of light emission, leading to a 520% increase in total emission intensity and 148% increase in emission extraction. A small divergence angle of 65° of LEDs is therefore demonstrated. Our study clearly shows that the use of metacavity is a promising candidate for the highly-desired efficiency and directivity deep-UV applications, and the metacavity effect can be extended to other nanoscale devices, such as nanolaser, single photon source, nano-biosensor, and nano-antenna.
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•In recent years, nitride-based LEDs have shown the superiority in low energy consumption and environmental healthy for new lights, optical communication, and display.•However, in deep-UV wavelength, nitride-based LED has not completely fulfilled the promise as energy-saving alternative due to the extremely low quantum efficiency. Here, we provide a novel approach to improve the issue by using a hyperbolic metacavity on a deep-UV LED.•The metacavity exhibits several excellent features, including a 160-fold enhancement in radiative emission rate and 3.5-fold enhancement in quantum efficiency. It also shows a 520% increase in total emission intensity and 148% increase in light extraction.•The integration of AlGaN and metacavity not only suppresses the energy consumption by defects to achieve a highly efficiency deep-UV LED, but also effectively directs the emission direction to avoid energy being wasted in LED structure.•An obviously tailoring light effect of metacavity is first time observed.This demonstrates a small divergence angle of 65° of deep-UV LED. Our study also suggests that metacavity can be employed for other nanoscale devices (nanolaser, single photon source, nanobiosensor, and nanoantenna).
Transient technology is deemed as a paramount breakthrough for its particular functionality that can be implemented at a specific time and then totally dissolved. Hyperbolic metamaterials (HMMs) with ...high wave-vector modes for negative refraction or with high photonic density of states to robustly enhance the quantum transformation efficiency represent one of the emerging key elements for generating not-yet realized optoelectronics devices. However, HMMs has not been explored for implementing in transient technology. Here we show the first attempt to integrate transient technology with HMMs, i.e., transient HMMs, composed of multilayers of water-soluble and bio-compatible polymer and metal. We demonstrate that our newly designed transient HMMs can also possess high-k modes and high photonic density of states, which enables to dramatically enhance the light emitter covered on top of HMMs. We show that these transient HMMs devices loss their functionalities after immersing into deionized water within 5 min. Moreover, when the transient HMMs are integrated with a flexible substrate, the device exhibits an excellent mechanical stability for more than 3000 bending cycles. We anticipate that the transient HMMs developed here can serve as a versatile platform to advance transient technology for a wide range of application, including solid state lighting, optical communication, and wearable optoelectronic devices, etc.
Abstract
Rollable photonic devices that can adapt to freeform surfaces with reduced dimensions while maintaining their original functionalities are highly desirable. Among photonic devices, ...metamaterials with hyperbolic dispersion in momentum space, defined as hyperbolic metamaterial (HMM), possess a large photonic density of states that has been proven to boost light-matter interaction. However, these devices are mainly developed on rigid substrates, restricting their functionalities. Here, we present the attempt to integrate flexible and rollable HMMs consisting of polymer and metal multilayers on paper substrate. Quite interestingly, this design enables to exhibit high photonic density of states and scattering efficiency to enhance stimulated emission and induce pronounced laser action. The flexible and rollable HMM structure remains well its functionalities on freeform surfaces with curvature radius of 1 mm, and can withstand repeated bending without performance degradation. The intensity of laser action is enhanced by 3.5 times as compared to the flat surface. We anticipate that this flexible and rollable HMM structure can serve as a diverse platform for flexible photonic technologies, such as light-emitting devices, wearable optoelectronics, and optical communication.
The method to construct the three-dimensional (3D) ordered nanostructure of ZnO for improving its performance has attracted considerable attention and remains a challenging issue, which has ...theoretical and practical implications for nanoscale applications such as optoelectronics and gas sensors. Herein, we demonstrate a straightforward chemical vapor deposition (CVD) technique for the epitaxial growth of 3D cross-linked comb-like ZnO arrays on r-plane sapphire substrates. The morphological, structural, and optical properties of the as-synthesized samples were examined using X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscopy, Raman spectroscopy, UV–vis spectroscopy, and photoluminescence spectroscopy. A cooperative growth mechanism is suggested to construct 3D cross-linked comb-like ZnO arrays: The supersaturated alloy forms a backbone of oblique nanosails along 101̅0 by the Au-assisted catalytic vapor–liquid–solid (VLS) growth mechanism and the inevitable vapor–solid (VS) lateral extension growth process; simultaneously discrete nanoteeth are grown along the unilateral c-direction 0001 by the Zn self-catalytic VLS mechanism, culminating in a 3D cross-linked array of comb-like ZnO. The development of such a unique 3D cross-linked array allows the exploration of performance in gas-sensitive devices, optoelectronics, and quantum electrical information applications.
InGaN films with 33% and 60% indium contents were deposited by pulsed laser deposition (PLD) at a low growth temperature of 300 °C. The films were then annealed at 500-800 °C in the non-vacuum ...furnace for 15 min with an addition of N(2) atmosphere. X-ray diffraction results indicate that the indium contents in these two films were raised to 41% and 63%, respectively, after annealing in furnace. In(2)O(3) phase was formed on InGaN surface during the annealing process, which can be clearly observed by the measurements of auger electron spectroscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. Due to the obstruction of indium out-diffusion by forming In(2)O(3) on surface, it leads to the efficient increment in indium content of InGaN layer. In addition, the surface roughness was greatly improved by removing In(2)O(3) with the etching treatment in HCl solution. Micro-photoluminescence measurement was performed to analyze the emission property of InGaN layer. For the as-grown InGaN with 33% indium content, the emission wavelength was gradually shifted from 552 to 618 nm with increasing the annealing temperature to 800 °C. It reveals the InGaN films have high potential in optoelectronic applications.
Thermal stability on the structural and optical properties of high indium content InGaN films grown using pulsed laser deposition (PLD) was investigated through long-duration and high-temperature ...annealing. X-ray diffraction and cathode- luminescence measurements of the 33% indium InGaN revealed no differences in the line-shape and peak position even after annealing at 800°C for 95 min; similar structural stability was found for the 60% samples after annealing for 75 min. The higher thermal stability is attributed to nanoscale InN domains with different orientations create mixed-polarity InGaN/InN interfaces, resulting in higher activation energies at interfaces and increasing the thermal stability of the material. Furthermore, the InGaN films were subjected to metalorganic chemical vapor deposition treatment to regrow a GaN layer; results are promising for the development of high thermal stability InGaN films using the PLD technique.
A high-quality GaN-based vertical light-emitting diode (LED) was successfully fabricated and transferred to an electroplated Cu substrate using strip-patterned silicon dioxide (SiO2) as a sacrificial ...layer in a chemical lift-off (CLO) process. The SiO2 strip patterns not only provide the sacrificial structure during the detachment process, but also improve the quality of GaN epilayers through epitaxial lateral overgrowth. Compared with conventional LEDs, the CLO-LEDs have a higher output power and a lower forward voltage. The CLO-LED has a decrease in forward voltage of 0.42 V (at 20 mA) as compared with the conventional LED. In addition, at a drive current of 350 mA, the output power of CLO-LEDs is enhanced ~ 2.2 fold, compared with that of conventional LEDs.
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