Underwater Optical Wireless Communications With InGaN LEDs Grown With an Asymmetric Multiple Quantum Well for Light Emission or Detection

Abstract

InGaN light-emitting diodes (LEDs) grown with an asymmetric multiple quantum well (MQW) are proposed for use in an optical link with an avalanche photodiode (APD) based receiver. In contrast to the high photoresponse of red AlGaInP LEDs in APDs, the proposed blue LEDs provide improved light output and enhanced system bandwidth for directed line-of-sight optical links passing through a 100-cm-long water tank. This improvement is due to the nonuniform carrier distribution within the InGaN MQWs being mitigated by using a thin GaN barrier near the n-GaN to facilitate hole transport capacity. In addition, bandwidth degradation resulting from APD module saturation can also be avoided by using these blue LEDs, successfully establishing a 300 Mbit/s LED-based underwater data link. The proposed InGaN LEDs (zero bias) under illumination exhibit a peak responsivity of 0.133 at λ = 370 nm, an ultraviolet (UV)-to-visible rejection ratio of 4849 and a 3-dB cut-off frequency of 33.3 MHz. Using violet UV laser diodes and the proposed LEDs respectively as the optical transmitter and receiver, an underwater optical link (L = 100 cm) with a data transmission rate of up to 130 Mbit/s and a bit error rate of 4.2 × 10 −9 is also demonstrated.

GaN-HEMT on Si as a Robust Visible-Blind UV Detector With High Responsivity

“…Where is the surface charge, the effective variation in 2DEG can be modeled as capacitive coupling of this surface charge to the device channel as expressed in eqn. (5). Here is the effective capacitance density per unit area between the surface and the 2DEG location below the AlN layer.…”

“…ALLIUM nitride electronics has gained huge attention in recent years due to its inherent advantages of the wide band gap material and Two-Dimensional Electron Gas (2DEG) formation when an AlGaN/GaN heterojunction is grown [1,2]. High frequency power electronics, optical and sensing technology are the three main application domains of GaN based devices [3][4][5][6]. Recent years have seen an increased interest in development of UV detectors due to their increased demands in military, civil and space applications [7,8].…”

Under-Seawater Immersion β-Ga2O3 Solar-Blind Ultraviolet Imaging Photodetector with High Photo-to-Dark Current Ratio and Fast Response

“…Research on equipment for seawater detection has gained more attention with the development and utilization of marine resources. Most seawater photodetectors (PDs) focus on the visible and ultraviolet range (λ ≈ 360 nm) rather than the solar-blind ultraviolet (SBUV) detection. − However, compared with the former two light bands, solar-blind ultraviolet (λ = 200–280 nm) can provide higher spatial resolution and detection sensitivity without being affected by the sunlight background, especially suitable for the detection in harsh, remote, and water environments, which is of great significance to the research of biological security, water quality detection, and missile approach warning system. − The working conditions of seawater PDs are different from those required by solid-state devices, which determines that this kind of device must work independently and continuously without top electrodes and external power sources. − Recently, a semiconductor/electrolyte-structured photodetector suitable for seawater detection has attracted considerable academic interest. − Compared with traditional solid-state PDs, the semiconductor/electrolyte-structured photodetector can directly use seawater as an electrolyte to work normally underwater and can also skip the waterproof packaging process during manufacturing and operation. Thus, we think it can be widely and conveniently applied in the field of under-seawater detection.…”

FLANN-based inter-code crosstalk suppression study for underwater laser communication

“…Underwater optical wireless communication (UWOC) channels refer to water bodies where lasers are used as the information carrier, with clean water or seawater serving as the transmission medium. UWOC has found extensive applications in target detection, feature extraction, and proximity communication, effectively bridging the performance gap in hydroacoustic communication [1][2][3][4]. Nonetheless, this communication method is susceptible to multipath effects caused by the time-dispersive nature of the channel.…”