Full-duplex wireless light communication using green laser diodes.

The integration of wireless light communication into a wireless fidelity (Wi-Fi) module and gateway enables real-time integrated communication networks that satisfy practical application demands. In particular, wireless green light communication tools can operate underwater and in free-space environments. Here, we design, fabricate, and characterize a full-duplex light communication system using green laser diodes (LDs). Operating within the transmission control protocol/internet protocol (TCP/IP), full-duplex wireless data transmission is confirmed in underwater and free-space environments at a communication rate of 10 Mbps. Through connections to a Wi-Fi module and gateway, the system is accessed by the network via the TCP/IPv4 internet scheme, and real-time video transmission is demonstrated.

All-light communication network for space-air-sea integrated interconnection.

Space-air-sea communication networks are of great interest to meet the demand for close and seamless connections between space, land, and ocean environments. Wireless light communication can expand network coverage from land to the sky and even the ocean while offering enhanced anti-interference capabilities. Here, we propose and establish an all-light communication network (ALCN) for space-air-sea integrated interconnection, which merges underwater blue light communication, wireless white light communication, solar-blind deep ultraviolet light communication and laser diode-based space communication. Ethernet switches and the Transmission Control Protocol are used for space-air-sea light interconnection. Experimental results show that the ALCN supports wired and wireless device access simultaneously. Bidirectional data transmission between network nodes is demonstrated, with a maximum packet loss ratio of 5.80% and a transmission delay below 74 ms. The proposed ALCN provides a promising scheme for future space-air-sea interconnections towards multiterminal, multiservice applications.

Collinear optical links based on a GaN-integrated chip for fiber-optic acoustic detection.

This Letter reports a collinear optical interconnect architecture for acoustic sensing via a monolithic integrated GaN optoelectronic chip. The chip is designed with a ring-shaped photodiode (PD) surrounding a light-emitting diode (LED) of a spectral range from 420-530 nm. The axisymmetric structure helps the coaxial propagation of light transmission and reception. By placing this multiple-quantum wells (MQW)-based device and a piece of aluminum-coated polyethylene terephthalate (Al/PET) film on fiber ends, an ultra-compact acoustic sensing system is built. The sound vibrations can be simply detected by direct measurement of the diaphragm deformation-induced power change. An average signal noise ratio (SNR) of 40 dB and a maximum sensitivity of 82 mV/Pa are obtained when the acoustic vibration frequency changes from 400 Hz to 3.2 kHz. This work provides a feasible solution to miniaturize the sensing system footprint and reduce the cost.

Optical wireless communication using a flexible and waterproof perovskite color converter.

In this Letter, the CH3NH3PbBr3 nanocrystals (NCs) are embedded into the interstices of the fluorine (polyvinyl fluoride/polyvinylidene fluoride, PVF/PVDF) matrix on polyethylene terephthalate (PET) substrate to introduce new advantages, such as being flexible and waterproof, while maintaining the high optical performance of perovskites. The sample's photoluminescence (PL) spectra under 325 nm laser is a green emission peaked at 537 nm with full width at half maximum (FWHM) of about 21.2 nm and a fast PL decay time. As a color converter, it shows high optical absorption and can transform light from solar-blind ultraviolet to a blue region into a green region in air, water, and bending conditions. While excited by a 270 nm ultraviolet light-emitting diode (LED), the system's observed -3 dB bandwidth with the color converter is near 4.4 MHz in air and water conditions with well-eye diagrams at a data rate of 30 Mbps. Finally, we demonstrate an audio transmission application with an ultraviolet light source, a color conversion layer, and a low-cost silicon-based photodetector.

Full-duplex underwater wireless blue light communication.

Owing to its relatively low absorption loss and high data transmission rate, wireless blue light communication is becoming an increasingly attractive technology for underwater applications. Here, we demonstrate an underwater optical wireless communication (UOWC) system that communicates using blue light-emitting diodes (LEDs) with a dominant wavelength of 455 nm. Under the on-off keying modulation scheme, the waterproof UOWC system achieves a bidirectional communication rate of 4 Mbps based on the transmission control protocol (TCP) and exhibits real-time full-duplex video communication with a transmission distance of 12 m in a swimming pool, offering great potential for practical use in real-world scenarios, such as carried around or attached to an autonomous vehicle.

Full-duplex wireless deep ultraviolet light communication.

With recent advancements in deep ultraviolet (DUV) light-emitting diodes (LEDs) and solar-blind photodetectors, wireless DUV light communication is emerging as a novel technique, which can extend transmission ranges and avoid solar interference. Herein, a full-duplex, real-time wireless light communication system using 275 nm DUV LEDs is proposed. We adopted high-power DUV LEDs and designed a high-speed transmitter, a high-sensitivity receiver, and a main processing unit for the system. Furthermore, the DUV communication system, using a Reed-Solomon (RS) encoder and an on-off keying (OOK) modem with frequency control, achieves a 10 Mbit/s bidirectional data transmission rate within 5 m in free space, while a full-duplex video communication link is formed. The encapsulated DUV communication system described in this Letter provides a feasible scheme for confidential and anti-electromagnetic interference communication in Internet of Things (IoT) applications.

Photon-counting schemes for MIMO underwater wireless optical communication with arrayed PMTs.

Underwater wireless optical communication (UWOC) is a promising means of realizing large capacity and high rate in aquatic media. In this paper, a photomultiplier tube (PMT)-based multiple-input multiple-output (MIMO) UWOC system is investigated. Photon counting is an effective technique used to detect very low-level light. A PMT with an excellent photon-counting mode is adopted, and the performance in terms of the bit error rate is discussed. The received optical power can be predicted based on the detected photocount in each symbol period, and the received photocount distribution may be simulated through MATLAB. Furthermore, the optical link model and energy per bit with on-off keying are evaluated for different water types at a 10 m optical link distance. This MIMO-UWOC system combines the advantages of PMTs and the MIMO scheme and has the potential to realize long-distance optical link transmission.

Single-photon detection for MIMO underwater wireless optical communication enabled by arrayed LEDs and SiPMs.

Underwater wireless optical communication (UWOC) is a promising technology that can be a candidate to improve the communication capacity and speed in aquatic media. The aim of this study is to examine the performance of a silicon photomultiplier (SiPM) array-based multiple-input multiple-output (MIMO) UWOC system. A SiPM is a modern solid-state photodetector with extremely high sensitivity up to the single-photon level or a photon-counting ability, which helps in detecting extremely weak light signals after long-distance underwater channel attenuation. We clarify the basic characteristics and photon-counting detection mode of a SiPM. In particular, the photocount of a SiPM is approximated by a Gaussian distribution, and theoretical analysis shows that only 13.3 photons need to be detected during "1" symbol period to achieve a bit error rate of 10-3 in an ambient light environment. Moreover, a SiPM also has a better analog mode detection ability than an avalanche photodiode (APD) and realizes 2 Mbps analog communication owing to its unique array structure and high photon detection efficiency. Furthermore, MIMO, i.e., spatial diversity, is applied as an effective method to relax the link alignment, improve the system performance, and alleviate the effect of optical turbulence. In our experiment, with a photon-counting 6×3 MIMO scheme, an energy per bit of 7.38×10-9 J/bit is achieved at a scintillation index of 4.66×10-3 in a 10 m water tank with 1 Mbps on-off-keying (OOK) modulation. To the best of our knowledge, this is the first study on a MIMO-UWOC system based on the photon-counting mode of a SiPM array. This UWOC system combines the advantages of SiPMs and the MIMO scheme and has the potential to realize long-distance UWOC under optical turbulence.

Asymmetric optical links using monolithic III-nitride diodes.

Multiple-quantum well (MQW) III-nitride diodes can both emit and detect light. In particular, a III-nitride diode can absorb shorter-wavelength photons generated from another III-nitride diode that shares an identical MQW structure because of the spectral overlap between the emission and detection spectra of the III-nitride diode, which establishes a wireless visible light communication system using two identical III-nitride diodes. Moreover, a wireless light communication system using a modulating retro-reflector (MRR) enables asymmetric optical links, which forms a two-way optical link using a single transmitter and receiver. Here, in association with an MRR, we propose, fabricate, and characterize asymmetric optical links using monolithic III-nitride diodes, where one III-nitride diode functions as a transmitter to emit light, an MRR reflects light with the encoded information, another monolithically integrated III-nitride diode serves as a receiver to absorb the reflected light to convert optical signals into electrical ones, and the encoded information is finally decoded. Advanced monolithic III-nitride asymmetric optical links can be developed toward Internet of Things (IoT) deployment based on such multifunction devices.

Simultaneous transmission, detection, and energy harvesting.

Due to the electro-optic property of InGaN multiple quantum wells, a III-nitride diode can provide light transmission, photo detection, and energy harvesting under different bias conditions. Made of III-nitride diodes arrayed in a single chip, the combination allows the diodes to transmit, detect, and harvest visible light at the same time. Here, we monolithically integrate a III-nitride transmitter, receiver, and energy harvester using a compatible foundry process. By adopting a bottom SiO2/TiO2 distributed Bragg reflector, we present a III-nitride diode with a peak external quantum efficiency of 50.65% at a forward voltage of 2.6 V for light emission, a power conversion efficiency of 6.68% for energy harvesting, and a peak external quantum efficiency of 50.9% at a wavelength of 388 nm for photon detection. The energy harvester generates electricity from ambient light to directly turn the transmitter on. By integrating a circuit, the electrical signals generated by the receiver pulse the emitted light to relay information. The multifunctioning system can continuously operate without an external power supply. Our work opens up a promising approach to develop multicomponent systems with new interactive functions and multitasking devices, due to III-nitride diode arrays that can simultaneously transmit, detect, and harvest light.

Cost-effectiveness of nivolumab plus gemcitabine-cisplatin as first-line treatment for advanced urothelial carcinoma in China and the United States.

Objective: Nivolumab, recently proven in a phase 3 clinical trial (CheckMate 901) to enhance survival when combined with gemcitabine-cisplatin for advanced urothelial carcinoma. This study aimed to assess its cost-effectiveness against gemcitabine-cisplatin alone, from US and Chinese payers' perspectives. Methods: A partitioned survival model was established to assess the life-years, quality-adjusted life-years (QALYs), lifetime costs, and incremental cost-effectiveness ratios (ICERs) of nivolumab plus gemcitabine-cisplatin versus gemcitabine-cisplatin alone as first-line treatment for advanced urothelial carcinoma. Univariate, two-way, and probabilistic sensitivity analyses were conducted to assess the model's robustness. Additionally, subgroup analyses were performed. Results: Nivolumab plus gemcitabine-cisplatin and gemcitabine-cisplatin achieved survival benefits of 4.238 life-years and 2.979 life-years for patients with advanced urothelial carcinoma, respectively. Compared with gemcitabine-cisplatin, nivolumab plus gemcitabine-cisplatin resulted in ICERs of $116,856/QALY in the US and $51,997/QALY in China. The probabilities of achieving cost-effectiveness at the current willingness-to-pay thresholds were 77.5% in the US and 16.5% in China. Cost-effectiveness could be reached if the price of nivolumab were reduced to $920.87/100mg in China. Subgroup analyses indicated that the combination had the highest probability of cost-effectiveness in patients under 65 or with an Eastern Cooperative Oncology Group (ECOG) performance-status score of 0 in the US and China. Conclusion: Nivolumab plus gemcitabine-cisplatin first-line treatment for advanced urothelial carcinoma results in longer life expectancy than gemcitabine-cisplatin, but is not cost-effective in China at current price. However, cost-effectiveness is likely to be achieved in most patient subgroups in the US.

Integrated Sensing and Communication Chip Based on III-Nitride for Motion Detection.

Integrated Sensing and Communication (ISAC) involves incorporating wireless sensing capabilities into communication systems. The integration of ISAC affords improvements in the performance of the communication system, as well as the ability to perform high-precision motion detection, positioning, imaging, and other related functions. Therefore, it is highly valuable to develop an ISAC terminal device that has a high degree of integration and energy efficiency. Here, we propose an ISAC chip that utilizes the coexistence of luminescence and detection properties of III-nitride multiple quantum wells for motion detection and visible light communication. The ISAC chip includes both a transmitter and a receiver of visible light and is fabricated on a sapphire wafer with InGaN/GaN multiple quantum wells. A rotating mirror is used as the object for motion detection and modulates the light signal emitted by the transmitter in a reflected light path. The variation period of the photocurrent curve generated by the modulated light signal is consistent with the rotation period of the mirror. We also investigate the performance of this chip as a transmitter and transceiver terminal of visible light communication systems. The results of the study provide a promising approach for the integration of motion sensing and visible light communication.

AlInGaAs MQW Transceiver with Electro-optic Modulation Characteristics for Free-Space Optical Communication and Sensing.

Integrated transceivers with electro-optic modulation characteristics are valuable for free-space optical communications and sensing. We propose an AlInGaAs multiple quantum well (MQW) transceiver with electro-optic modulation characteristics over a broad spectral range. Two identical AlInGaAs MQW diodes on a single wafer are used to transmit and receive optical signals and provide obvious electro-optic modulation for broad-spectrum light. The photocurrent modulation ratio reaches 13.9 and 11.3 for white light and 1550 nm infrared light, respectively, with varying bias voltages. The transceiver can identify environmental changes and forward electrical signals with different frequencies in the form of superimposed optical signals.