Optical Power Transfer Research Articles

Wireless optical power transfer system incorporating a wide-field-of-view optical receiver.

This article introduces what we believe to be a novel receiver design featuring a compact, wide-field-of-view receiver and bidirectional gain medium that enables multiple receivers to charge simultaneously. The receiver was tested with a transmitter comprising a bidirectional broadband semiconductor optical amplifier and two wavelength division multiplexing filters. The receiver incorporates a ball-lens retroreflector equipped with anti-reflection and highly reflective coatings on its front and rear surfaces, respectively. The system has an overall efficiency of 1.23%, which can be improved further using suitable gain media. This receiver scheme has potential for seamless integration with various transmission systems that utilize the RBC technique and offers a wide field of view of approximately ±60 degrees.

A 6 Mbps 7 pJ/bit CMOS Integrated Wireless Simultaneous Lightwave Information and Power Transfer System for Biomedical Implants

A 6 Mbps 7 pJ/bit CMOS Integrated Wireless Simultaneous Lightwave Information and Power Transfer System for Biomedical Implants

Dynamic beam steering for wireless optical power transfer in IoT applications.

The alignment of a receiver with a pencil beam in a wireless optical power transfer (WOPT) system employing a resonance beam charging (RBC) technology limits the establishment of a resonance cavity. Accurate tracking necessitates precise and dependable monitoring, which requires the exact placement of transmitting and receiving devices. Herein, we present a concept of a two-dimensional (2D) beam steering mechanism for RBC-based WOPT systems utilizing dispersed laser beams. The proposed approach allows a significant improvement, including reduction of scanning times and minimization of errors, in relation to conventional pencil-beam-based systems. Experimental results reveal 14% faster acquisition time efficiency, an 18% improvement in pointing accuracy, and a 24% enhancement in tracking accuracy. These results establish the prerequisites for the implementation of dispersed beam steering in the RBC-based WOPT system. This capability empowers the system to charge movable devices and Internet of Things devices consistently in smart factories.

Energy harvesting techniques for sustainable underwater wireless communication networks: A review

The emergence of various underwater wireless communication systems has been on the rise due to increasing human activities in the marine environment. In underwater wireless communication networks (UWCNs), several communication devices, such as sensors and autonomous underwater vehicles (AUV) are interconnected to expand communication coverage, monitoring, information gathering, and surveillance. These devices operate on batteries, making their replacement and recharging difficult. Consequently, sustaining the operational lifetime of UWCNs is deemed a major challenge. This leads to the development of various energy harvesting (EH) techniques to perpetuate the power supply to underwater devices. In this paper, we present a review of various energy sources and EH techniques applicable to UWCNs. To achieve this, we classify the energy sources into various categories in order to establish the peculiarities of each source and the type of harvester applicable to each category. Based on this classification, we present discussions on various contributions of articles related to applications of EH techniques in UWCNs. In addition to various insights gained from the presented papers, we establish that energy harvesters based on triboelectric effect, piezoelectric effect, sediment microbial fuel cell, acoustic, and optical power transfer are suitable for low-power (milliwatt-order) consuming devices such as sensors. Also, for devices with high power consumption requirement, such as AUV, solar and inductive power transfer-based harvesters should be employed. Furthermore, we identify several technical challenges that should be taken into consideration during the planning and system design phases. Finally, we highlight open research areas that could further improve the EH and communication processes in UWCNs.

Optical engineering of infrared PbS CQD photovoltaic cells for wireless optical power transfer systems

Infrared photovoltaic cells (IRPCs) have attracted considerable attention for potential applications in wireless optical power transfer (WOPT) systems. As an efficient fiber-integrated WOPT system typically uses a 1550 nm laser beam, it is essential to tune the peak conversion efficiency of IRPCs to this wavelength. However, IRPCs based on lead sulfide (PbS) colloidal quantum dots (CQDs) with an excitonic peak of 1550 nm exhibit low short circuit current (Jsc) due to insufficient absorption under monochromatic light illumination. Here, we propose comprehensive optical engineering to optimize the device structure of IRPCs based on PbS CQDs, for 1550 nm WOPT systems. The absorption by the device is enhanced by improving the transmittance of tin-doped indium oxide (ITO) in the infrared region and by utilizing the optical resonance effect in the device. Therefore, the optimized device exhibited a high short circuit current density of 37.65 mA/cm2 under 1 sun (AM 1.5G) solar illumination and 11.91 mA/cm2 under 1550 nm illumination 17.3 mW/cm2. Furthermore, the champion device achieved a record high power conversion efficiency (PCE) of 7.17% under 1 sun illumination and 10.29% under 1550 nm illumination. The PbS CQDs IRPCs under 1550 nm illumination can even light up a liquid crystal display (LCD), demonstrating application prospects in the future.Graphical

A comprehensive review of optical wireless power transfer technology

A comprehensive review of optical wireless power transfer technology

Optical Wireless Power Transfer for Implanted and Wearable Devices

Optical wireless power transfer (OWPT) has been employed in the literature as a wireless powering approach for implanted and wearable devices. However, most of the existing studies on this topic have not studied the performances of OWPT systems when light is transmitted through clothing. This research therefore contributes to investigate the effects of clothing on OWPT performances from both theoretical and experimental perspectives. An obtained experimental result indicates that a single light-emitting diode (LED) transmitter is able to perform the OWPT through white cotton clothing, but failed with another dark cotton clothing, even at a small transmitting distance. Hence, this research proposes to employ LED arrays as optical transmitters to improve the OWPT system capability in terms of the wirelessly transmitted power, transmitting distance and system tolerance to misalignments, whilst keeping the system safety, low cost and simplicity. Consequently, a theoretical formula for the power transmission efficiency made by an LED array through clothing is proposed and then is verified with experimental results. Furthermore, the important role of multiple light reflections at the surfaces of clothing and the LED array transmitter is pointed out.

AlGaN as an electron transport layer for wide-bandgap perovskite solar cells

Perovskite solar cells are expected to be applied as photoreceivers for high-efficiency optical wireless power transfer for electric vehicles. The use of aluminum gallium nitride (AlGaN) as an electron transport layer (ETL) for wide-gap perovskite solar cells is hereby proposed in this paper. The electrical properties and energy-band alignment of AlGaN deposited by either hydride vapor phase epitaxy or metal-organic CVD are investigated. AlGaN shows a higher conduction band level than conventional ETL materials. Simulation of the performance of a perovskite solar cell with CH3NH3PbBr3 as the absorbing layer and AlGaN as the ETL was performed using a solar-cell capacitance simulator. The results suggest that AlGaN increases the power conversion efficiency of the solar cell by improving the conduction band offset between the perovskite layer and the ETL.

Pulse distortion caused by waveguide inhomogeneity in nonlinear optical wavelength converters

Low-noise integrated all-optical wavelength converters that can be operated in short pulse regime are essential tools to overcome contention resolution in a modern communication network, based on wavelength division multiplexing. Any imperfect functionality in such devices causes non-ideal optical power transfer to the converted data pulses. All imperfections during the preparation and operation of the wavelength converters can be addressed to the waveguide inhomogeneity which distorts data pulses to be converted. This paper reports different waveguide inhomogeneity effects on the pulse distortion while using periodically poled lithium niobate waveguide as wavelength converters. Three types of chi ^{(2)}-based nonlinear optical processes, including second harmonic generation, difference frequency generation, and cascaded second harmonic generation/difference frequency generation are numerically studied to show that any constant, linear, and quadratic waveguide inhomogeneity causes short pulse (down to 1 ns) distortion in such wavelength converters. In addition, it is shown that the reconstruction of textrm{sech}^2-shaped generated pulses is possible, when suitable upside-down quadratic variations of obtained inhomogeneity are deliberately induced in the waveguide. Notably, for pulsed second harmonic generation, the generated pulse can be compressed using an upside-down quadratic phase mismatch.

Long-Range Optical Wireless Information and Power Transfer

Simultaneous wireless information and power transfer (SWIPT) is a remarkable technology to support both the data and the energy transfer in the era of Internet of Things (IoT). In this article, we proposed a long-range optical wireless information and power transfer system utilizing retro-reflectors, a gain medium, a telescope internal modulator to form the resonant beam, achieving high-power and high-rate SWIPT. We adopt the transfer matrix, which can depict the beam modulated, resonator stability, transmission loss, and beam distribution. Then, we provide a model for energy harvesting and data receiving, which can evaluate the SWIPT performance. Numerical results illustrate that the proposed system can simultaneously supply 0–9 W electrical power and 18-bit/s/Hz spectral efficiency over 20-m distance.

Laser-Based Dynamic Optical Wireless Power Transfer for Electrified Vehicles Covered with Solar Cells

This research proposes and theoretically analyzes a dynamic optical wireless power transfer (OWPT) system for wireless charging of aerial and ground electric vehicles (EVs). In the proposed system, an overhead facility is utilized to host laser transmitters, while solar arrays are attached on EVs to be energy receivers. Moreover, laser transmitters are able to rotate, point upward and downward to wirelessly charge aerial and ground EVs. Owing to the movement of EVs, the wirelessly transmitted power and energy to EVs are varying with time and distance, hence are not as simple as in the case of static wireless charging, i.e. when EVs are stopped or hovering. This paper therefore proposes an analytical analysis for the dependence of wirelessly transmitted laser power and energy to moving EVs on the transmitting distance, utilizing the exponential integral function. The derived results reveal that there exist a unique maximum power point and a unique maximum energy point, due to the monotonic increase and decrease of the transmitted power and energy. These give rise to determining the optimal distances at which the wirelessly transmitted laser power and energy are maximum. Numerical simulations are then carried out to validate and illustrate theoretical results.

Dynamic Optical Wireless Power Transfer for Electric Vehicles

This research proposes and analyzes a dynamic optical wireless power transfer (OWPT) system for wireless charging of aerial and ground electric vehicles (EVs). In this system, an overhead facility is proposed to locate laser transmitters, renewable energy resources, and energy storage devices. There are laser transmitters on the facility’s roof pointing upward to wirelessly charge aerial EVs, while the other laser transmitters on the facility’s ceiling pointing downward to wirelessly charge ground EVs. All laser transmitters are able to rotate around the normal direction to track and continuously charge aerial and ground EVs while they are moving, due to the equipped tracking cameras. Analytical mathematical formulas are then derived for the wirelessly transmitted power and energy. Based on those formulas, the unique existence of maximum power and energy points are proved. Furthermore, those maximum points are shown to be inversely linearly dependent on the environment attenuation coefficient, i.e. on weather conditions. Numerical simulations are carried out to validate and illustrate the obtained theoretical results. Finally, implications of those results on the design of ground EVs are introduced, based on which a comparison with another wireless power transfer technology reveals that the proposed dynamic OWPT system is more effective.

100 Gb/s NRZ OOK signal regeneration using four-wave mixing in a silicon waveguide with reverse-biased p-i-n junction.

A silicon waveguide with reverse-biased p-i-n junction is used to experimentally demonstrate all-optical regeneration of non-return-to-zero (NRZ) on-off keying (OOK) signal based on four-wave mixing. The silicon waveguide allows a high conversion efficiency of -12 dB. The 0.22 dB (1.1 dB) quality (Q) factor and 0.74 dB (6.3 dB) extinction ratio (ER) improvements on average are achieved for 100 Gb/s (50 Gb/s) NRZ OOK signal regeneration at different receiving powers via the optimal match between the input signal optical power and input-output transfer curve. To the best of our knowledge, this silicon-based all-optical regenerator exhibits superior regeneration performance, including large ER and Q factor improvements, and the highest regeneration speed of NRZ OOK signal, and it has wide applications in 5 G/6 G networks.

Coaxial Mach-Zehnder Digital Strain Sensor Made from a Tapered Depressed Cladding Fiber.

An in-line digital optical sensor was proposed. It was built from a tapered depressed-cladding single-mode fiber and modeled as a coaxial Mach–Zehnder interferometer. The principle of operation of the optical digital sensor is based on the computation of the number of optical power transfer turning points (PTTP) from the transmission data of the component. Biconic tapers with high values of PTTP, high spectral resolution, high extinction ratio, and low insertion loss were modeled, fabricated, and characterized. As a proof of concept, an in-line digital strain sensor was fabricated and characterized. It presents a free spectral range of 1.3 nm, and produced 96 PTTP, at λ0 = 1.55 μm, under stretch of ΔL = 707 µm, therefore producing a digital resolution of 7.4 µm/PTTP. The sensor also produced a quasi-symmetric response to stretch and compression.

Power Hotspots in Space: Powering CubeSats via Inter-Satellite Optical Wireless Power Transfer

The desire to provide global Internet coverage is driving traditional terrestrial networks to evolve towards an integrated space and terrestrial network wherein miniaturized satellites, a.k.a CubeSats, remain at the core. Although both academia and industry are investigating the potential of CubeSats to provide global connectivity, they still fall short of the power generation capacity to enable high data rate communication in gigabits per second range. This article spotlights on alternate sources of energy that can provide the power demands needed for high data rate communication. We present the concept of power HotSpots wherein the bigger satellites in low earth orbits (LEO), having power generation capacity much larger than CubeSats, can transfer their excess energy to CubeSats in need, using optical wireless technology. This provides a business opportunity for larger enterprises having the capability of launching bigger satellites to sell their power to CubeSats. As a proof of concept, this article presents a basic simulation regarding optical wireless power transfer (OWPT) to CubeSats. In addition, we highlight future research challenges in this area to maximize OWPT.

Long-range wireless optical power transfer system using an EDFA

A wireless optical power transfer (WOPT) system using an erbium-doped fiber amplifier as an optical power source is proposed to achieve long range, high power, and hazard-free power delivery in the air. The transmitter generates a wide band of amplified spontaneous emission around the central wavelength of 1550 nm. A wavelength division multiplexing (WDM) filter (λ=1552.25 nm) is deployed to obtain a safe narrowband beam illuminating the receiver units. A ball lens retroreflector reflects a small portion of the incident beam back to the transmitter, establishing a closed ring resonance loop. An improved safety mechanism is proposed to terminate the resonance when an obstacle blocks the transmitter-receiver line of sight. The measured incident power of 1 W decreases to 0.79 mW after the WDM filter is deployed which is well within defined maximum permissible exposure standards. For the demonstration of free-space transmission, transmitter-receiver separation is extended to 30 m. The experimental results show that a single-channel WOPT system provides an optical power of 400 mW with a channel linewidth of 1.027 nm over 30 m and an electrical power of 85 mW is acquired using a gallium antimonide photovoltaic.

Performance Analysis of a Perovskite-Based Thing-to-Thing Optical Wireless Power Transfer System

This paper presents an analysis on the performance of an optical wireless power transfer system in which optical transceivers made from a perovskite are used. Experiments are performed under different settings, whose resulted data reveal interesting findings. First, system performance is only matched with the existing theory when no collimating lens is employed. Hence, a data-driven mathematical model is proposed and verified when a collimating lens is used. Second, a collimating lens helps increase the amount of wirelessly transferred power and the transfer distance if perfect alignment between optical transceivers is guaranteed, but substantially limits the sliding distance between them otherwise.

Toward Thing-to-Thing Optical Wireless Power Transfer: Metal Halide Perovskite Transceiver as an Enabler

This paper proposes a novel conceptual system of optical wireless power transfer (OWPT) between objects, which is different from the existing OWPT systems such that a single device—an optical transceiver—is employed. This optical transceiver, which is capable of both absorbing and emitting light, is fabricated from a metal halide perovskite known for its superior features that can help significantly reduce the whole system size and cost. The proposed system contributes to realizing a thing-to-thing OWPT network, in which surfaces of objects/things are covered by perovskite transceivers (fully or partially), enabling them to wirelessly charge or discharge from the others.

Understanding the Future Communication: 5G to 6G

This article enrolls the development and review of the 6G(6th Generation) wireless communication technology which is expected in the 2030s and is the first of its kind to review 6G concepts in IoT (Internet of Things). Wireless communication technology will make communication between entities and these technologies are separated as different generations. 6G wireless communication technology will be an application of IoT by bringing the world closer. 6G network implementation will be a promising and developing field in wireless communication technology. In this paper, we discuss how the 6th Generation of wireless communication technologies overcomes the existing problems faced by the previous generation (5G). We have a general architecture for wireless communication technology. By adding some new key concepts (Artificial Intelligence, optical wireless communication, terahertz frequency, and wireless power transfer) to this architecture we can produce a new generation (6G) of wireless technology. This paper also describes the advantages and challenges which can be faced by the 6th generation of wireless communication. A few of the key points trends behind the growth of the 6G wireless communications are green communication, network traffic, intelligent network, localization, new spectrums, high reliability, low latency, high data bit rate, network availability. The 6G will provide a better communication system in the future by ensuring future trends.

Wearable and Battery-Free Health-Monitoring Devices With Optical Power Transfer

Wireless epidermal wearable devices attract interests and expectations as a tool for personalized, low-cost health monitoring technology. The concept of the wireless attachable personal health monitoring devices has been more widely considered by combining them with biosensors. To bring the most advantage out of the structure of the epidermal attachable device, a battery-free approach was introduced to reduce the volume and extend the lifetime of the device. In this work, an energy harvesting technology and noninvasive sensor were applied with the attachable battery-free devices as a wireless power system and painless measuring system. A glucose sensor was used as an example to develop the wireless wearable device for diabetes-monitoring. The device consists of two functional parts: an optical power transfer and an electrochemical sensing part. The operation starts when the optical power transfer part accumulates power from series-connected photovoltaic cells and intermittently supplies the power to the electrochemical sensing part. In the electrochemical sensing part, an amperometric method was used for controlling the oxidation voltage and measuring a faraday current from the noninvasive sensor and current as brightness and duration of light pulses from a light-emitting diode (LED). The experiment results show that the device works as expected for a variety of glucose concentrations.