WO2022023946A1 - White-light illumination and near-infrared communication system and method based on multiple pathway visible-light - Google Patents

Abstract

A transmitter (106) for illuminating with visible light and for broadcasting data with near-infrared light includes a single light source (302) configured to generate an optical beam (304) having a first wavelength in the ultraviolet to visible spectrum, a first phosphor (310) configured to receive the optical beam (304) and to generate a visible light beam (316), and a second phosphor (312) configured to receive the optical beam (304) and to generate a near-infrared, NIR, beam (314) having a second wavelength, larger than the first wavelength. The first wavelength is between 400 and 750 nm and the second wavelength is between 750 nm and 2.5 µm.

Description

WHITE-LIGHT ILLUMINATION AND NEAR-INFRARED

COMMUNICATION SYSTEM AND METHOD BASED ON MULTIPLE

PATHWAY VISIBLE-LIGHT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/057,023, filed on July 27, 2020, entitled “MULTIPLE PATHWAY VISIBLE- LIGHT FOR WHITE-LIGHT ILLUMINATION AND CONVERTED NEAR-INFRARED OPTICAL UPLINK,” the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

TECHNICAL FIELD

[0002] Embodiments of the subject matter disclosed herein generally relate to a system and method for white-light illumination and near-infrared light communication using a single diode-based visible-wavelength light-source. The near-infrared beam is converted from the visible-wavelength light-source using solution-process quantum-dots for visible-light to near-infrared color conversion. The system supports communication using light, and implements optical internet-of- things through data uplink based on existing consumer electronics. DISCUSSION OF THE BACKGROUND

[0003] In the present era of the Internet of Things (loT), there is an ever- increasing demand for higher-speed, more power-efficient and secured data transmission to support various application scenarios. With the increasing number of handheld devices, the conventional radio frequency (RF) communication channel is expected to saturate in the near future. In order to resolve the bandwidth crunching issue in the RF technology, the optical wireless communication (OWC) technologies supplemented by the visible-light communication (VLC), operating in the 400-to-750- nm range of the electromagnetic spectrum, has long been envisaged to resolve these challenges. The VLC or light-fidelity (Li-Fi) technology is aimed to address the overloading issue in the RF communication channels by utilizing indoor lighting as a hub for wireless data transmission points, in which it will create a bigger channel capacity in addition to the W-Fi technology.

[0004] Although VLC is a promising technology for future indoor communications, there is a number of challenges that remain unresolved in the existing VLC or optical-loT systems. One of such challenges is that high-speed photodetectors have small areas due to resistance-capacitance (RC) limits and so they can only collect a small portion of the flux of photons, reducing the received signal power. Using a focusing element resolves this problem, but limits the field of view, making the alignment requirements stricter. Thus, to reduce the chances of blocking the optical signal, and to increase the amount of the received light, the receiver area should be of a larger size, while, at the same time, not be limited by the RC limits. These goals are contrary to a proposed design of using a flexible luminescent concentrator for free-space optical communication by utilizing optical fibers doped with visible fluorescent dyes. Similarly, in other works, fluorescent optical concentrators were aimed to increase the detection efficiency for the incoming visible-light signal, without degrading the field of view of the photodetectors. However, since these luminescent concentrators emit in the visible range, incorporating these materials into indoor optical-loT systems will create, in the long run, undesirable illumination to the human eye for an indoor environment.

[0005] Another problem of the existing VLC or optical-loT systems is the following. When implemented, the optical transmitter module may include a blue light emitter with a peak wavelength in the vicinity of 450 nm, or an ultraviolet (UV)-based light emitter with a peak emission wavelength in the vicinity of 380 nm. To cover the entire white light spectrum, the emitter is combined with multiple phosphors with a longer wavelength than the blue/UV-based light emitter in order to generate white light for general illumination and communication purposes. As a result, the generated white-light spectrum typically spans across the visible wavelength region, i.e. , 450 to 750 nm.

[0006] To support the aforementioned high-speed data transmission, phosphors with a low radiative recombination lifetime are typically required. Such a material includes halide perovskite nanocrystals, which emit in the visible range. This material is presently considered as the best choice for a high-speed intermediate phosphor for simultaneous lighting and communication purposes. However, it is noted that these phosphors are intended for integration with a light emitter for general white-light illumination and communication purposes, and the emitted light in the visible range is glaring for the human vision. However, it is desired to have non- visible light data-link in the Li-Fi technology, e.g., transmitting optical signals from an electronic apparatus (i.e., laptop, phone, tablet, etc.) back to the receiver module. [0007] Light from near-infrared (NIR) phosphors, emitting in the 750 nm to 2.5 pm region of the electromagnetic spectrum, is weakly visible or non-visible to the human vision. Given these inherent advantages of the NIR, various authors have highlighted the integration of a near-infrared vertical-cavity surface-emitting laser (VCSEL) for gesture recognition systems and light detection and ranging (LiDAR) applications [1, 2] However, the development path for VCSEL is often time- and cost-consuming due to the complex epitaxial growth and fabrication processes. [0008] In the pursuit of expanding the detection range of InGaAs-based photodetectors up to the visible range, there have been several proposed solutions based on monolithic integration of different materials [3], where GaAs and InGaAs are used for visible and NIR photodetection, respectively. Likewise, in another work [4], broadband detection was achieved by a GaSe/n-type GaSb heterostructure with the detection range of 400-1800 nm. Another solution was proposed by [5], where a broadband image sensor design was realized based on Zn2Sn04 nanowires covered by SnS quantum dots (QDs). However, it is important to note that all these devices require cumbersome fabrication process techniques, which are known to be cost and time-intensive.

[0009] Thus, there is a need for a new system that is capable of delivering white light for illumination and NIR waves for communication without using a complex manufacturing process. BRIEF SUMMARY OF THE INVENTION

[0010] According to an embodiment, there is a transmitter for illuminating with visible light and for broadcasting data with near-infrared light. The transmitter includes a single light source configured to generate an optical beam having a first wavelength in the ultraviolet to visible spectrum, a first phosphor configured to receive the optical beam and to generate a visible light beam, and a second phosphor configured to receive the optical beam and to generate a near-infrared, NIR, beam having a second wavelength, larger than the first wavelength. The first wavelength is between 400 and 750 nm and the second wavelength is between 750 nm and 2.5 pm.

[0011] According to another embodiment, there is a visible light illumination and communication system that includes a transmitter configured to generate a visible light beam and a near-infrared, NIR, beam based on a single light source, a processor configured to control the transmitter and to use the visible light beam for illumination and to use the NIR beam for data exchange, and a power source configured to supply electrical power to the transmitter and the processor. The NIR beam has a wavelength between 750 nm and 2.5 pm.

[0012] According to yet another embodiment, there is a method for illuminating with visible light and supporting data exchange with near-infrared, NIR, light. The method includes generating, with a single light source, an encoded optical beam having a first wavelength in the visible spectrum, propagating the encoded optical beam through a light guiding element, which is optically connected to the single light source, steering the encoded optical beam, with a light steering element, to a first phosphor for illuminating and/or to a second phosphor for exchanging data, generating, based on the encoded optical beam, with the first phosphor, a visible light beam having a first wavelength, and generating, based on the encoded optical beam, with the second phosphor, an encoded NIR beam having a second wavelength, larger than the first wavelength. The first wavelength is between 400 and 750 nm and the second wavelength is between 750 nm and 2.5 pm, and the encoded NIR beam preserves an encoding of the encoded optical beam.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0014] Figure 1 is a schematic diagram of an illumination and communication system that uses a NIR based transmitter;

[0015] Figures 2A to 2C illustrate a smartphone having a NIR based transmitter for data communication;

[0016] Figure 3 shows a first implementation of the NIR based transmitter;

[0017] Figure 4 shows a second implementation of the NIR based transmitter;

[0018] Figure 5 shows a third implementation of the NIR based transmitter;

[0019] Figure 6 shows a fourth implementation of the NIR based transmitter; and

[0020] Figure 7 is a flow chart of a method for using the NIR based transmitter.

DETAILED DESCRIPTION OF THE INVENTION

[0021] The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to a smartphone that uses visible-to-near-infrared color-conversion luminescent-dyes based on lead sulfide quantum dots (PbS QDs) to achieve an eye-safe high-speed optical communication link. However, the embodiments to be discussed next are not limited to a smartphone and/or to PbS QDs, but may be applied to other devices that need to wirelessly exchange data or other materials that are active in the NIR range.

[0022] Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0023] According to an embodiment, a novel smart device includes a Li-Fi transmitter with integrated solution-processed near-infrared phosphors (e.g., PbS or CdSe QDs), which is tailored for uplink optical signal relay. The solution-processed near-infrared phosphors could be spin-coated, spray-coated or applied by any other techniques known in the art for integrating red, green and blue (RGB) phosphors on a display screen of the smart device.

[0024] The near-infrared phosphors can be excited with a built-in blue-light emitter on the current handheld smart device, and thus it can readily support an uplink operation based on the near-infrared re-emission. The solution-processed PbS QDs exhibit strong absorption in the visible range, radiative recombination lifetime of 6.4 ps, as well as high photoluminescence quantum yield of up to 88%. An experimental smart phone based on an orthogonal frequency-division multiplexing (OFDM) modulation scheme established an infrared data transmission of 0.27 Mbit/s, readily supporting an indoor optical-loT system, and shed light on the possibility for PbS-integrated transceivers in supporting remote access control of multiple nodes.

[0025] The luminescent dye emitting in the NIR region, i.e. , 750 nm to 2.5 pm, which allows the absorption of any incoming signals in the visible spectrum, is non- visible and non-disturbing to the human vision, thus enabling a more conducive living environment empowered by the optical-loT systems. Apart from the receiver end for downlink operation, the NIR luminescent dye could also be integrated into an optical- loT systems for uplink operation based on visible-light sources, i.e., display screens, and thus omit the costly development path of NIR-based VCSEL arrays.

[0026] As illustrated in Figure 1, a system 100 is housed in a chamber 102, and includes plural smart devices, e.g., a smartphone 104-1, a laptop 104-2, a TV set 104-3, an AC unit 104-4, a robot 104-5, etc., each having a Li-Fi transmitter 106 and a Li-Fi receiver 108 that incorporates near-infrared dyes that can convert electromagnetic waves from the visible range, i.e., coming from a white light-emitting diode (LED), to NIR. For simplicity, only the smart phone 104-1 is shown having the Li-Fi transmitter and receiver. These dyes can be implemented on the transceiver end for both the downlink and uplink operations, allowing remote access control over a vast variety of optical-loT devices. Moreover, unlike the existing designs conceived for visible polymer-based waveguides having higher attenuation loss (i.e., 100 dB/km), the NIR emitting color-converting element of the Li-Fi transmitter and receiver can be effectively coupled into matured silica-based optical waveguides that exhibit significantly lower losses (i.e., <1 dB/km) as compared to the visible range and thus, it is further envisaged the integration of these elements into existing photonic integrated circuits (PIC).

[0027] The Li-Fi transmitter and receiver can take advantage of the silica- based optical fiber communication, operating in the NIR regime located at around 1300 nm and 1550 nm, which is a relatively matured technology and had long been efficiently used for long-distance and high-speed data transmission due to low attenuation losses. Moreover, InGaAs-based photodetectors with the detection range of 900 nm to 1700 nm are typically employed on the receiver end of the silica-based optical fiber communication for signal detection. Within the communication wavelengths of interest, the InGaAs-based photodetectors are known to have the highest responsivity and quantum efficiency as compared to other photodetectors, e.g., Si- and Ge-based photodetectors. [0028] The data 110 transmitted by the Li-Fi transmitter 106 is received by an optical receiver module 112, which can be mounted anywhere on the ceiling or walls of the chamber 102. One or more such modules may be present in the chamber. The optical receiver module 112 is connected to a control and data server 114. The system 100 further includes one or more light sources 116, which generate not only the visible light 118 for the persons present in the chamber 102, but also NIR waves 120 that transmit desired data to various smart devices present in the chamber 102. [0029] Figure 2A shows a back view of a smart phone 200, where it has a housing 202 that holds a flash light 210, a camera system 212 (which may have plural distinct cameras), the Li-Fi transmitter 106, and the Li-Fi receiver 108. Figure 2A also shows that the smart phone 200 includes a processor 220 that coordinates all the other elements of the phone. The smart phone further includes a memory 222 that stores the instructions run by the processor 220, and a power source 224, which provided electrical power to all these components. The power source 224 may be a battery. The smart phone 200 may also include a microphone 226 and a speaker 228. Figure 2B shows a front view of the phone 200, which has the Li-Fi transmitter 106 and the Li-Fi receiver 108 located on the front face instead of the back face. Figure 2B also shows a possible third implementation of the Li-Fi transmitter 106, integrated with the RGB pixels 216 within the display 214 of the smart phone. Figure 2C shows a side view of a smart phone that can be configured to have the Li-Fi transmitter 106 on the back, front, or integrated with the RGB pixels as illustrated in Figures 2A and 2B. These figures illustrate that the integration of the Li-Fi transmitter 106 within the smart phone can be achieved in various ways and there is no limitation where the transmitter can be placed. A smart device (e.g., phone, laptop, printer, microwave, washing machine, vacuum cleaner, etc.) having the Li-Fi transmitter 106 is called herein a visible light illumination and communication device. [0030] The actual structure of the Li-Fi transmitter 106 is now discussed in more detail. A few implementations of the Li-Fi transmitter 106 are possible based on the NIR QDs. Four such implementations are detailed here. However, other implementations are possible based on the present disclosure. Figure 3 illustrates a first implementation 106/300 of the Li-Fi transmitter 106. The Li-Fi transmitter 300 includes a light source 302, for example, a single laser diode, that is configured to emit, in the ultraviolet, violet or blue-wavelength region, an optical beam 304, which may be modulated to carry information, by back-end circuitry 306. The optical beam 304 has a first wavelength li in the ultraviolet-to-visible spectrum, i.e., in the range of 280 nm - 750 nm. Some modules and associated functionalities of the back-end circuitry 306 are discussed later. The modulated optical beam 304 is transmitted to and propagates through a light guiding element 308. The light guiding element 308 may include any optical waveguide, light guiding film or any similar device known in the art that could propagate a modulated optical signal. An optical waveguide may include a layer of an optical material that has a high index of refraction sandwiched between two layers having a lower index of refraction, so that the light is bound to the middle layer. The light guiding element 308 is selected so that the modulated optical beam 304 can initially propagate along a horizontal direction X and then along a vertical direction Y. This means that the light guiding element 308 can be configured to change the propagation direction of the modulated optical signal. A reflective plate 309 may be provided between the back-end circuitry 306 and the light guiding element 308 to reflect away from the back-end circuitry 306 the modulated optical beam 304.

[0031] A yellow phosphor 310 is placed on top of the light guiding element 308, so that the yellow phosphor 310 covers only a first top area 308A of the light guiding element 308. A second top area 308B of the light guiding element 308 is covered with NIR QDs 312. In this way, the modulated optical beam 304 with the first wavelength li, in the range of 280 nm - 750 nm, can be directly guided to excite the NIR QDs 312 and re-emit at a longer, second wavelength, l2, in the near-infrared region of 750 nm to 2.5 pm, as a NIR modulated beam 314, while retaining the original information of the modulated optical beam 304. Simultaneously, the optical beam 304 (modulated or not), is also directed to the yellow phosphor 310 to generate a visible light beam 316 for the flash light 210 shown in Figure 2A. This means that the yellow phosphor 310 with one or more optical element 318 form the flash light 210. Because the yellow phosphor 310 and the NIR QDs 312 are located on the same face of the light guiding element 308, this configuration would be appropriate to be placed on the back of the smart phone 200, as illustrated in Figure 2A.

[0032] In another embodiment, as shown in Figure 4, a second implementation of the Li-Fi transmitter 106 is illustrated, and this implementation 400 is also suitable for the back of the smart phone 200 as both the flash light unit 210 and the NIR QDs 312 are located on the same face of the light guiding element 308. Different from the transmitter 300, the present transmitter 400 includes a beam steering unit 410 that is located on a surface of the light guiding element 308. The modulated optical beam 304 is directed into the beam steering unit 410, which is controlled by the back-end circuitry 306. The back-end circuitry 306 then decides whether the modulated optical beam 304 is directed by the beam steering unit 410 to the NIR QDs 312 for emitting the modulated NIR beam 314, or to the yellow phosphor 310, for generating the visible light beam 316 for the flash function, or to both. Note that for ease of visualization, the NIR QDs 312 and the yellow phosphor 310 are shown detached from the beam steering unit 410. However, in a practical implementation, these elements effectively sit on the beam steering unit 410, or at least are optically connected to it.

[0033] The beam steering unit 410 may be implemented as micro-electro- mechanical systems (MEMS) micromirrors 412, digital micromirror devices (DMDs) or any apparatus known to the art for fast-switching functionalities between the flash light and the modulating NIR signal. With this configuration, the transmitter 400 may be integrated on the back panel of a smartphone for dual-functionalities of illumination and data transmission based on a single light source 302. The laser diode 302 in the transmitter 300 or 400 could be replaced by a VCSEL diode, superluminescent diode, -or light-emitting diode (LED).

[0034] In yet another implementation, the Li-Fi transmitter 106 can be configured, as shown by element 500 in Figure 5, to generate a white light 530 and the modulated NIR beam 314 by using a liquid crystal configuration. More specifically, Figure 5 shows the Li-Fi transmitter 500 including, similar to the previously discussed Li-Fi transmitters, the back-end circuits 306, the reflective plate 309, the light guiding element 308, the LD 302, and the NIR QDs 312. The transmitter 500 has, different from the previous transmitters, a liquid crystal element 510, which is sandwiched between a vertical polarizer 512, and a horizontal polarizer 514, with the vertical polarizer 512 formed in optical communication with the light guiding element 308. The liquid crystal element together with the vertical and horizontal polarizers act as an optical switch, i.e., they allow or deny the light coming from the source 302 to reach the corresponding QDs 522A to 522C and 312. A set of visible phosphors 520, e.g., a blue phosphors 522A, green 522B and red 522C, is added on top of the liquid crystal element 510 for general display and illumination applications.

[0035] For supporting the intended uplink operation for the Li-Fi transmitter 500, the near-infrared quantum dots 312 can be added on top of the liquid crystal element 510, as additional members of the pixels, as shown in the figure. This mean that the pixel 216 includes one blue phosphor 522A, one green phosphor 522B, one red phosphor 522C, and one NIR QD element 312. The blue phosphor emits a blue light 524A, the green phosphor emits a green light 524B, and the red phosphor emits a red light 524C. Thus, the pixel 216 for the Li-Fi transmitter 500 is capable to emit, in addition to the white light 530, also the modulated NIR beam 314. A beam steering module 410, e.g., MEMS micromirror, DMDs or any apparatus known to the art, can be included to dynamically control the direction of the modulated NIR optical beam 314 towards the receiver module (not shown). The liquid crystal 510, the laser diode 302, and the beam steering module 410 are electrically connected to the back-end circuitry 306 for control, switching and modulation. In the embodiment, the laser diode 302 could be replaced by a VCSEL diode, superluminescent diode, or light- emitting diode (LED).

[0036] In yet another embodiment, as shown in Figure 6, the Li-Fi transmitter 106 is implemented as element 600 (and corresponds to the transmitter 216 integrated in the display 214 in Figure 2B) and uses, instead of a single liquid crystal element 510, as shown in Figure 5, four different liquid crystal elements 610, 610A, 610B, and 610C, and corresponding vertical polarizers 612, 612A, 612B, and 612C and also corresponding horizontal polarizers 614, 614A, 614C, and 614D so that the light access to the corresponding QDs is individually controlled by the back-end circuitry 306. A separation material 616 may be provided between the various liquid crystal elements and polarizers. Thus, in this embodiment, the color of the light 530 generated by the Li-Fi transmitter 600 may be controlled and the light illumination mode and the data transmission mode may be controlled to work either simultaneously or independent of each other. A beam steering module 410 can be included to dynamically control the direction of the modulated near-infrared optical beam 314 towards the receiver module (not shown). A protective film or glass 618 may be formed over the various QDs for protection from environment.

[0037] A method for illuminating with visible light and supporting data exchange with NIR light based on the transmitter 106 is now discussed. The method includes a step 700 of generating, with a single light source, an encoded optical beam having a first wavelength in the visible spectrum, a step 702 of propagating the encoded optical beam through a light guiding element, which is optically connected to the single light source, a step 704 of steering the encoded optical beam, with a light steering element, to a first phosphor for illuminating and/or to a second phosphor for exchanging data, a step 706 of generating, based on the encoded optical beam, with the first phosphor, a visible light beam having a first wavelength, and a step 708 of generating, based on the encoded optical beam, with a second phosphor, an encoded NIR beam having a second wavelength, larger than the first wavelength. The first wavelength is between 400 and 750 nm and the second wavelength is between 750 nm and 2.5 pm, and the encoded NIR beam preserves an encoding of the encoded optical beam.

[0038] The transmitter 106 discussed above may be modified in various ways within the scope of the embodiments disclosed herein. For example, the laser diode source 302 may be selected to be capable of high-speed modulation without the limitation of conventional light sources, e.g., light-emitting diodes. The laser diode can be a Fabry-Perot laser diode or a VCSEL diode in the form of single-device. The optical beam 304 can be internally programmed to generate a continuous wave light or an optical pulse-train signals encoded with information at a selectable data rate of 1 kbit/s to 100 kbit/s, 100 kbit/s to 1 Mbit/s, 1 Mbit/s to 1 Gbit/s, 1 Gbi/s to 10 Gbit/s, and 10 Gbit/s to 100 Gbit/s. The back-end circuit 306 may be programmed for overall control, light-pathway steering or switching and signal modulation for generating the pulse-train.

[0039] The steering module 410 may be a mirror operated using a micro electromechanical system, allowing switching functionalities between exciting the yellow phosphors 310 and the near-infrared quantum dots 312 for the embodiment shown in Figure 4. In one application, the near-infrared quantum dots have a radiative recombination lifetime of from 100 fs to 1 ms. The near-infrared quantum dots may be embedded in polymer-based materials, e.g., poly(methyl methacrylate) (PMMA) and polydimethylsiloxane (PDMS). The near-infrared quantum dots are configured to absorb the first wavelength in the visible wavelength region, and then re-emitted in a second wavelength in the near-infrared wavelength region between 750 nm to 2.5 pm, which is associated to the non-visible window of the human’s vision system. In one application, the laser diode 302 could be replaced with group- ill-nitride or group-ill-arsenide based laser diodes, VCSELs or superluminescent diodes to match the peak quantum yield of the near-infrared quantum-dots emission wavelength. The laser diode may have an active area of less than 100 pm².

[0040] The laser diode 302 of the Li-Fi transmitter 106 emits the first signal having a first wavelength in the visible wavelength spectrum, the first signal being encoded with information with a high data rate of 1 kbit/s to 100 Gbit/s. The first signal can be in the form of optical pulse-train that can be steered such that it is guided to excite the second phosphor to emit near-infrared light for establishing data link non-visible to human vision. The vertical and horizontal polarizers 512 and 514, as well as the liquid crystal element 510 used in the embodiments illustrated in Figures 5 and 6 may be used to control the polarization of the first signal. The near- infrared quantum dots absorb the first signal and re-emit a second signal, having a second wavelength, in the near-infrared wavelength spectrum, while preserving the original information encoded in the first signal.

[0041] The disclosed embodiments provide a Li-Fi transmitter that is capable to be integrated in a computing device and uses a single light source for (1) visible light generation for light illumination and (2) NIR modulated signals for data exchange. It should be understood that this description is not intended to limit the invention. On the contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

[0042] Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein. [0043] This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.

References

The entire content of all the publications listed herein is incorporated by reference in this patent application.

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[3] D. M. Geum et al., “Monolithic integration of visible GaAs and near-infrared InGaAs for multicolor photodetectors by using high-throughput epitaxial lift-off toward high-resolution imaging systems,” Sci. Rep., vol. 9, no. 1, pp. 1-12, 2019.

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[5] L. Li, Z. Lou, and G. Shen, “Flexible broadband image sensors with SnS quantum dots/Zn2Sn04 nanowires hybrid nanostructures,” Adv. Funct. Mater., vol. 28, no. 6, pp. 1-10, 2018.

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Claims

WHAT IS CLAIMED IS:

1. A transmitter (106) for illuminating with visible light and for broadcasting data with near-infrared light, the transmitter (106) comprising: a single light source (302) configured to generate an optical beam (304) having a first wavelength in the ultraviolet to visible spectrum; a first phosphor (310) configured to receive the optical beam (304) and to generate a visible light beam (316); and a second phosphor (312) configured to receive the optical beam (304) and to generate a near-infrared, NIR, beam (314) having a second wavelength, larger than the first wavelength, wherein the first wavelength is between 400 and 750 nm and the second wavelength is between 750 nm and 2.5 pm.

2. The transmitter of Claim 1 , further comprising: a light guiding element (308) optically connected to the single light source (302) and configured to receive the optical beam (304) having the first wavelength; and a light steering element (410) optically connected to the light guiding element (308) and configured to direct the optical beam (304) to the first phosphor for illuminating and/or to the second phosphor for broadcasting the data.

3. The transmitter of Claim 2, wherein the light steering element includes micromirrors.

4. The transmitter of Claim 2, further comprising: back-end circuitry connected to the single light source and configured to modulate the optical beam to encode the data.

5. The transmitter of Claim 3, further comprising: a reflective plate located between the back-end circuitry and the light guiding element to reflect the optical beam.

6. The transmitter of Claim 2, further comprising: a vertical polarizer; a liquid crystal element; and a horizontal polarizer located in this order between the light guiding element and the first and second phosphors.

7. The transmitter of Claim 1 , wherein the single light source is a laser diode.

8. The transmitter of Claim 1, wherein the second phosphor includes quantum dots.

9. The transmitter of Claim 8, wherein the quantum dots include lead sulfide.

10. The transmitter of Claim 1 , wherein the first phosphor includes a red light generating phosphor, a blue light generation phosphor, and a green light generating phosphor.

11. The transmitter of Claim 10, wherein there is a lead sulfide based second phosphor for each first phosphor, and the first and second phosphors form a pixel.

12. A visible light illumination and communication system (200) comprising: a transmitter (106) configured to generate a visible light beam (316) and a near-infrared, NIR, beam (314) based on a single light source (302); a processor (220) configured to control the transmitter (106) and to use the visible light beam (316) for illumination and to use the NIR beam (314) for data exchange; and a power source (224) configured to supply electrical power to the transmitter (106) and the processor (220), wherein the NIR beam (314) has a wavelength between 750 nm and 2.5 pm.

13. The system of Claim 12, wherein the transmitter comprises: a single light source (302) configured to generate an optical beam (304) having a first wavelength in the visible spectrum; a first phosphor (310) configured to receive the optical beam (304) and to generate the visible light beam (316); and a second phosphor (312) configured to receive the optical beam (304) and to generate the NIR beam (314) having a second wavelength, larger than the first wavelength, wherein the first wavelength is between 400 and 750 nm.

14. The system of Claim 13, wherein the transmitter further comprises: a light guiding element (308) optically connected to the single light source (302) and configured to receive the optical beam (304) having the first wavelength; and a light steering element (410) optically connected to the light guiding element (308) and configured to direct the optical beam (304) either to the first phosphor for illuminating or to the second phosphor for exchanging data.

15. The system of Claim 13, wherein the single light source is a laser diode.

16. The system of Claim 13, wherein the second phosphor includes quantum dots.

17. The system of Claim 16, wherein the quantum dots include lead sulfide.

18. The system of Claim 13, wherein the first phosphor includes a red light generating phosphor, a blue light generation phosphor, and a green light generating phosphor.

19. The system of Claim 18, wherein there is a lead sulfide based second phosphor for each first phosphor, and the first and second phosphors form a pixel of a screen.

20. A method for illuminating with visible light and supporting data exchange with near-infrared, NIR, light, the method comprising: generating (700), with a single light source (302), an encoded optical beam (304) having a first wavelength in the visible spectrum; propagating (702) the encoded optical beam (304) through a light guiding element (308), which is optically connected to the single light source (302); steering (704) the encoded optical beam (304), with a light steering element (410), to a first phosphor for illuminating and/or to a second phosphor for exchanging data; generating (706), based on the encoded optical beam (304), with the first phosphor (310), a visible light beam (316) having a first wavelength; and generating (708), based on the encoded optical beam (304), with the second phosphor (312), an encoded NIR beam (314) having a second wavelength, larger than the first wavelength, wherein the first wavelength is between 400 and 750 nm and the second wavelength is between 750 nm and 2.5 pm, and wherein the encoded NIR beam preserves an encoding of the encoded optical beam.