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Inserting multiple quantum wells (MQWs) into a p–n junction, III-nitride MQW diodes can separately function as a light transmitter, modulator, and receiver under different bias conditions. Owing to the spectral overlap between the emission and responsivity spectra, the emitted light from the transmitter is able to be modulated and detected by the modulator and receiver, which have identical MQW structures. Here, we develop a compatible fabrication process to monolithically integrate an III-nitride light transmitter, waveguides, Y-splitter, modulators, Y-combiner, and receiver into a tiny chip. An on-chip 405 nm light communication system is established and exhibits a transmission rate of 260 Mbps in the non-return-to-zero on-off keying scheme. The results pave a feasible route to develop sophisticated monolithic photonic circuit on an III-nitride-on-silicon platform. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) is a key technology for 6G. Here, we propose, fabricate, and characterize a vertical-structure light-emitting diode (VSLED) to manage the dilemma of both power and speed for VLCs. Ultrathin VSLED architecture offers the unique features of decreasing the RC time constant for increasing modulation bandwidth and reducing confined optical modes inside the diode for enhancing light extraction. A 580-nm-thick VSLED with a dominant emission wavelength of 427.8 nm is implemented on a 2-in. metal-based bonded III-nitride-on-silicon wafer. Based on a bit-loading discrete multitone modulation scheme, we establish a visible light communication system using 1 × 1 mm2 VSLED, which can achieve a data transmission rate of 608 Mbps at a baud rate of 200 MBaud. [ABSTRACT FROM AUTHOR]

We demonstrate a vertical AlGaN DUV LED with an emission wavelength of 272 nm and submicron thickness. The device epilayers' thickness is reduced to ∼670 nm by a combination of wafer bonding and thinning techniques, and this results in the thinnest vertical DUV LED reported to date. A light-emitting surface with a root mean square value of 74.7 nm is also induced by the thinning process without any other surface-roughing treatments. An n-contact electrode with a mesh geometry is adopted to expose the emission region, while the bottom metal electrode functions as a reflector to reflect downward-propagating light in an upward direction. [ABSTRACT FROM AUTHOR]

The integration of III‐nitride electronics and photonics is of great interest toward future computing systems with low power consumption. Multifunctioning multiple quantum well (MQW) diodes can address the challenging issue for on‐chip integration of a light source, which is a key component to drive the photonic circuits. Herein, a transmitter, waveguide, modulator, and receiver are monolithically integrated on a III‐nitride‐on‐silicon platform to perform light emission, transmission, modulation, and detection simultaneously. Both the receiver and modulator exhibit sufficient sensitivity to optical signals from the transmitter, which has an identical InGaN/AlGaN multiple quantum well (MQW) structure because the III‐nitride diode provides spectral overlap between the emission and absorption spectra. On‐chip data communication among these optical components is achieved using light, and the effective wavelength range is from 365 to 385 nm, in which multifunctional devices can be operated. [ABSTRACT FROM AUTHOR]

A floating GaN Penrose microcavity is fabricated by standard micro-and-nano fabrication techniques. Ultraviolet whispering gallery mode and Fabry-Pérot (F-P) mode lasings are obtained under optical pumping conditions at room temperature. The lasing characteristics of the emission intensity, the threshold and the resonance mechanism are presented. It should be noted that the Fabry-Pérot mode lasing could be converged due to the focusing effect of half-ellipse shape mirrors. Analysis of the lasing mode number is also given to confirm the lasing resonance mechanism. A commercial two-dimensional finite difference time domain simulation software is used to study near-field distribution and far-field distribution of a Penrose microcavity, presenting the resonance mechanism of two types of lasing modes. It is significant for improving devices' coupling efficiency, as well as the high-density integrated optoelectronics system. [ABSTRACT FROM AUTHOR]

Multifunctional flow sensors are important components of smart systems when considering the Internet of things. In this work, a membrane light‐emitting diode sensor (LED‐S) is examined by utilizing the signals produced from the piezoelectric and heat dissipation effects for real‐time flow rate detection. In association with silicon removal and backside III‐nitride thinning, an InGaN/GaN LED is fabricated on a 1.58 mm diameter suspended membrane. In response to a flow rate change, the suspended membrane is deformed and the accumulated heat within the device is dissipated, which leads to an induced current. Consequently, the membrane LED can create light emission and flow detection simultaneously. The light emission is modulated for the implementation of visible light communication, which can connect the LED‐S to the internet. These results demonstrate that the LED‐S has great potential to be integrated into a multicomponent system for flow sensing, pressure sensing, and environment monitoring. [ABSTRACT FROM AUTHOR]

We propose and fabricate a dual-emitter light-induced neuromorphic device composed of two light-induced devices with a common collector and base. Two InGaN multiple-quantum-well diodes (MQW-diodes) are used as the emitters to generate light, and one InGaN MQW-diode is used as the common collector to absorb the emitted light. When the presynaptic voltages are synchronously applied to the two emitters, the collector demonstrates an adding together of the excitatory postsynaptic voltage (EPSV). The width and period of the two input signals constitute the code to generate spatial summation and recognition effects at the same time. Experimental results confirm that temporal summation caused by the repetitive-pulse facilitation could significantly strengthen the spatial summation effect due to the adding together behavior when the repetitive stimulations are applied to the two emitters in rapid succession. Particularly, the resonant summation effect occurs at the cosummation region when the two repetitive-pulse signals have a resonant period, which offers a more sophisticated spatiotemporal EPSV summation function for the dual-emitter neuromorphic device. [ABSTRACT FROM AUTHOR]

The InGaN/GaN multiple-quantum-well (MQW) diode has selectable functionalities with emission and detection in the visible region due to the MQW-based p-n junction structure, which is employed to achieve on-chip optocoupling. Here, we propose to fabricate a suspended InGaN/GaN MQW diode on an III-nitride-on-silicon platform by a combination of silicon removal and III-nitride backside etching. Spatial simultaneous light-emitting light-detecting functionality, in which the detected light comes from an external light source, is experimentally demonstrated, endowing the MQW diode with the capability of contributing to intelligent displays as well as full-duplex visible light communication. As a transmitter, the InGaN/GaN MQW diode demonstrates out-of-plane data transmission at 120 Mb/s using visible light. [ABSTRACT FROM AUTHOR]

The key issue preventing RGBW LCDs from wide application in the display market was probably the absence of a proper RGB-to-RGBW mapping algorithm with no color-distortion. In this paper, a new RGBW mapping algorithm was designed so that the hue and saturation remain unchanged from the original color. Perception experiment for new algorithm based on our intellectual energy-saving technology (IEST) product indicated that it has superior performance upon conventional RGBW and almost indiscernible to common RGB. [ABSTRACT FROM AUTHOR]

In this letter, we build an on-chip photonic integration system on a GaN-on-silicon platform. Using silicon removal and back wafer etching techniques, two suspended InGaN/GaN multiple-quantum-well diodes (MQWDs), which are connected by suspended waveguides, are fabricated as a transmitter and a receiver, respectively, in the on-chip photonic integration system. The 100- \mu \textm -long, 2- \mu \textm -high, and 3- \mu \textm -wide suspended waveguides are adopted for light coupling and transmission between the transmitter and the receiver. When the transmitter emits light, the InGaN/GaN MQWD simultaneously exhibits an extraordinary light detection mechanism in which the light-induced electron-hole pairs are greatly increased and can be rapidly cancelled by the injection current. The on-chip photonic integration system experimentally demonstrates the significantly improved 3-dB bandwidth and data transport performances when the receiver operates under the simultaneous light emission and detection mode. [ABSTRACT FROM PUBLISHER]

We propose and fabricate a comb-like light-induced synaptic transistor composed of two InGaN/GaN multiple-quantum-well diodes (MQWDs) with a common base. One InGaN/GaN MQWD is used as an emitter of light, and another InGaN/GaN MQWD is used as a collector. When a presynaptic voltage is applied to the emitter to generate light, the collector absorbs the emitted light and demonstrates an excitatory postsynaptic voltage (EPSV). Saturated EPSV behavior occurs at the collector when multiple pulse signals are continuously applied to the emitter. The saturated EPSV value is increased and the saturated pulse number is reduced as the amplitude of the applied pulse signal increases. Experimental results indicate that continuous stimuli with a high pulse intensity will greatly improve the memory effect during the learning process. [ABSTRACT FROM PUBLISHER]

We propose and fabricate a light induced transistor using a combination of two multiple-quantum-well diodes (MQWDs) with a common n-electrode as the base. Both silicon removal and back wafer etching are conducted to obtain a suspended device architecture. The InGaN/GaN MQWD detects light only when the bias voltage is below the turn-ON voltage and can simultaneously achieve light emission and detection when it turns ON. Therefore, the light induced transistor operates with two distinct light detection modes. The excitatory postsynaptic voltages (EPSVs) are distinct due to the different decay times. Paired-pulse facilitation is experimentally demonstrated to mimic the synaptic plasticity behavior. The EPSV amplitudes are dependent on the pulse interval and pulse number. [ABSTRACT FROM AUTHOR]

With a three-dimensional semiclassical ensemble simulation, we comprehensively analyse the underlying dynamics of the photoelectron energy plateau (with an energy ranging from 2Up to 10Up, Up is the ponderomotive energy) from the single ionization of atoms in strong linearly polarized laser fields. We study the initial tunnelling coordinates at the tunnel exit (tunnelling phase and initial transverse momentum) of those high-energy photoelectrons. The rescattering process is very sensitive to the initial transverse momentum at the tunnel exit. We further identify the significant role of the long-range Coulomb potential on the rescattering process, which is usually ignored for those high-energy plateau electrons. Depending on the initial tunnelling coordinates, multiple forward scattering plus a hard collision has a significant contribution to the yield of the high-energy photoelectrons. By analysing the tunnelling coordinates of rescattering electrons, this provides sophisticated information for other related rescattering processes, i.e., high-harmonic generation and nonsequential double ionization. [ABSTRACT FROM AUTHOR]

InGaN/GaN multiple quantum well (MQW) diodes perform multiple functions, such as optical emission, modulation and reception. In particular, the partially overlapping spectral region between the electroluminescence (EL) and responsivity spectra of each diode results in each diode being able to sense light from another diode of the same MQW structure. Here, we present a noncontact, optical proximity sensing system by integrating an MQW-based light transmitter and detector into a tiny GaN-on-sapphire chip. Changes in the external environment modulate the light emitted from the transmitter. Reflected light is received by the on-chip MQW detector, wherein the carried external modulation information is converted into electrical signals that can be extracted. The maximum detection proximity is approximately 17 mm, and the displacement detection accuracy is within 1 mm. Based on the detection of distance, we extend the application of the sensor to vibration and pressure detection. This monolithic integration design can replace external discrete light transmitter and detector systems to miniaturize reflective sensor architectures, enabling the development of novel optical sensors.

Nitride-based semiconductor materials inherently have the intriguing functionalities of emission and photodetection. In particular, InGaN/GaN multiple-quantum-well (MQW) diodes exhibit dual light-harvesting and light-emitting modes of operation. Here a multifunctional system is proposed to integrate MQW diodes within a single chip with enhanced functionalities toward diverse applications of the Internet of Things (IoT). When we shine light on the MQW diodes, the absorbed photons can produce electron-hole pairs to charge an external capacitor. The energy of the ambient light is converted into electrical energy, which in turn powers the same MQW diode for lighting. The electrical energy within the capacitor is finally converted into the energy of the emitted light. Therefore, InGaN/GaN MQW diodes can be made to harvest energy from ambient light sources for IoT applications from a self-powered light source to intelligent terminal charging system.

In the brain, each postsynaptic neuron interconnects many presynaptic neurons and performs functions that are related to summation and recognition as well as correlation. Based on a convolution operation and nonlinear distortion function, we propose a mathematical model to explore the elementary synaptic mechanism. A four-emitter light-induced artificial synapse is implemented on an III-nitride-on-silicon platform to validate the device concept for emulating the synaptic behaviors of a biological synapse with multiple presynaptic inputs. In addition to a progressive increase in the amplitude of successive spatiotemporal excitatory postsynaptic voltages, the differences in the stimulations are remembered for signal recognition. When repetitive stimulations are simultaneously applied and last over a long period of time, resonant spatiotemporal correlation occurs because an association is formed between the presynaptic stimulations. Four resonant spatiotemporal correlations of each triple-stimulation combination are experimentally demonstrated and agree well with the simulation results. The repetitive stimulation combinations with prime number-based periods inherently exhibit the maximum capacity of resonant spatiotemporal correlation. Our work offers a new approach to building artificial synapse networks.

The multiple functionalities of III-nitride semiconductors enable the integration with different components into a multicomponent system with enhanced functions. Here, we propose to fabricate and characterize a monolithic InGaN photonic circuit of a transmitter, waveguide, and receiver on an III-nitride-on-silicon platform. Both the transmitter and the receiver, sharing identical InGaN/GaN multiple-quantum-well structures and fabrication procedures, work to emit light and detect light independently. The 8 μm wide and 200 μm long InGaN waveguide couples the modulated light from the transmitter and sends the guided light to the receiver, leading to the formation of an in-plane light transmission system. The induced photocurrent at the receiver is highly sensitive to the light output of the transmitter. Multi-dimensional light transmissions are experimentally demonstrated at 200 Mb/s. These multifunctional photonic circuits open feasible approaches to the development of III-nitride multicomponent systems with integrated functions for comprehensive applications in the visible region.

We propose, fabricate and demonstrate on-chip photonic integration of suspended InGaN/GaN multiple quantum wells (MQWs) devices on the GaN-on-silicon platform. Both silicon removal and back wafer etching are conducted to obtain membrane-type devices, and suspended waveguides are used for the connection between p-n junction InGaN/GaN MQWs devices. As an in-plane data transmission system, the middle p-n junction InGaN/GaN MQWs device is used as a light emitting diode (LED) to deliver signals by modulating the intensity of the emitted light, and the other two devices act as photodetectors (PDs) to sense the light guided by the suspended waveguide and convert the photons into electrons, achieving 1 × 2 in-plane information transmission via visible light. Correspondingly, the three devices can function as independent PDs to realize multiple receivers for free space visible light communication. Further, the on-chip photonic platform can be used as an active electro-optical sensing system when the middle device acts as a PD and the other two devices serve as LEDs. The experimental results show that the auxiliary LED sources can enhance the amplitude of the induced photocurrent.