Transceiver assembly for free space power transfer and data communication system

Abstract

To provide a transceiver assembly for free space power transfer and data communication using laser light in a wireless power transfer system.SOLUTION: In a transceiver assembly, a photodiode assembly 62 of a receiver 60 receives a high-power laser beam from a transmitter and converts the high-power laser beam into an electrical energy. A voltage converter 64 adjusts an input impedance based on a voltage measurement of the photodiode assembly 62 to maximize a power transfer from the photodiode assembly 62 to an energy storage device 65 electrically coupled to the voltage converter 64. An IR LED 78 and an IR communication photodiode 76 are in free space optical communication with the transmitter. The IR LED 78 sends a signal indicating the presence and a location of the transceiver to the transmitter at least when the energy storage device 65 requires charging.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a transceiver assembly for free-space power transfer and data communications, particularly using laser light. [Background technology]

[0002] Wireless power transfer offers an attractive solution for increasing the mobility and convenience of electronic and electrical devices, enhancing device design flexibility in consumer electronics, industrial equipment, the Internet of Things (IoT), and healthcare applications. For consumer electronics products such as smartphones, watches, and other portable devices, near-field (NFC) wireless power transfer is an intermediate solution, but it falls short of more flexible and useful long-term solutions. For near-field wireless power transfer, the powered wireless device typically includes a receiver, consisting of a metal coil connected to an impedance matching network and a rectifier, as used to power loads such as batteries. The powering device typically includes a transmitter, consisting of a coil similar to the receiver, connected to an oscillator and a power source. When the transmitting device is supplied with a time-dependent voltage and corresponding current, the coil current generates a time-dependent magnetic field that periodically alternates between high and low states, which couples with the receiver coil and transfers power from the transmitting device to the wireless device. Capacitive coupling between metal electrodes based on high-frequency electric fields can also be utilized for near-field power transfer. In either case, the wireless device must be physically close to the transmitting device and often must be precisely aligned, which is a factor limiting the usefulness of the technology. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 6,633,026 [Patent Document 2] U.S. Patent No. 7,068,991 [Patent Document 3] U.S. Patent No. 7,423,767 [Patent Document 4] US Patent Publication No. 2010 / 0012819 [Patent Document 5] U.S. Patent No. 5,229,593 Summary of the Invention [Problem to be solved by the invention]

[0004] Long-distance wireless power transfer typically relies on power transmitted by beams of electromagnetic radiation, such as radio frequencies, laser beams, etc. Limiting factors associated with long-distance power transfer include directionality, safety, and overall power transfer efficiency. The use of laser beams to transfer power, commonly referred to as "power beams," requires a direct line of sight between the transmitter or light source and the receiver or load, which raises safety concerns as laser radiation can cause blindness in humans and animals exposed to low power levels for short intervals, while high power levels over sustained periods of exposure can be lethal.

[0005] Several potential solutions to some of the limitations of power beams have been developed. For example, in U.S. Patent No. 5,623,499, one or more light sources are generated around a single power beam, forming a virtual insulator. If any of the surrounding light sources are obstructed, a trigger is generated to turn off the power beam. This system, in this patent, relies on a receiver that is physically separated from the wireless device and is primarily stationary as a system. It lacks the ability to track mobile electronic and electromechanical devices. The system also relies on a two-part process to turn on the power beam: first, searching for a light source at a known location and power beam for a receiver needing power; and, once found, turning on the virtual insulator. U.S. Patent No. 5,623,499 describes a complex power transmission system that includes microwave or laser beams and provides both power transfer and data communication, but does not describe the technical details of how power is transmitted. Like U.S. Patent No. 5,623,499, the system described in U.S. Patent No. 5,623,499 relies on the transmitter sending a priority power request signal to the receiver, which wastes power when there are no devices or only fully charged devices within range of the transmitter.

[0006] Another approach described in Patent Document 3 relies on mechanical beam steering to align the receiver with the received power signal, but this introduces many drawbacks related to the mechanical aspects of the system. The device location and tracking is not described in sufficient detail to allow a skilled artisan to implement the invention in a physical system. This patent only describes detecting the receiver based on reflections from the receiver. This, in turn, requires locating the center point of a reflective ring and comparing the reflected light from each of a number of mapped points. As the transmitter beam approaches the center of the ring reflector, it impacts the photovoltaic device, causing a significant decrease in reflection. The same effect occurs as the transmitted beam moves radially away from the center of the ring, thereby missing the target. Reflection also decreases significantly. There is no explanation of how these two states are distinguished. Similarly, Patent Document 4 discloses a transmissive laser and lens attached to a pointing mechanism. The described beam steering solution requires a camera to locate the photoelectric transducer, e.g., a photodiode, such as a receiver, with sufficient precision to point a beam with a spot size of less than 10 mm. In practice, this places significant size constraints on the optical elements of wireless devices, and all safety functions are imposed on the transmitter, which is not tolerant to transmitter failure, whereas in the invention described herein, safety is handled by both the transmitter and receiver. Patent document 5 describes fixed transmitters and receivers that operate at safe levels when the power beam is not received by the receiver, and when received, it is not at a dangerous level. The mobility limitations of the transmitter and receiver are appropriate for permanent structures or terminal devices, such as broadcast towers or communication stations, rather than household appliances or mobile electromechanical systems.

[0007] A key element of a far-field power transmission system is the receiver, and a key aspect of the receiver is how light energy is converted into electrical energy. One existing solution to optimizing electrical conversion is to increase the size of the photosensitive area of ​​the photonic sensor. However, this requires more physical space at the receiver, which reduces utility and increases device cost. Solar cells, such as solar arrays, can be much more efficient at converting photons into electrons, but are generally optimized for visible light and require a significant amount of physical space. For example, the average size of solar panels used in rooftop installations is 65 inches by 39 inches, with individual solar cells being 6 inches by 6 inches. Such spheres have a hollow volume with small inlet and outlet ports, which reflect incoming light from their internal surfaces and send it to an optoelectronic device that converts the light into energy. Such spheres tend to be inefficient and require more physical space. They are generally too large to be useful in mobile devices and many other applications. Due to significant heat generation, they require less physical space and can operate over a wide bandwidth, but are inefficient because they convert light energy into heat and then into electrical energy. Many sensors operating in photovoltaic mode implement contact arrangements that obscure (through electrical connections) the incident light onto the photosensitive area, thereby reducing coupling efficiency. Similar devices can be constructed and emitted from lasers without the material configurations and geometries specifically designed for single-mode light. [Means for solving the problem]

[0008] A transceiver assembly for a wireless power transfer system is disclosed. The transceiver assembly includes a transceiver system including a photodiode assembly configured to receive a high-power laser beam from a transmitter and convert the high-power laser beam into electrical energy, and a voltage converter configured to adjust an input impedance based on a voltage measurement of the photodiode assembly to maximize power transfer from the photodiode assembly to an energy storage device electrically coupled to the voltage converter. Adjusting the input impedance increases charging efficiency of the energy storage device. The transceiver system includes a light-emitting diode and a photodiode configured to enable free-space optical communication with the transmitter. The light-emitting diode transmits a signal to the transmitter indicating the presence and location of the transceiver at least when the energy storage device requires charging. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a block diagram showing a transmitter according to an embodiment. [Figure 2] FIG. 2 is a diagram of a transmitter housing according to an embodiment. [Figure 3] FIG. 1 is a block diagram illustrating a receiver according to an embodiment. [Figure 4A] FIG. 10 is a diagram of a compound parabolic collector mirror of a receiver according to an embodiment. [Figure 4B] FIG. 10 is a diagram of a compound parabolic collector mirror with a tapered receiver entrance according to another embodiment. [Figure 5] FIG. 2 is a cross-sectional view of a photodiode assembly of a receiver according to an embodiment. [Figure 6] The penetration depth of light is shown as a function of its wavelength. [Figure 7] 7 is a cross-sectional view further illustrating a portion of the photodiode assembly of FIG. 6 to better illustrate the light absorption and electron conversion functions of the photodiode assembly, according to an embodiment. [Figure 8]6 is a cross-sectional view further illustrating the PIN structure and carrier transport mechanism of the photodiode assembly of FIG. 5, according to an embodiment. [Figure 9A] 6 illustrates a top view of the back contact pattern of the photodiode assembly of FIG. 5, according to an embodiment. [Figure 9B] 6 illustrates a top view of the back contact pattern of the photodiode assembly of FIG. 5 according to another embodiment. [Figure 10] 10 shows a cross-sectional view of the photodiode assembly of FIG. 5 with the back contact pattern shown in FIG. 9 integrated into a printed circuit board (PCB) configuration, according to an embodiment. [Figure 11] FIG. 11 is a top view of the PCB configuration of FIG. [Figure 12] 1 is a cross-sectional view for optical interaction between a Fresnel lens and a photodiode array, according to an embodiment. FIG. [Figure 13] FIG. 2 is a diagram of a lens stack according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The wireless power transfer system of the present disclosure may consist of two core elements: a transmitter and a receiver. The transmitter and receiver simultaneously enable efficient transmission of power wirelessly from the transmitter to a single receiver or multiple receivers, using a collimated infrared laser beam. The transmitter is stationary, connected to a reliable power source, moderately cost-sensitive, and moderately space-constrained. The receiver may be mobile, may include a battery or capacitive power source (i.e., from which it draws and consumes power, i.e., output and input), and is cost-sensitive and space-constrained.

[0011] From an operational perspective, the transmitter may be responsible for sensing the environment, detecting the presence of suitable receivers, and participating in two-way communication with those receivers to determine the precise location of those optics. During this initial device location, a safety system is implemented and maintained in constant operation during nominal function, as further described below. The transmitter also controls the transmission of an infrared (IR) laser power beam and the associated optics for powering the receiver optics in a manner that meets regulatory safety requirements. To maintain system safety, the transmitter may strive to shut off the high-power laser beam as quickly as possible when the safety system detects an interruption, preventing expected information from being received, causing the power beam to shift, or the receiver's location to be lost. The transmitter receives, processes, stores, and forwards data about connected receivers to a centralized digital database.

[0012] The receiver has the ability to broadcast its presence to the environment and communicate bidirectionally with the transmitter. The transmitter has the ability to adjust wireless power transfer priorities based on the exchange of credentials with each of multiple potential receivers, and can rank the priority of each receiver to establish an order in which each receiver is charged. Priority preferences can be set by the user / owner of the wireless power transfer system, or can be pre-scheduled in the same manner and left determined by factory settings. The receiver can also cooperate with the transmitter to determine the precise location of the receiver's optical elements. Once the receiver communicates with or establishes communication with the transmitter, it can continuously transfer power and charging status information to the transmitter.

[0013] Given the specific power and timing constraints associated with the safe wireless transmission of power, the receiver transmits device-specific information back to the transmitter (i.e., sensor data is passed to the transmitter via a free-space optical communication (FSOC) link, given the appropriate overhead for wireless power transmission). Similarly, the transmitter communicates commands or data via the FSOC link to a designated receiver with the appropriate overhead for wireless power transmission. The transmitter transmits system- or device-specific information or diagnostics to a cloud or connected database via a wireless or wired connection. Thus, the transmitter and receiver establish a bidirectional data communication channel, allowing the transfer of data unrelated to the device's own power operation or location. Various IoT or other similar devices or devices can receive both power and other data and / or commands through a wireless power transmission system. For example, a smart thermostat transmits room temperature information to a wireless power transmission system, which then forwards that temperature information to an HVAC controller or automatic window shades that are powered via the wireless power transmission system.

[0014] A diagram of an embodiment of a transmitter is shown in FIG. 2. As shown, transmitter 10 includes a power supply 12, a laser system 14 generating one or more power beams and one or more optical beams, an optomechanical device (optomechanics) 16 for beam steering, a processor 18, and associated power control logic 19 for controlling laser system 14 and optomechanical device 16, as well as communications and safety subsystems. Transmitter 10 is capable of performing all of the key computational processes necessary to keep the system accurate and safe. At the logic level, processor 18, such as an ARM Cortex processor, provides high-level control over most transmitter functions. The processor includes command sets specific to various transmitter functions, such as beam steering, power beam output control, FSOC data processing, thermal control, sensor data transfer, sensor fusion, and system reporting. An additional housekeeping integrated circuit (IC) 11 may be utilized to provide overcurrent and overcurrent protection / monitoring for DC / DC converter / regulator 15, as well as overall fault management, reporting, and elimination. This is particularly useful when wireless power transfer systems are used in medical, aerospace, and other higher risk environments where there is a great need to maintain the system's safety from various failures that may occur, thereby creating fault-tolerant systems that are commonly required by government regulations for devices used in these applications.

[0015] In this embodiment, power for the transmitter 10 is derived from a regulated power supply 12 coupled to a laser AC / DC power supply 20 via a power line filter and ESD protection circuit 13. The power supply 12 can take many forms, such as a high-voltage battery, a wall outlet, or other secondary generator off the main power grid. The input signal can be 120Vac to 240Vac AC, plugged into a standard wall outlet (15A / 20A in North America, 16A+ in the EU), or a standard DC voltage with amplitude commensurate with system requirements. The input power 12 can pass through the power supply 20, which may include a two-stage converter to convert the AC voltage to a DC voltage, and a DC-DC converter / regulator 15 to adjust the output to multiple voltages. From there, the voltage is downconverted as needed and supplied to the various subcircuits.

[0016] In this embodiment, three power buses may be included, such as a laser bus for biasing the laser component, a logic bus for biasing the processing and computational components, and a motor bus for biasing the electromechanical loads or subsystems. Each subsystem of the transmitter 10 may draw power from one of these three buses. To isolate noise, the power buses may be isolated from each other via passive components, partitioning, or on-board shielding (e.g., an egg crate). The logic bus may be provided via a complex programmable logic device (CPLD) 22. As one skilled in the art will appreciate, different buses and / or power distribution methods may be used depending on the components and converters used.

[0017] The power supply 20 for the laser diode of the laser system 14 may be a highly regulated (stabilized) current supply operating in current control mode. The supplied current is monitored against a current setpoint to generate an error value. The error value may be fed back to the power supply logic and / or controller / laser diode driver 17 to fine-tune the output. The power supply 20 and / or the laser diode driver 17 coupled to the power supply 20 may also incorporate a command input associated with the output from the CPLD 22 of a safety system that serves to disable the power supply 20 and / or the laser diode driver 17 should any partial or complete occlusion of the fault light beam path be detected or for other safety reasons. To quickly shut off the power supply or driver, the bandwidth of the power supply may be greater than 5 kHz. The laser source 24 may be, but is not limited to, a laser diode on a C-mount / TO-can / integrated module package and may be fixed in place. To allow a transmitter to accommodate multiple receivers, a number (n) of identical laser diode sources 24 may be supplied from the same power supply 20 or by separate power supplies for each laser diode. A heat sink with or without an active cooling device may be included to temperature regulate the power supply, regulator, and driver components.

[0018] In embodiments, the output of laser source 24 may be split (branched) into two or more separate beam paths by beam splitters, optical filters, or mirrors. The resulting beams can be used in separate power beam channels to feed two or more devices from a single source. In embodiments where a single source can feed multiple receivers, a series of active optical devices can be used to reduce the optical output power for a single channel when one receiver is blocked but not the others, thereby eliminating the need to turn off a single laser source to both devices when a blockage occurs in one device.

[0019] In addition to the power beam being supplied from the laser bus, a different, lower power beam may be supplied by one or more FSOC lasers. FSOC channels can be established using single or multiple light-emitting diodes (LEDs) or low-power laser diodes for transmitting optical data and single or multiple photodiodes for receiving optical data. FSOC components can be configured to operate from either a laser or a logic bus, depending on the voltage requirements and efficiency of the subsystem. Transmitters and receivers can be modularized by implementing the same FSOC components, where a transmitting device from the transmitter communicates with a receiving device on the receiver, as well as a transmitting device on the transmitter.

[0020] The logic bus can provide reference voltages to all components controlling the logic functions, which may include a CPLD (safety) 22 (such as a CPLD from XILINX or Intel), a processor 18 (such as an Intel, Freescale, etc.), a microcontroller unit (MCU) 26 (such as an ARM Cortex or similar products from XILINX or NVIDIA), a camera 28, auxiliary sensors or secondary power regenerators, and finally active optical applications required for future device functionality (such as variable beam splitters / attenuators, polarizers, etc.).

[0021] The motor bus serves to supply the appropriate voltage to a two-axis beam steering brushless DC (BLDC) motor 30 as the primary optomechanical component 16. The two-axis motor 30 includes reflective or refractive optics and is used to project light to provide a wide cone of light extending from the optical interface of the transmitter housing 32 (as further shown in FIG. 2 ) to the wall and / or floor locations of a staged room. Control of the intensifying motor 30 via a feedback loop is provided by a motor controller 31, which is a logic-driven component of the MCU processor 26. Alternative methods of beam steering, such as MEMS mirrors, gimbal assemblies, Risley prisms, liquid crystal waveguides, optical phased arrays, or other solid-state beam steering assemblies, may be used as are well known to those skilled in the art and are not excluded from this disclosure.

[0022] As noted above, processor 18 provides most of the logic control for the transmitter and partial FSOC photodiode 27 and camera 28 monitoring, FSOC LED 25 commands, and beam steering logic commands for optomechanical system 16. Communication coupling between FSOC LED 25 and FSOC photodiode 27 may be provided by an IR transceiver 29, which is coupled to processor 18 and includes an encoder / decoder. A separate MCU processor 26 may provide auxiliary inputs to optomechanical system 16 to better assist with beam steering accuracy and thermal requirements, including, but not limited to, commanding a fan or thermal energy generator (TEG) 33 or cooler based on thermal measurements from a thermocouple or temperature sensor (not shown), adjusting beam steering based on fine accelerometer 34 feedback, and changing position or configuration based on the requirements of potential future active optics (not shown). Power management for TEG 33 may be provided by a step-up transformer 35.

[0023] Closed-loop control of the FSOC LED 25, which directly assists in receiver distance detection, is provided via a computer vision-based algorithm that determines the required intensity of the FSOC LED transmit signal based on pre-calibrated lighting conditions in the room or location, as detected by the camera 28 and processed by the processor 18. In other words, if a significant ambient temperature or natural light shift occurs in the room or location, it may be desirable for the disclosed wireless power transfer system to utilize the image captured by the camera 28 to adjust, i.e., increase, the output power of the FSOC LED 25. If the lighting in the room or location falls below the pre-calibrated lighting conditions, the output power of the FSOC LED 25 may be reduced. By adjusting the amount of required output power, transmission efficiency can be achieved based on the feedback lighting conditions of the operating environment.

[0024] The CPLD 22 may be a separate IC, its functions may be integrated into a more complex IC, or it may be a dedicated safety / control component and may be responsible for the overall command and control of the safety subsystem. This includes shut down commands to the laser diode power supply 20, processing optical power levels from a monitor photodiode or optoelectronic sensor (not shown), generating error or fault messages to the processor 18, and other actions related to maintaining user safety as a result of impingement of a high power laser beam. The CPLD 22 may require the presence of two signals: to enable the laser source 24 to reach optimal power beaming levels; 1) an additional processor 26; and 2) Main Processor 18. Additional electrical elements (most not shown) include passive devices responsible for filtering, grounding, shielding etc., devices for power conversion, transmission of telemetry via WiFi, Bluetooth or a dedicated RF link, sensors required for initial calibration, and additional indicator LEDs or screens (not required for system functionality etc.) provided for the user's benefit.

[0025] The optical and opto-mechanical components of the transmitter 10 can shape and control the laser beam characteristics in two axes. The first set of collimating optics 40 is located away from the end face of the laser diode 24. The collimating optics 40 may be a shaped set of n lenses. Its function is to generate a beam parallel to two axes for injection into the beam steering assembly. The collimating optics 40 may include a fast-axis collimator (FAC) and a slow-axis lens to shape the beam in two dimensions. The FAC can consist of an aspheric cylinder of appropriate diameter and thickness, a ball lens, a small section of fiber optic cable, or multiple optics used in combination or independently. A small truncated section of suitable fiber optic cable can be used as an inexpensive and quick lens for fast-axis collimation. In an embodiment, a cross section of fiber optic cable slightly longer than the longest dimension of the laser end face is mechanically fixed to the front face of this face with its long axis parallel and adjacent to the long axis of the face. Fiber optic cables function similarly to aspheric cylindrical lenses by collimating all diverging light rays from a laser or small light source. This method provides a faster way to achieve collimation than using delicate and often expensive fast axis lenses.

[0026] The laser diode 24 may be uniquely designed to generate light with a single polarization by custom shaping or growing the laser cavity region. Because reflections at the receiver surface are problematic in high-power free-space optical systems, ensuring the generated light is p-polarized can reduce reflections even when the beam's angle of incidence exceeds 60 degrees. This can be achieved by adding a p-polarizing wave plate 42 placed above the corresponding collimating optics 40 (i.e., there may be n wave plates 42, corresponding to the collimating optics 40 and laser source 24). A spatial filter with a V coating can also be added to uniform the output beam profile.

[0027] In some embodiments, the remaining optics may be part of the opto-mechanical device 16. The opto-mechanical device 16 includes a beam steering assembly 44 with a two-axis galvanometer mirror driven by a rotary BLDC motor 30. The galvanometer motor control is coordinated by the MCU 18 using commands to the motor 30 based on interpreted feedback from the FSOC photodiode 27. The structure of the opto-mechanical device 16 is modular, meaning that it may be inserted inside or outside of different packages, thus allowing it to be used with multiple devices, housings, and enclosures. The mirrors of the opto-mechanical device 16 may be thin-film, multi-layer silver and / or gold coated for best response in the IR wavelength range and environmental durability. The mirrors rotate depending on the position of the motor 30, deflecting the beam toward the receiver. A final set of output optics, the outlet lens assembly 46, may be included to actively focus the power beam. Limiting the beam distance of this system to a maximum of 50 feet may eliminate the need for dynamic focusing. However, the present disclosure is not limited to this particular distance and may be used for longer free-space optical applications. A long-wave pass filter (not shown) may also be used in front of a potential lens in the FSOC optomechanical device, which includes the IR camera 28, the FSOC photodiode 27, and the FSOC LED 25. Ideally, these additional filters would not be necessary, but are listed here for completeness.

[0028] The transmitter housing 32, further shown in FIG. 2, may be a standalone structure or integrated into other devices, depending on the nature and location of its use, such as, for example, lighting fixtures, smoke detectors, security cameras, drones, and other mobile or static systems. The physical structure 32 can house all components of the transmitter 10. The mechanical structure can be designed to meet the performance and environmental requirements of the wireless power beaming system. The structure includes mechanical features and specific materials to increase conventional convective and radiative heat dissipation for the power beaming laser diode 24 and / or other high-current loads. Mechanical isolators can be utilized to stabilize the system from inherent vibration resonances associated with human movement across rooms in various structures, as well as the effects of mechanical systems such as HVAC systems. In embodiments, portions of the housing 32 can be made of any optical beam-transmitting material that is opaque in the visible wavelength range and transparent in the near-infrared wavelength range, and the entire housing 32 can also be made of this material. In this way, the user can view the housing, such as the active / internal components, rather than the exterior of a ceiling fire detector. The materials and overall mechanical construction allow it to be used in multiple environments.

[0029] Because the power beam is transmitted in a manner that is dangerous to humans and animals, the safety aspect of the system is extremely important. Therefore, embodiments of the present disclosure include a built-in safety system to prevent exposure of humans, animals, and obstacles to laser radiation above eye-safe levels, which trigger the most restrictive safety regulations. According to the present disclosure, the system is inherently safe, which is defined with reference to the system's architecture as follows: A bidirectional low-power laser beam, or FSOC channel, is established between a transmitter and one or more remote receivers, one or both of which may be mobile. The channel laser power is classified as eye-safe because it is below the maximum permissible exposure (MPE) limit, and therefore can be operated at all times without concern for adverse effects on intersecting objects. The channels propagate substantially co-directionally with the high-power laser beam, such that they are no more than 1-10 millimeters apart from the optical interface for transmission to the receiver. Due to their proximity, the low-power laser beam is blocked before the high-power laser beam is blocked, and blocking the low-power laser beam shuts down the high-power laser. As is known, laser radiation can be used for communication when a well-established line of sight (LOS) exists between the transmitter and receiver. In embodiments, if this LOS is broken due to any number of obstacles or circumstances, the high-power laser is designed to terminate within a time limit that coincides with the allowable emission limit (AEL) for compliance with the maximum permissible exposure (MPE). For Class I eye-safe classifications, the AEL is equivalent to the MPE. Because the LOS is integrated into the system's safety features and overall functionality, one cannot exist without the other. Therefore, the system can be classified as "intrinsically safe."

[0030] In an embodiment, a hardware and software implementation of the safety system includes transmitting sources, one of which is typically connected to a reliable and stable power source, and a mobile or peripheral receiver that includes minimal electrical components, implements basic digital signal processing (DSP), and is combined and integrated with a host device. This embodiment of the safety system may be explicitly designed for high-power laser beams in the near-infrared (NIR) wavelength range. The system timing can be easily adjusted to accommodate scaling safety requirements related to visible or UV light. The system premise in this embodiment may rely on fast and accurate detection of obstacles in the beam path coupled with the system latency dependency on its maximum permissible exposure (MPE) level. As further described below, additional embodiments of the safety system include hardware and software implementations that shut down high-power laser beams for other reasons.

[0031] By way of background, the current governing standards for laser safety and laser safety certification for consumer-sold products are 21 CFR Part 1040, entitled "Performance Standards for Light-Emitting Products in the United States," and IEC 60825-1, the latter of which harmonizes laser product safety in Europe and the rest of the world. In 2007, the FDA issued Laser Notice 50, which outlines the requirements that any equipment manufacturer may implement in U.S. commerce laser products that comply with the IEC 60825-1 standard. This document effectively harmonized European and U.S. certification standards and provided a "least burdensome approach." Laser Notice 50 references IEC 60825-1 to establish all system delays and detection mechanisms involved in beam operation safety. The popular ANSI Z136.1 document also provides guidelines for classifying such lasers and the safety / control measures associated with their safe operation, but it does not apply as a certification standard for comparing products seeking the above certification. Naturally, these standards are subject to change.

[0032] In typical certification governance, laser products are discretized into classes according to their power output characteristics. Depending on the pulsed or continuous wave (constant or CW) output, limit levels are usually applied, either in watts or joules (watt-seconds). The accessible emission limit value (AEL) is determined as the product of the MPE multiplied by an area factor called the limiting aperture.

[0033] For purposes of this disclosure, the laser source can operate in either CW or pulsed mode. CW operation often requires a much higher average power supply than pulsed systems. While CW systems are described below for ease of disclosure, pulsed systems with various pulse lengths can also be used. This configuration can also be implemented in a receiver device (with a lower power rating) without dynamic power control during transmitter operation. In an embodiment, the transmitter device emits high-power CW light. Simultaneously, a neighboring low-power laser beam, propagating alongside the high-power beam and parallel to it, is also emitted from separate electrical and optical components, but is positioned within a few millimeters of the high-power light source. The low-power laser beam has a much larger divergence than the high-power beam and therefore may diverge over a shorter distance than the high-power beam. For purposes of this disclosure, the operating or working distance of this system can be in the range of 1 foot to 30+ feet. This operating distance allows for a low-power photodiode assembly in the receiver with greater tolerance for placement, but with higher sensitivity requirements. The co-propagating low-power laser beams thereby create a virtual enclosure around the high-power beam over the operating distance. If the system is used at distances such as those specified above, atmospheric absorption and scattering may not pose a problem.

[0034] To increase the system's usability and capabilities, a digital data stream can be modulated onto a low-power laser beam. Modulation schemes come in a variety of forms and complexities. To build an efficient system, one can rely heavily on low overhead power consumption, or in other words, keeping the power used by all other parts of the safety system as low as possible. Therefore, the modulation scheme must be carefully selected to strike a balance. 1. Power overhead includes processing, data storage, A / D or D / A conversion, and transmission. 2. The serial data rate at which the system can interpret the information in order to properly communicate the received information to the transmitter and follow the appropriate action / command. 3. Number / type of components, i.e., reducing the number of parts, especially on the mobile receiving side, reducing the footprint and space required to implement such subsystems. 4. Multiple access, or the ability to support multiple mobile receivers with a single transmitter.

[0035] The transmitter / receiver system has a combined modulation / demodulation architecture that associates a unique frequency, timing, or signal quality with the coupled device. In this embodiment, it is possible for a single transmitter to support multiple receiver devices, differentiated by serial data rate, pulse amplitude, or timing of transmission. This is similar to how the NTIA's Spectrum Management Office or the FCC manages spectrum use, i.e., how transmitters manage wavelength use for devices. OFDM, OCDMA, or M-PPM are also acceptable modulation methods and are not excluded from this disclosure.

[0036] In its simplest form, modulation by turning a low-power laser beam on and off (on / off keying - OOK) can be used to transmit a series of bits or bit sequences, which can be thought of as a common communications protocol in intensity modulation / direct detection (IM / DD) schemes. A bit sequence library known to both the transmitter and the associated receiver provides meaning for the alternating bit sequences. OOK keeps processing overhead requirements low, increasing the effective bandwidth of the system, thereby increasing signaling speeds and resulting in reduced latency (to the point where the processing bottleneck is due to hardware / chip speed). OOK is one such modulation scheme and can be used to fully or partially satisfy communications and safety requirements. It will be apparent to those skilled in the art that other modulation schemes can be effectively used to achieve similar objectives.

[0037] The MPE / AEL level may be designed so that the shorter the exposure, the higher the allowable optical power to meet the same energy exposure level of pulsed operation. Essentially, even if the system is operating at CW output, obstacle exposure to the beam can be considered pulsed, taking into account the cutoff time achievable by the transmitter. In the upper wavelength range of IR-A and all IR-B wavelengths, the radiation is generally considered eye-safe due to its long wavelength; that is, the eye does not focus the radiation on the retina, and the radiation does not penetrate, reducing the level of the epidermis. Corneal exposure to laser light is dangerous for spot heating, and the same applies to other soft tissues at these wavelengths. Spot heating requires the application of a high-power laser source with a large output to a small surface area for a specified time. Therefore, the dangerous state of this system is temporary. Some embodiments of the present disclosure seek to meet such timing requirements.

[0038] When the disclosed system is deployed in an environment considered uncontrolled, i.e., an environment where occupants are nominally unaware of exposure to laser radiation, laser safety requirements exceed Class 1 levels. In such situations, the risk of laser radiation depends on the duration of exposure, the radiation power level, and the wavelength of the laser radiation. In embodiments, the wavelength of the power beam laser can be selected based on several factors. One such factor is the wavelength range that poses the least radiation risk to an unwitting user. In such cases, laser wavelengths that are not focused on the retina have higher exposure limits and are therefore preferred for embodiments.

[0039] In effect, the transmitter architecture acts as a watchdog for the receiver circuitry. If a predetermined period of time passes in which the transmitter receives no data from the receiver, or if a lack of bits is counted from the receiver, or if a specific bit sequence is transmitted from the receiver, the transmitter associates this absence / bit sequence with a specific message and either turns off the laser diode or reduces its power output to Class 1 levels. By providing constant feedback between the receiver and transmitter, the system not only functions safely, but also allows the receiver to be tracked. In addition to the receiver feedback data, several different voltage and / or current levels within the transmitter can be monitored for a myriad of purposes, including but not limited to: 1. [Transmitter] Laser diode front stage - voltage and current; 2. [Receiver] Downstream of the photodiode assembly - voltage and current; 3. [Receiver] Downstream of the DC / DC converter - voltage only; and 4. [Transmitter] Downstream of FSOC photodiode - voltage only.

[0040] These measurements generate all the information necessary to make decisions regarding the safety of the system in any situation. The receiver constantly updates its status to the transmitter. Any interruption in the status update, or any mismatch of the receiver to ideal parameters, will result in a reduction in the power output of the high-power laser beam. The beam cutoff timing requirements of the system may depend on the laser diode power and beam spot. Therefore, it is possible to dynamically allocate cutoff times between the transmitter and receiver as needed.

[0041] In its full implementation, this disclosure can provide fault detection and, in some examples, fault tolerance. One or more fault tolerances may be built into the hardware and software for all critical safety functions. Because the hazardous condition is only created by the transmitter, i.e., the high-power laser beam, safety-critical hardware may be contained solely on the transmitter side of the system. This critical hardware includes photoelectric sensors, operational amplifiers, processors that may be implemented in various forms, and laser diode power supplies.

[0042] Fault tolerance conditions include the following: 1. A single fault via an electrical short or open circuit in the photoelectric sensor. Such a fault will cause a zero voltage output in the case of an open circuit, a short circuit, or a floating state. In either fault condition, the processor recognizes a bit sequence that repeats over several clock cycles, automatically triggering a shutdown of the beam. 2. A single fault occurs in either the processor or the laser power supply, creating an electrical short or open circuit. In the case of an open circuit, there will be no current-carrying power supply circuit; therefore, there will be no possible mechanism for energizing the laser diode. In the case of a short circuit, the processor has the ability to check the laser diode current, as previously monitored, against the processor's trigger state in the laser power switch. The current reading is interpreted as a 1 or 0, representing current present or absent from the circuit, respectively. Its binary output can be compared with the processor's trigger state via an OR operation. This comparison may output a signal to shut off the supply to the laser diode in a dangerous situation. 3. Additional software checks for fault conditions. This requires the presence of several assigned expected signals before the laser will begin delivering high power. Absence or non-nominal values ​​of these specific signals will cause the laser diode to remain off.

[0043] In embodiments, the safety optoelectronic components are designed for specific detection at IR wavelengths, which can be different from the high-power laser wavelength. By using a photodiode / LED pair that operates at the same wavelength, communication can be achieved over a nearly 180-degree full-angle field of view (FOV) without the need for additional focusing or adjustment optics.

[0044] The safety system operation and implementation methods described herein also allow for communication of system status data to any remote processor, determinable via a user interface (UI). This can further be used to correct potential connection issues by manually removing obstructions or interruptions. In this embodiment, the absence of a signal for a specific number of bits (time) can lead to a UI message being sent notifying the user of the current fault. Message types are interpreted from data received from the low-power laser beam, the FSOC link. While greatly simplified to use FSO signals, the internal electrical modulation or messages can be much more complex without burdening the processor. This improves system uptime, overall functional efficiency, and ease of use.

[0045] Returning now to the receiver first shown in FIG. 2 , as shown in FIG. 3 , as part of the receiver or host structure, i.e., the device in which the receiver 60 is installed, the receiver 60 is comprised of a photodiode assembly 62 including a photodiode array 63. The photodiode array 63 or diodes is not limited to diode-based technology and may be implemented with alternative technologies that exist now or are developed in the future and can perform similarly. Additionally, the photodiode assembly 62 is not limited to wireless power transfer embodiments. The photodiode assemblies of the present disclosure may be readily adapted to a variety of other embodiments where efficient transfer of light to electrical current and voltage is desired, such as applications requiring precise alignment, applications involving optical signals in extreme environments, or similar embodiments.

[0046] In an embodiment, the photodiode assembly 63 receives power in the form of current and voltage and may be supported by a photoelectric converter 64, such as a boost converter, that converts the voltage and current into a voltage and current usable for battery charging, a battery charge manager 66 that controls the flow of current and bias voltage applied to a rechargeable power storage device or battery 68, and high photoelectric conversion and associated power electronics circuitry that converts the voltage appropriately via a low power processor / controller 70. The processor / controller samples the voltage and current outputs from both the photodiode assembly 62 and the battery charge manager 66, encodes and modulates / demodulates digital and analog signals to and from a remote transmitter unit, pushes transmitted user information from a local buffer onto an RF connection (which may be Bluetooth, WiFi, or similar), monitors the temperature of the photodiode assembly heat sink via a temperature sensor 72, and communicates its status to the remote transmitter via an antenna 73 or low power laser beam.

[0047] To improve the usability of the system in chaotic and unpredictable user environments, one or more visual UI indicators, such as an RGB status LED 75, can be added. In an embodiment, the main UI 75 displays visual indicators with different or similar states, but not identical states. Each state simply represents the overall state of the receiver, the transmitter, or both. Representing multiple states via such visual indicators allows the user to interact with the system more efficiently. In an embodiment, a small circle with a dot in the center represents a visual indicator and one state. A small circle with a flashing dot represents a second state. A circle without a dot represents a third state. A flashing circle represents a fourth state. Various colors can be used for the circle and dot in various combinations to represent additional states. In these aforementioned chaotic environments, visual indicators provide user knowledge cues. In one such implementation, the second state could mean that there is a partial or complete blockage in the line of sight between the transmitter and receiver. The first state represents the device engaged in wireless power transmission, the third state represents the transmitter attempting to find the receiver, and the fourth state represents the transmitter and receiver are not synchronized.

[0048] Further receiver 60 elements include: a heat sink / spreader element 74 capable of controlling the thermal characteristics of the photodiode assembly when subjected to a high power laser beam; an IR communication photodiode 76 disposed with the photodiode assembly 63; an IRLED 78 co-located with a photodiode assembly 63 and a compound parabolic concentrator (CPC) mirror element 80; an anti-reflection (AR) coated, scratch-resistant window surface (not shown) at the collector entrance on mirror element 80; a lithium ion or lithium polymer battery housing (not shown) for modular attachment of battery 68 or incorporation into a receiver rechargeable unit; A device housing (not shown) for packaging and / or containing the above elements. In an embodiment, the receiver device may be integrated into a larger device used in the consumer electronics, medical, or industrial industries.

[0049] The photodiode assembly 63 can capture the high-power light beam and convert it into electrical power in the form of current and voltage. The power electronics circuit can use the output voltage and current from the photodiode assembly and convert it through a voltage converter 64 to a voltage applicable to charging the battery, depending on the battery or rechargeable load impedance. In some embodiments, the voltage converter 64 may not be necessary because the raw output of the photodiode assembly 63 may fall within the operating voltage and current of the connected energy storage device 65. The power electronics circuit can also track the input impedance of the photodiode assembly 63 and control the voltage and current based on this device impedance in the form of maximum power point tracking (MPPT). The battery charge management circuit 66 can be responsible for controlling the current and voltage to the rechargeable storage device 68 based on the optimal charging cycle for each configuration of the rechargeable storage device. The current and / or voltage output by the battery charge management circuit 66 can be measured by a current / voltage meter 67. The output from the photodiode assembly can also be used to temporarily power other active elements of the receiver system.

[0050] A processor or controller 70, such as an ARM Cortex or similar processor, can collect data from the photodiode assembly 63 and voltage converter 64 output voltage information and, via an encoder / decoder 77, encode that information onto a carrier wave via a modulation process by an IR transmitter 82. The voltage feedback information provides for transmitter beam landing accuracy and interpretation of emergency or hazard detection signals. The processor 70 can also demodulate any received transmitter-generated signals, decode that information, and process and execute any proposed actions resulting from that information. The processor 70 further stores information, such as system efficiency and health information and statistics, in a local buffer (not shown) for transfer to a remote storage location based on the timing of the specific information needed, for subsequent push to a Bluetooth, WiFi, or other RF connection.

[0051] An IR photodiode 76 converts the incoming IR low-power laser beam signal into electrical pulses that are amplified and sent to the processor or controller 70. An IR LED 78 converts the electrical pulses into optical signals for transmission outside the receiver mechanical structure with a wide FOV. An opto-mechanical device housing (not shown), such as a window element over the photodiode assembly 62, connected to the input terminals of the CPC device 80, seals the sensitive opto-mechanical device surface, ensures a continuous exterior mold line (OML) of the receiver / structure, and ensures a preferred optical path for the incoming and outgoing light.

[0052] As further illustrated by the lens stage in FIG. 13, the window used to seal the entrance can also have dispersive properties near its outermost surface to prevent back reflections within the CPC 80 from focusing into the external environment. Focusing properties near its innermost surface can also aid in light collection at the exit. Such properties can be achieved with the placement of a Fresnel lens 600, as further illustrated by FIG. 12. The Fresnel lens 600 focuses incident light onto the photodiode assembly 602 and diffuses radiation reflected within the CPC 80 that is not captured by the photodiode assembly. More specifically, the Fresnel lens or other lens 600 can have a positive focal length to concentrate incident radiation at the entrance onto the exit aperture and photodiode assembly 602. At the same time, the innermost surface of the Fresnel lens can have a negative focal length to diffuse reflected radiation within the CPC 80 over a wider area. The divergence of light from the receiver entrance further enhances the laser safety of the overall system. As shown in FIG. 13, one or more Fresnel lenses 600 are sandwiched between two primer layers 602 and 604, two thermally cured dip coats 606 and 608, and two hard anti-reflective stacks 610 and 612, the outer surfaces of which are coated with a superoleophobic / hydrophobic top coat 614.

[0053] As further described below with reference to FIGS. 4A and 4B , a CPC mirror 80 is used and sized to fit the enclosure in which the receiver 60 is placed. The CPC mirror 80 may be used for pure light collection, to increase the receiver 10's FOV light capture, and for improved, tuned, and uniform illumination of the photodiode assembly 63. The inner surface of the mirror 80 may be coated with a thin layer of deposited metal to maintain the maximum possible beam output. In the embodiment shown in FIG. 4B , the CPC mirror 80 may be truncated or extended at a shallow angle 81 toward the entrance to further increase the system's FOV. A shallow angle or chamfered surface may be used to extend 360 degrees around the CPC or where application is less of a priority. A modular battery housing (not shown) may also be used, including a mechanical structure to house a compact energy storage device 68, including, but not limited to, lithium-ion or LiPo battery cells, a capacitor bank, or a super battery, that can be configured and electrically connected to a complete receiving device.

[0054] The receiver consists of two major subsystems: the power reception subsystem and the communications subsystem. The functionality of the subsystems can be designed to be modular with minimal interfacing requirements between modules. The goal of modular system design is to allow for a power-only implementation or a communications-only implementation, or both. In a modular design, interfaces (i.e., subsystem IOs) that perform functional tasks based on inputs from others can be reprogrammed to another host system or left open. The technical implication of this is the ability to incorporate just the FSOC subsystem or the power reception chain into multiple upstream systems.

[0055] The receiver components can be designed with simplicity and a small form factor in mind. Integrating the receiver into a consumer electronics product can set requirements for size, power usage, and power density, which can later be developed into standards for such devices. To reduce board / device space and power consumption, the electrical circuitry can be kept as simple as possible. The voltage converter 64 can play a role in reducing device size. The boost converter 64 can be responsible for increasing the transducer's output voltage to the appropriate battery charging voltage. All converter stages may also require power usage (as they are active switching components), which reduces the overall efficiency of the receiver 10. To reduce efficiency losses at this stage to less than 8%, the boost converter 64 can use maximum multiple power point tracking (MPPT), similarly implemented in solar cell systems but not known for use in IR, in laser-based systems within the first converter stage. The MPPT architecture is a "test and adjust" type that probes the required input impedance to ensure the circuit and device impedance are matched, thereby maximizing the power delivered by the photodiode assembly.

[0056] An additional battery charge manager 66 may be used to accommodate a complete charge cycle for lithium-ion, lithium polymer, or other battery chemistries. If the host receiver battery or storage device is not lithium-based, a charge manager is not required. A bulk / storage capacitor 84 may also be used between the photodiode assembly 62 and the voltage converter 64 to provide filtered power to the voltage converter 64.

[0057] The receiver 60 design may also require leads to be as short as possible to minimize lead resistance and distributed inductance, i.e., for transient charging cycles. The voltage output of the photodiode assembly, an optical-to-electrical converter embodiment, may be sampled by the processor 70 and considered part of the safety subsystem. The sampled data can be stored and forwarded to an encoder / decoder 77 to encode a bit sequence at a predetermined carrier frequency transmitted by the FSOC LED 78. One unique aspect of this architecture is that the receiver 60 transmits a simple bit stream to the transmitter 10, transmitting messages that require little message overhead. The processor in the transmitter 10 performs the heavy lifting in terms of interpreting the bit sequence.

[0058] Finally, the core logic of the receiver 60 may consist of a processor 70. The processor 70 can interpret feedback from the IR transceiver 82 and the encoder / decoder 77. The receiver 60 may also incorporate a communications system that is an improvement over the IrDA (Infrared Data Association) standard. Because the IrDA standard is designed to operate between 1 cm and 1 m, a wider range is necessary to make the presently disclosed technology more useful and distinctive. At the same time, ambient light sources may contaminate the sensor and cause interference with the small optical input signal. To overcome this issue in some embodiments, it may be desirable to increase the magnification of the IRFSOC light with a hemispherical lens on the photodiode receiver 76 and design a narrow bandpass filter at the backend of the photodiode receiver. The bandpass filter allows only a specific band of wavelengths through while suppressing both external power sources in the DC environment and sporadic external power sources. Driving the FSOC LED at its maximum supply level may further increase the distance while maintaining eye safety limits.

[0059] The optical architecture of the receiver 60, as shown in Figures 4A, 4B, and 13, may consist primarily of a scratch-resistant, hydrophobic, and possibly oleophobic, anti-reflection (AR) coated optical window 90. The optical window 90, known as a lens stack, interfaces with the receiver in which the receiver 60 is embedded. The external optical interface between the receiver and the surrounding environment may be flush to avoid scratches and damage that can occur on offset or raised (or domed) surfaces. The window itself is AR coated to provide scratch resistance and hydrophobic / oleophobic properties. This maintains a clean, IR-transmitting surface at the entrance to the CPC, ensuring beam path fidelity to the receiver's photodiode assembly while preventing the accumulation of dirt, moisture, and grime on the optical surfaces.

[0060] As previously mentioned and further shown in Figures 4A and 4B, the CPC mirror 80 can focus the incident light at its entrance onto the photodiode assembly 63 at its exit. The photoelectric converter may be combined with the FSOC LED 78 and IR photodiode 76 of Figure 3. The CPC mirror 80 may be uniquely shaped as a light collector, substantially increasing the overall system field of view (FOV). One advantage of the CPC mirror is that it eliminates the need for a condenser lens to focus the light onto the photodiode. The interior walls of the CPC are coated with 100-300 nm of silver, gold, or aluminum. Depending on the embodiment, an environmental protection layer may be included to extend component life. The key to the coating is to ensure maximum reflectivity across the entire IR beam wavelength range. Losses due to reflection or absorption at this interface may be less than 1%. The overall shape of the CPC mirror 80 can be based on the intersection of two parabolas and can have a cone or bowl-like appearance. As shown in FIG. 4B, the CPC may also be truncated on the entrance side of the mirror to allow for tapering of the edge 81 at the connection to the OML or to allow for an increased system FOV.

[0061] The photodiode assembly 63 can be integrated into the base of the CPC mirror 80 to ensure maximum exposure to incident light. As mentioned above, a NIRAR coating may be applied to the top window surface 90, which is flush with the device's exterior. To withstand stochastic user environments, a hard coat may need to be maintained on the top surface to reduce the likelihood of surface scratches, which could degrade the surface and therefore the overall effectiveness of the system. Additionally, fingerprints and other environmental contaminants may be present during the component's lifetime. A hydrophobic surface helps minimize surface contamination. Hydrophobic layers may be implementable via temporary and permanent coatings during manufacturing and use. Similar integration can be used for oleophobic coatings. Thus, users can "touch up" optical surfaces as needed, which may lead to improved performance. The IR LED 78 and IR PD 76 form the basis of the receiver 60's communications and safety subsystem. As mentioned above, the FSOC low-power laser beam propagates alongside the high-power beam, forming a virtual enclosure around the high-power beam. Therefore, the FOV of the component of the high-power laser beam must be equal to or greater than the FOV of the component of the high-power laser beam to ensure that the high-power laser beam remains contained within the optical cone of the communication link with the FSOC low-power laser beam and maintains a communication link with the transmitter 10 at all possible power beam positions. In various embodiments, either active or passive lenses or optical materials can be added to the beam path of the low-power laser beam to further converge or diverge the FSOC beam and ensure such coverage for the power beam. The FSOC optoelectronic components are positioned as close as possible to the receiving photodiode assembly. These embodiments may also include applications with transmission range requirements.

[0062] The overall physical size of the integrated receiver may be designed to be compatible with the environment in which it will be used. For many mobile consumer electronics applications, this means dimensions in the range of 10 mm or less per side. However, these dimensions are merely exemplary, and the present disclosure is not limited to such dimensions. Still, maintaining a small volume may allow the technology to be integrated into a variety of hardware devices. The overall support structure (not shown) for the CPC mirror 80 may be centered around stabilizing the CPC / photodiode assembly. The CPC itself may be fabricated separately or cut from a cube of optical material. Integration of the CPC and photodiode may occur simultaneously with or before integration into the receiver.

[0063] Turning now to FIGs. 5-11, we turn to the receiver photodiode assembly 63. The photodiode assembly 63 may be a back-contact photodiode assembly specifically designed for high-power laser light-to-electricity conversion. As further described below with reference to FIGs. 9A and 9B, the back-contact photodiode assembly may be comprised of multiple photosensitive regions arranged in a pi wedge to maximize pi wedge photon exposure, reduce component footprint, and achieve uniform response from each photodiode within the pi wedge. The band structure of the device is determined by the In bandgap bandgap formed therefrom. x Ga 1-x By manipulating the composition of As semiconductor materials, they can be specifically designed to optimize narrow wavelength absorption; that is, "x" is carefully chosen so that light is efficiently (>95%) absorbed at thicknesses of 2-5 μm, while the bandgap is only slightly smaller than the photon energy, maximizing power conversion efficiency. The back contact, which serves as both the electrical and thermal path, can be sized to have minimal series resistance, sufficient heat capacity, and a large surface area for heat dissipation and mass production. Each of these aspects is discussed in further detail below.

[0064] As shown in Figure 5, the substrate top surface 100, i.e., the surface onto which light is incident, is a solid (unobstructed) bulk, lightly doped InP substrate. As used herein, lightly doped means that the impurity concentration is <10 16 atoms / cm 3 To prevent the incident radiation from reflecting off the surface of the InP, the top substrate layer 100 can be coated with a thin anti-reflective layer 102, the thickness of which corresponds to a quarter wavelength of the intended incident radiation. The anti-reflective (AR) layer 102 is formed by the product of the refractive indices (n air ×n semiconductor The substrate 100 may be Si3N4 or another compound with a refractive index close to the square root of . The substrate 100 and underlying layers may be sized based on the absorption coefficient of light between 1400 and 1600 nm in the InP / InGaAs material. The penetration depth of light as a function of wavelength is further shown in FIG. 6. As shown in the plot, within the active InGaAs region 200, most of the light is completely absorbed within a few microns.

[0065] An additional consideration regarding the active region of the photodiode assembly 63 is the size or area of ​​the depletion width, where the imaged electrons and holes diffuse into the n+ and p+ regions due to the electric field established within this region. Within this active region, the electric field can be so strong that electrons are separated to create electron-hole pairs. The corresponding energy required for separation is known as the bandgap energy. Combining knowledge of the bandgap energy with the wavelength of the incident light may allow for optimization of the atomic concentration of the material. Between the substrate layer 100 and the InGaAs layer 104 is a heterojunction buffer layer 106, as further shown in FIG. 7, which prevents electrons and holes from leaking back into the InP substrate layer 100. In other words, the 106 buffer heterojunction performs photocarrier collection in one direction (only the bottom n+ / p+ electrode region 108, not the top InP layer). This is an ideal situation for achieving efficient light-to-electrical energy conversion.

[0066] As further shown in FIG. 8 , electron-hole pairs are generated in the active n+ / p+ electrode regions 108 as a function of incident light. Therefore, a PIN structure can be formed via alternating n+ / p+ electrode regions 108 with a small width between them and the electrode regions 108. With a short separation distance, free electrons 114 in the active regions are swept toward the n+ regions, and holes 116 in the active regions are swept toward the p+ regions, generating a stable current. The n+ and p+ electrode regions 108 can be configured such that a conductive path exists to the interdigitated back contacts 110. A thin passivation layer 112 between the back contacts can prevent the electrode regions from directly shorting out. The passivation layer 112 can be made of several suitable materials (e.g., Cu, Al, Ag, etc.).

[0067] As previously mentioned, each of the back contact, finger-like structure configurations interdigitates based on the spacing between the p+ / n+ electrode regions 108. This can improve collection efficiency by having evenly spaced, distributed periodic structures on the backside of the photodiode assembly 63. The back contact can be a microstructure formed into pie-shaped sections to reduce series resistance. In the embodiment shown in FIG. 9A, the alternating interdigitated fingers 210 and 212 are substantially straight. In a second embodiment shown in FIG. 9B, the interdigitated fingers 210 and 212 can be shaped to match the radius of curvature of the overall device. For example, as shown in FIG. 9B, each pie-shaped section 250 has interdigitated fingers that are slightly curved to fit the circular shape of the photodiode assembly 63, with smaller interdigitated fingers toward the central region 252 and substantially longer outer regions 254. Shaping the p+ / n+ regions so that they are adjacent to the back contact electrodes conforms to the circular shape of the photodiode assembly 63, improving overall collection efficiency and power conversion efficiency.

[0068] The anode 200 is connected in series with the cathode 202 ccw (counterclockwise) around the photodiode assembly 63. The serial connection allows the threshold voltages generated by each individual section to be added, thereby generating a total voltage at the device terminals. The sections of the assembly can be further monitored by measuring the output voltage, as shown by monitoring point 400 in Figure 11, to determine the relative illumination of each section. This voltage information is transmitted to the transmitter to aid in improving beam pointing adjustments. Fine finger structures are positioned directly beneath the p+ / n+ electrode regions 108, where maximum photo-electron collection within the active region can occur. The interdigitated design allows for finely spaced electrode finger placement to set up a continuous field structure spanning the n+ / p+ electrode regions 108. Finger length can be minimized to reduce series resistance, providing a low-resistance connection from the section to the periodic electrode rail section. The backside can provide sufficient isolation 206 to prevent shorting of the fine finger structures and gap filling with silicone polymer, h-BN, or similar electrically resistive materials. Note that the top InP surface 100 does not need to be etched or divided into discrete sections such as a back contact pattern, as this is not dependent on the optoelectronic performance of the necessary bulk substrate 100 of the present invention.

[0069] The photodiode assembly 63 of the present disclosure can be integrated in a variety of forms. One such method, as further shown in FIG. 10 , includes integration onto a PCB (printed circuit board) so that the anode and cathode are routed from the device as traces. In this embodiment, the device may be used in a variety of forms, such as a laser-based wireless power transfer system to power a co-located device, a receptor element used in sensors used in applications involving high-power lasers, a fine-tuning or alignment sensor when individually wired based on feedback from individual sections, or multiple other optical-based systems. Further integration into complex or standalone systems is also possible based on the application.

[0070] In Figures 10 and 11, the InGaAs assembly / chip 300 may be bonded to a small portion of a copper film 302. The bonding area may cover the entire back surface of the photodiode assembly / chip 300, with a small electrically insulating layer (not shown) applied between the copper film and the back electrode contact. The copper film 302 may be bonded to a heat sink 306 and / or blank copper inlay 308 on the PCB by a thermally conductive epoxy layer 304 (the thickness of which may vary). The anode electrode can exit the side of the chip and be directly connected to the PCB via a trace or wire. Therefore, the disclosed device can maintain a compact form factor to increase modularity and facilitate component integration via electrode pads. The disclosed device can also allow for parallel wiring depending on the load requirements and input expectations for downstream circuitry.

[0071] The overall operation of the power transfer device can be described as follows: When the receiver recognizes that its state of charge ("SOC"), power supply voltage, or several other indicators are below a predefined threshold, it pings its built-in wireless power transfer hardware to confirm and wake up the network connection. The IR LED on the front of the receiver begins to periodically emit light as a "beacon signal" to nearby transmitters. The beacon signal consists of a short digital data stream modulated onto a carrier signal and contains the device's unique ID (device name, manufacturer, revision, type, etc.), an indication of the state of charge (SOC), and an FSOC signal containing information for the transmitter to generate a lock ID. The lock ID is generated within the transmitter as a location-based record of the receiver's last known location (coordinates relative to the beam steering subassembly) and is verified by the receiver via the FSOC link. In another embodiment, the receiver can use a built-in RF antenna to communicate status information to nearby transmitters. The transmitter can use the built-in RF antenna to check the receiver's SOC, battery voltage, etc., and determine the receiver's ability to participate in the wireless power beaming process. In an embodiment, the transmitter may choose not to engage a receiver in a wireless power beaming (beam steering) process if the transmitter determines that it would be beneficial due to the receiver's low battery. The transmitter may also refuse to engage with a particular receiver if device priorities are set as follows: 1) Other more important units require more power than the transmitter can provide to the requesting device; 2) The transmitted device ID is determined by the target transmitter to be unrepairable (e.g., the device's firmware or hardware is out of date or unauthorized); or 3) There is a set of recognized error conditions at the receiver. The transmitter then releases the connection to the receiver, allowing other receiver functions to take priority.

[0072] Meanwhile, the transmitter monitors its IR photodiode for a beacon signal and can process the receiver's digital information when its photodiode is activated by the beacon signal. When a beacon signal is detected, the transmitter's IR camera switches from an "idle" state to an "active" state and begins locating the IR beacon from the receiver. The time at which the IR camera changes state, i.e., from active to idle only after a predetermined "no detection" period has elapsed, is approximately 30 seconds after the transmitter's IR photodiode last detected a signal (a time period, i.e., a longer or shorter time, without changing the method of this embodiment).

[0073] After the transmitter's IR camera identifies the approximate location of the beacon signal, a continuous communications link can be established via FSOC. The transmitter's IR low-power laser diode begins performing a localized scan pattern near the identified receiver's approximate location. When that scan is picked up by the receiver photodiode, a communications link / handshake is established. The predetermined period for establishing the link is called the "handshake event time." As mentioned above, the low-power transmitter's IR beam is aligned with the transmitter's high-power beam. The transmitter's low-power laser beam creates a larger spot size at the receiver's beacon photodiode than the transmitter's high-power beam at the receiver's output beam photodiode.

[0074] When a handshake event occurs, the transmitter's high-power laser beam is swept across a local area by the transmitter's low-power laser diode in a low-power setting to find the power of the beam emitted by the receiver's photodiode. The low-power laser diode may change its output spot based on its state. This may involve electrically activated optics, such as a liquid lens. The receiver's LED reports back power data to the transmitter at microsecond intervals over the established communication channel. When the transmitter's IR power beam crosses the local maximum and returns, as reported by the receiver's IR LED, localization can be considered complete and the high-power beam supply can be increased to match the device type. The low-power laser beam maintains continuous communication with the transmitter's photodiode, providing information on transfer efficiency, received power, SOC, and current and voltage readings from the power photodiode.

[0075] Loss of reported information lasting longer than the predetermined safety shut-off time causes an internally generated danger warning signal to the transmitter laser driver to reduce beam power to a safe level. End-of-beam activity is signaled directly by the receiver's IR LED (through a lack of data or a specific bit sequence) and interpreted by the transmitter IR photodiode. The duration of the end-of-beam activity signal is no longer than the predetermined safety shut-off time.

[0076] If beam operation terminates, for example if link margin efficiency or voltage / current statistics from the receiver power photodiode assembly are violated, the transmitter will attempt to locate again using the receiver's last known position and the lock ID stored by the transmitter at the time tracking was requested, against the receiver power photodiode. The same transmitter scan pattern is used along with the incident power reported by the receiver's IR LED.

[0077] If the transmitter or receiver electronics determine an internal condition that prevents nominal operation (relative to an interruption in external LOS), the transmitter / receiver communicates this to the receiver / transmitter and enters fail-safe mode. No further communication or power transfer occurs until the fault is resolved. Faults are classified by the following categories: internally resettable, externally resettable, user equipment (UE), replacement, etc. An indication that either the transmitter or receiver is in fail-safe mode is visually indicated by a flashing LED in an error message sent to the UE. While the presently described method of operation is described in the context of the specifically disclosed power transfer system described herein, the method of operation is not limited to the device just described and can be implemented with different types of power transfer devices according to the present disclosure.

[0078] In an embodiment, a transceiver assembly for a wireless power transmission system includes a transceiver system, the transceiver system comprising: a photodiode assembly configured to receive the high power laser beam from the transmitter and convert the high power laser beam into electrical energy; a voltage converter configured to adjust an input impedance based on a voltage measurement of the photodiode assembly to maximize power transfer from the photodiode assembly to an energy storage device electrically coupled to the voltage converter, wherein adjusting the input impedance increases charging efficiency of the energy storage device; the transceiver system comprising a light emitting diode and a photodiode configured to enable free space optical communication with the transmitter; The light emitting diode emits a signal to the transmitter indicating its presence and location at least when the energy storage device needs charging.

[0079] In embodiments, the light emitting diode is further configured to transmit, using the photodiode assembly, a signal including information regarding alignment of the high power laser beam. In embodiments, the light emitting diode is further configured to transmit a signal including information regarding the amount of optical power delivered to the energy storage device. In embodiments, the light emitting diode is further configured to transmit a signal including information regarding the voltage of the energy storage device. In embodiments, the light emitting diode is further configured to transmit a signal including information regarding a device in which the transceiver system is implanted.

[0080] In an embodiment, the light emitting diode and the photodiode are arranged to be located as close as possible to the photodiode assembly in the spatial plane of the photodiode assembly.

[0081] In an embodiment, the energy storage device is one or more of a battery, a bank of capacitors, and a bank of supercapacitors.

[0082] In an embodiment, the voltage converter also provides power directly to a non-energy storage device.

[0083] In an embodiment, the cathode of the photodiode assembly is configured to be electrically isolated from ground for the transceiver system so as to provide a return path for low noise operation of the transceiver system.

[0084] In an embodiment, the leads of the photodiode assembly are configured to reduce resistive and inductive losses.

[0085] In an embodiment, the transceiver system further includes a capacitor upstream of the energy storage device, wherein the capacitor is configured to reduce rapid rises and falls in current or voltage at the terminals of the energy storage device.

[0086] In an embodiment, the first traces of the light emitting diode and photodiode and the second traces of the photodiode assembly and voltage converter are configured to be physically separated from one another to prevent coupling of electrical noise between the first traces and the second traces.

[0087] In an embodiment, the transceiver system further includes a temperature sensor configured to indicate a temperature surrounding the transceiver system exceeding a predetermined limit, and the light emitting diode emits a signal including a message to the transmitter to stop transmitting the high power laser beam when the temperature exceeds the predetermined limit.

[0088] In an embodiment, the transceiver system is configured to be integrated into a compact device.

[0089] In an embodiment, the photodiode assembly comprises: a substrate layer having a light-exposed surface and an internal surface; an anti-reflective layer adjacent to the light-exposed surface and configured to prevent incident light from reflecting off the surface of the light-exposed surface; a heterojunction buffer layer located adjacent to the inside; an active region disposed adjacent to the heterojunction buffer layer and configured to convert photons from incident light into separated electron-hole pairs, the heterojunction buffer configured to prevent the electrons and holes of the released electron-hole pairs from migrating toward the substrate layer; The photodiode assembly a plurality of n+ and p+ electrodes disposed adjacent the active region, configured in an alternating pattern with a gap between each n+ electrode and each p+ electrode, and further configured to receive and generate current from the movement of electrons and holes, thereby providing an electrical path for the current, and providing a thermal path; The alternating pattern includes a series of pie-shaped sections; Each pie-shaped section has narrow ends adjacent to central regions of n+ and p+ electrodes; Each pie-shaped section is formed by alternating rows of n+ electrodes and rows of p+ electrodes; The transceiver system further comprises: an anode back contact configured to align with a portion of the alternating pattern corresponding to the rows of n+ electrodes; and a cathode back contact configured to align with a portion of the alternating pattern corresponding to the rows of p+ electrodes.

[0090] In embodiments, the receiver further includes a thin-film heat dissipation material disposed in contact with the non-illuminated side of the photodiode assembly and configured to conduct heat away during high-intensity exposure of the photodiode assembly. In embodiments, the substrate layer has an etch pitch density configured to avoid scattering of incident light. In embodiments, the heterogeneous buffer layer is configured to include a non-uniform concentration of material throughout to form a more matched structure. In embodiments, a current is measurable at one or more of the anode back contact and the cathode back contact of each pie-shaped section. The measured current at each pie-shaped section corresponds to a relative illumination intensity from the high-power laser beam at each pie-shaped section, and the measured current at each pie-shaped section is output as a signal to the transmitter to adjust the direction of the high-power laser beam.

[0091] In embodiments, the laser beam source further includes a compound parabolic concentrator mirror having a curved interior wall defining an entrance aperture to an exit aperture and connecting the entrance aperture to the exit aperture. The entrance aperture is larger than the exit aperture, and the interior wall focuses a majority of the laser light incident on the entrance aperture onto the exit aperture. The photodiode assembly is disposed adjacent to the exit aperture and configured to receive the laser light exiting the exit aperture.

[0092] Having thus described different embodiments of a wireless power transmission system and methods of operating the same, it will be apparent to those skilled in the art that certain advantages of the described methods and devices have been achieved. In particular, it should be understood by those skilled in the art that the transceiver assembly of the wireless power transmission system can be implemented and operate in a variety of ways different from those described herein using different types of hardware, software, and combinations thereof. Furthermore, various modifications, adaptations, and alternative embodiments thereof can be made within the scope and spirit of the present disclosure.

Claims

1. 1. A transceiver assembly for a wireless power transfer system, comprising: the transceiver assembly comprises a transceiver system; The transceiver system comprises: a photodiode assembly configured to receive a laser beam from a transmitter separate from the transceiver system and convert the laser beam into electrical energy; a voltage converter configured to adjust an input impedance based on a voltage measurement of the photodiode assembly to maximize power transfer from the photodiode assembly to an energy storage device electrically coupled to the voltage converter; The transceiver system comprises: a light emitting diode and a photodiode configured to enable free space optical communication with the transmitter; the light emitting diode transmits a signal to the transmitter indicating the presence and location of the transceiver system at least when the energy storage device requires charging; A transceiver assembly, wherein the photodiode assembly receives the laser beam from the transmitter to charge the energy storage device based on a ranked priority between the transceiver system and other transceiver systems.

2. 10. The transceiver assembly of claim 1, wherein the light emitting diode is configured to emit an information-bearing signal using the photodiode assembly.

3. 2. The transceiver assembly of claim 1, wherein the light emitting diode and the photodiode are arranged on a spatial plane of the photodiode assembly.

4. 10. The transceiver assembly of claim 1, wherein the energy storage device is one or more of a battery, a bank of capacitors, and a bank of supercapacitors.

5. The transceiver assembly of claim 1 , wherein the voltage converter further provides power directly to a non-energy storage device.

6. 10. The transceiver assembly of claim 1, wherein the cathode of the photodiode assembly is configured to be electrically isolated from ground of the transceiver system.

7. 10. The transceiver assembly of claim 1, wherein the leads of the photodiode assembly are configured to reduce resistive and inductive losses.

8. the transceiver system further includes a capacitor upstream of the energy storage device; 10. The transceiver assembly of claim 1, wherein the capacitor is configured to reduce rapid rises and falls in current or voltage at the terminals of the energy storage device.

9. 2. The transceiver assembly of claim 1, wherein first traces of the light emitting diode and the photodiode and second traces of the photodiode assembly and the voltage converter are configured to be physically separated from one another.

10. the transceiver system further comprises a temperature sensor; 10. The transceiver assembly of claim 1, wherein the light emitting diode emits a signal indicative of a temperature in an area surrounding the transceiver system.

11. 11. The transmitter / receiver assembly of claim 10, wherein the transmitter is configured to cease transmitting the laser beam when the temperature exceeds a predetermined limit.

12. The transceiver assembly of claim 1 , wherein the transceiver system is configured to be integrated into a device.

13. The photodiode assembly includes: a substrate layer having a light-exposed side and an interior side; an anti-reflective layer adjacent to the light-exposed side and configured to prevent incident light from reflecting off the surface of the light-exposed side; a heterojunction buffer layer disposed adjacent to the interior facing side; an active region disposed adjacent to the heterojunction buffer layer and configured to convert photons from incident light into free electron-hole pairs; the heterojunction buffer layer is configured to prevent electrons and holes of the released electron-hole pairs from migrating toward the substrate layer; The photodiode assembly includes: a plurality of n+ electrodes and p+ electrodes disposed adjacent the active area and configured in an alternating pattern with a gap between each n+ electrode and each p+ electrode, the plurality of n+ electrodes and p+ electrodes further configured to receive and generate current from movement of electrons and holes, provide an electrical path for the current, and provide a thermal path; the alternating pattern includes a series of pie-shaped sections; each said pie-shaped section having a narrow end adjacent a central region of said n+ electrode and said p+ electrode; each pie-shaped section is formed by alternating rows of the n+ electrodes and rows of the p+ electrodes; The transceiver system further comprises: an anode back contact configured to align with a portion of the alternating pattern corresponding to the rows of the n+ electrodes; a cathode back contact configured to align with a portion of the alternating pattern corresponding to the rows of the p+ electrodes.

14. 14. The transceiver assembly of claim 13, wherein the transceiver system further comprises a heat dissipating material disposed in contact with a non-illuminated side of the photodiode assembly and configured to conduct heat away.

15. 14. The transceiver assembly of claim 13, wherein the substrate layer has an etch pitch density configured to avoid scattering of the incident light.

16. 14. The transceiver assembly of claim 13, wherein the heterojunction buffer layer includes a non-uniform concentration of material throughout and is configured to form a more lattice-like and conformal structure.

17. the current is measurable at one or more of the anode back contact and the cathode back contact of each pie-shaped section; the measured current of each pie-shaped section corresponds to a relative illumination intensity from a high-power laser beam of each pie-shaped section; 14. The transmitter / receiver assembly of claim 13, wherein the measured current in each pie-shaped section is emitted as a signal to the transmitter to adjust the direction of the high-power laser beam.

18. the transceiver assembly further comprising a compound parabolic concentrator mirror defining an entrance opening and having a curved interior wall connecting the entrance opening to an exit opening; the inlet opening is larger than the outlet opening; the interior wall focuses a majority of the laser light incident on the entrance opening to the exit opening; 2. The transceiver assembly of claim 1, wherein the photodiode assembly is positioned adjacent to the exit aperture and configured to receive laser light exiting the exit aperture.

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