Integrated design method of two-dimensional beam scanning and lighting source for LiFi communication system for mobile targets

Abstract

The present invention relates to the field of optical communications technology and provides a method for integrating two-dimensional beam scanning and illumination light sources in a LiFi communication system for mobile targets. The method comprises the following steps: S1 generating initial information; S2 performing digital signal processing; S3 performing digital-to-analog conversion; S4 converting electrical signals into infrared light signals; S5 amplifying the signals with an amplifier and outputting them from an optical fiber; S6 transmitting the signals to an AWGR; S7 optical fiber connecting the AWGR to a two-dimensional optical fiber array; S8 selecting, driving, and modulating LEDs; S9 interweaving the LEDs and ferrules in the two-dimensional optical fiber array; S10 energy management; S11 providing a lens to increase the image spot size; S12 transmitting optical signals to corresponding receivers; S13 focusing and coupling; S14 amplifying the signals with an amplifier; S15 performing photoelectric conversion and amplification via a PIN-TIA; S16 performing analog-to-digital conversion of the signals; and S17 restoring the initial information. The present invention can provide high-capacity and high-precision wavelength control.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a method for integrating two-dimensional beam scanning and illumination light sources in a LiFi communication system for mobile targets. Background Art

[0002] In the future, areas such as daily life and production will require support from communications infrastructure. Such infrastructure requires not only a robust and versatile wired network as the backbone of the infrastructure, but also wireless communication links to connect to actual devices. These wireless links need to have high speed, high reliability, and low latency. To date, radio frequency signals have been the most commonly used in wireless communications. However, as communication speed requirements increase and the spatial density of connections increases, the latency requirements for device-to-device interactions are becoming increasingly stringent, and radio frequency spectrum resources are becoming increasingly scarce, which is more likely to lead to communication congestion. Wireless optical communication (OWC) technology effectively meets the needs of people's future daily life and production and is widely considered to be one of the potential key technologies for future communications.

[0003] To avoid capacity sharing between devices and thus avoid congestion, relatively narrow beams can be used. Narrow beams have a smaller divergence angle, allowing each beam to serve only a single user device. By only delivering optical signals to the corresponding receiver when needed, this solution can save power and provide better privacy protection. Furthermore, considering factors such as high energy efficiency and safety, the infrared band is considered the most suitable band for beam scanning. By using an infrared beam with a wavelength of 1500nm, eye safety standards allow transmission powers of up to 10dBm, which is at least 15dBm higher than the permitted power for visible light beams. Furthermore, the light intensity delivered to a single user device by a confined, narrow infrared beam is higher than that of a more divergent VLC beam. Therefore, narrow infrared optical communication can offer a significantly higher link power budget than visible light communication, enabling higher data rates.

[0004] Furthermore, the mature fiber-optic communications market offers a wide range of optical device options for infrared light beam scanning, operating in the S+L+C band (1460-1625nm, equivalent to a 20.9 THZ bandwidth). Currently, widely used beam scanning systems include systems with actively controlled beam steering elements (active elements) and systems such as diffraction elements (passive elements). Active element systems include micro-electromechanical systems (MEMS) or spatial light modulators (SLM-S). Each beam can carry 10 Gbit / s or more, but requires a separate steering element. The need to carefully maintain the relationship between data and control signals limits the system's ability to expand to more beams and complicates system management and control. Diffraction elements can change the direction of the beam by varying the wavelength of the data signal. The beam's steering is implicitly controlled by the wavelength, which also carries the data signal. Therefore, the wavelength acts as an embedded control channel, simplifying system management and control. Common diffraction elements include a pair of reflective or transmissive gratings, a glass body containing numerous Bragg grating structures, and other devices for two-dimensional steering.

[0005] While active electronically controlled devices offer high scanning accuracy and dynamic control, they are complex to manufacture and consume more power. Compared to passive devices, active devices require longer response times, resulting in excessive latency. Traditional passive devices also have limited scanning angles and require improved accuracy. Summary of the Invention

[0006] The present invention provides a method for integrating two-dimensional beam scanning and illumination light source design of a LiFi communication system for mobile targets, which can provide high-capacity and high-precision wavelength control.

[0007] According to the present invention, a method for integrating two-dimensional beam scanning and lighting source design of a LiFi communication system for mobile targets includes the following steps:

[0008] S1 generates the initial data information flow;

[0009] S2 performs digital signal processing (DSP) on the data information;

[0010] S3 converts the digital signal processed data into an electrical signal through a digital-to-analog converter (DAC).

[0011] S4 feeds the electrical signal to a single-driver Mach-Zehnder modulator. The analog electrical signal output and the optical signal generated by the laser LD serve as the input of the modulator, modulating the digitally processed signal into an infrared optical signal.

[0012] S5 uses erbium-doped fiber amplifier (EDFA) to amplify infrared light signals, and the signals are output through single-mode optical fiber;

[0013] S6 transmits the infrared signal to the arrayed waveguide grating router AWGR through a single-mode optical fiber;

[0014] The S7AWGR is connected to the two-dimensional fiber array end-to-end using single-mode optical fibers, and the infrared light signal is emitted from the fiber ferrule on the fiber array for spatial optical transmission.

[0015] S8 selects, drives and modulates the light-emitting diode (LED) according to the transmission distance;

[0016] The S9 interweaves LEDs and single-mode fiber ferrules into a two-dimensional fiber array, synchronously controlling LED illumination and beam scanning.

[0017] S10 performs energy management on LED light sources;

[0018] S11 sets a lens coaxial with the fiber array in the optical path to increase the image spot size and realize wavelength-tuned two-dimensional beam scanning;

[0019] The S12 optical signal is transmitted through free space to the receiver at the corresponding position;

[0020] The S13 optical signal is collected by the collimator at the receiving end and coupled into the single-mode optical fiber;

[0021] S14 uses a linear semiconductor optical amplifier to amplify the received signal and increase the received power;

[0022] S15 uses a diode-transimpedance amplifier PIN-TIA to perform photoelectric conversion on the amplified optical signal and further amplify the converted electrical signal;

[0023] S16 uses an analog-to-digital converter (ADC) to convert the electrical signal into digital form and collect the converted digital signal;

[0024] S17 performs digital signal processing on the collected digital signal to restore the original information.

[0025] Preferably, in S4, a modulator is used to carry the signal in the infrared band with a wavelength of λ.

[0026] Preferably, in S6, the AWGR has multiple output ports, and infrared light signals of different bands are output from different ports.

[0027] Preferably, in S7, the mode field radius of the single-mode optical fiber is w0, and the applicable wavelength is λ, so the light wave divergence angle α is described as:

[0028]

[0029] One end of the single-mode optical fiber is connected to the AWGR using FC or APC, and the other end is connected to the optical fiber array using a ferrule. The optical fiber array is honeycomb-shaped, and the fiber gap between adjacent optical fibers is Δy.

[0030] Preferably, in S7, the LEDs and the optical fiber ferrules are arranged in an interlaced manner in a two-dimensional array to ensure uniform illumination and scanning of the image plane.

[0031] Preferably, in S8, the LED power is adjusted by the driving circuit so that the LED output light intensity matches the ambient light intensity to ensure uniform illumination in the communication environment; the LED can be modulated into a communication signal to enhance the visible light communication (VLC) function; and the radius r of the LED spot should satisfy:

[0032] 2r≥L

[0033] Where L is the width of the receiving end image plane. For the illumination divergence angle β, it must satisfy:

[0034]

[0035] Where b0 is the distance from the transmitter to the receiver.

[0036] Preferably, in S9, the LED and the AWGR can be arranged in a variety of spatial topologies, and the LED's illumination light and the AWGR's infrared beam scanning can be coordinated through a synchronous control circuit.

[0037] Preferably, in S10, during the lighting process, the LED is monitored and adjusted in real time through the intelligent energy management system, that is, the working state of the LED is automatically optimized according to the ambient light conditions and application requirements; the working mode of the LED is dynamically adjusted according to the communication load and lighting requirements.

[0038] Preferably, in S10, the lens uses a defocusing method to further reduce the required hardware and space size, that is, to reduce the distance v from the two-dimensional optical fiber array to the lens. The relative defocus parameter p is described as:

[0039] p=1-v / f

[0040] Here, the focal length of the lens, f, is described as:

[0041]

[0042] Where M is the number of ports on the diagonal of the fiber array. To ensure that the light spot at the receiving end at distance b0 from the lens is covered without gaps, that is, the light spot is external, the fiber gaps on the fiber array should meet the following requirements:

[0043]

[0044] In addition, to ensure that the light waves of each port pass through the lens perfectly, the diameter of the front lens group is Dlens Should meet the following requirements:

[0045] Dlens≥(M-1)|Δy|+2f(1-p)tanα.

[0046] As a preference, in S10, signals from transmitters of different wavelength bands are received by receivers at different positions; the diameter D of the lens of the front lens group of the collimator at the receiving end is lens Need to meet:

[0047] D lens =2tanα{f+p(bf)}

[0048] Where b is the distance between the transmitting and receiving lenses.

[0049] The beneficial effects of the present invention are as follows:

[0050] 1. High-precision beam scanning. It can accurately transmit each wavelength signal to the corresponding receiver.

[0051] 2. Fast response time. It can quickly scan the required receiving end location and transmit information.

[0052] 3. Precise wavelength control: Different wavelength signals are output through different ports, making the control of signal wavelength very precise.

[0053] 4. Simple system management and control. No separate steering components are required, and the relationship between data signals and control signals is simple to maintain.

[0054] Compared to other passive component systems, this invention achieves higher-precision scanning through more precise wavelength control, significantly increasing user capacity. Furthermore, as a passive component, the AWGR does not introduce significant latency, making it more capable of targeting moving targets. Furthermore, this invention integrates the AWGR scanning system with the illumination source, overcoming the limitation of narrow-beam systems in providing illumination. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Flowchart of a method for integrating two-dimensional beam scanning and lighting source design of a LiFi communication system for a mobile target in an embodiment;

[0056] Figure 2 An experimental diagram of a method for integrating two-dimensional beam scanning and illumination light source design for a LiFi communication system for a mobile target in an embodiment;

[0057] FIG3( a ) is a design diagram of a two-dimensional optical fiber array with an interwoven spatial topology of LEDs and AWGRs according to an embodiment;

[0058] FIG3( b ) is a two-dimensional optical fiber array design diagram showing a spatial topology scheme in which LEDs and AWGRs are arranged in an equilateral triangle with the center of the optical fiber array in an embodiment;

[0059] Figure 4 Schematic diagram of the defocusing method in the embodiment. DETAILED DESCRIPTION

[0060] In order to further understand the content of the present invention, the present invention is described in detail with reference to the accompanying drawings and embodiments. It should be understood that the embodiments are merely for explaining the present invention and are not intended to limit the present invention.

[0061] Example

[0062] like Figure 1 and Figure 2 As shown, this embodiment provides a method for integrating two-dimensional beam scanning and lighting source design of a LiFi communication system for mobile targets, which includes the following steps:

[0063] S1 generates the initial data information flow;

[0064] S2 performs digital signal processing (DSP) on the data information;

[0065] S3 converts the digital signal processed data into an electrical signal through a digital-to-analog converter (DAC).

[0066] S4 feeds the electrical signal to a single-driver Mach-Zehnder modulator. The analog electrical signal output and the optical signal generated by the laser LD serve as the input of the modulator, modulating the digitally processed signal into an infrared optical signal.

[0067] S5 uses erbium-doped fiber amplifier (EDFA) to amplify infrared light signals, and the signals are output through single-mode optical fiber;

[0068] S6 transmits the infrared signal to the arrayed waveguide grating router AWGR through a single-mode optical fiber;

[0069] The S7 AWGR is connected end-to-end to a two-dimensional fiber array using single-mode optical fibers, and the infrared light signal is emitted from the fiber ferrule on the fiber array for spatial optical transmission.

[0070] S8 selects, drives and modulates the light-emitting diode (LED) according to the transmission distance;

[0071] The S9 interweaves LEDs and single-mode fiber ferrules into a two-dimensional fiber array, synchronously controlling LED illumination and beam scanning.

[0072] S10 performs energy management on LED light sources;

[0073] S11 sets a lens coaxial with the fiber array in the optical path to increase the image spot size and realize wavelength-tuned two-dimensional beam scanning;

[0074] The S12 optical signal is transmitted through free space to the receiver at the corresponding position;

[0075] The S13 optical signal is collected by the collimator at the receiving end and coupled into the single-mode optical fiber;

[0076] S14 uses a linear semiconductor optical amplifier to amplify the received signal and increase the received power;

[0077] S15 uses a diode-transimpedance amplifier PIN-TIA to perform photoelectric conversion on the amplified optical signal and further amplify the converted electrical signal;

[0078] S16 uses an analog-to-digital converter (ADC) to convert the electrical signal into digital form and collect the converted digital signal;

[0079] S17 performs digital signal processing on the collected digital signal to restore the original information.

[0080] In S4, a modulator is used to carry the signal in the infrared band with a wavelength of λ.

[0081] In S6, the AWGR has multiple output ports, and infrared light signals of different wavelengths are output from different ports. In this embodiment, a 96-port AWGR can be selected to output 96 infrared lights in the 1500nm to 1600nm wavelength band.

[0082] In S7, the mode field radius of the single-mode fiber is w0, and the applicable wavelength is λ, so the light wave divergence angle α is described as:

[0083]

[0084] One end of the single-mode optical fiber is connected to the AWGR using FC or APC, and the other end is connected to the optical fiber array using a ferrule. The optical fiber array is honeycomb-shaped, making the array more compact, and the optical fiber gap between adjacent optical fibers is Δy.

[0085] In S7, LEDs and fiber optic ferrules are arranged in a two-dimensional array using an interlaced method to ensure uniform illumination and scanning of the image plane.

[0086] In this embodiment, each AWGR port corresponds to each port of the fiber array, and both are connected using single-mode fiber. One end of the fiber connects to the AWGR using FC / APC, while the other end connects to the fiber array using a ferrule. The fiber array is designed in a honeycomb pattern for a more compact array. To minimize lens size, the fiber gap is 1.4 mm, and the mode field diameter of the single-mode fiber is 10.5 μm.

[0087] In S8, the LED power is adjusted by the driving circuit to match the LED output light intensity with the ambient light intensity, ensuring uniform illumination in the communication environment. The LED can be modulated into a communication signal to enhance the visible light communication (VLC) function. The radius r of the LED spot should satisfy the following conditions:

[0088] 2r≥L

[0089] Where L is the width of the receiving end image plane. For the illumination divergence angle β, it must satisfy:

[0090]

[0091] Where b0 is the distance from the transmitter to the receiver.

[0092] In S9, the LEDs and AWGR can be arranged in a variety of spatial topologies, such as an interwoven arrangement of LEDs and optical fibers, as shown in Figure 3(a), or an equilateral triangle arrangement of LEDs centered around the optical fiber array, as shown in Figure 3(b). A synchronous control circuit coordinates the LED illumination and the AWGR's infrared beam scanning. This step ensures that the optical signal is transmitted without affecting the uniformity and brightness of the spatial illumination.

[0093] In S10, during the lighting process, the intelligent energy management system monitors and adjusts the LED in real time. That is, according to the ambient light conditions and application requirements (brightness, color temperature), the working state of the LED is automatically optimized to achieve higher functionality and lower energy consumption. According to the different communication loads and lighting requirements, the working mode of the LED is dynamically adjusted to reduce unnecessary energy waste.

[0094] In order to further reduce aberrations (especially field curvature), a commercial lens with a focal length of f / 50mm and an aperture of f / 0.95 was selected for the S10. The diameter of the rear lens group is only 24mm, which meets the requirements of the S7 for the light emitted from the fiber array to pass through the lens perfectly. Figure 4 As shown in Figure 1, the lens uses a defocusing method to further reduce the required hardware and space size, that is, to reduce the distance v from the two-dimensional fiber array to the lens. The relative defocus parameter p is described as:

[0095] p=1-v / f

[0096] Here, the focal length of the lens, f, is described as:

[0097]

[0098] Where M is the number of ports on the diagonal of the fiber array. To ensure that the light spot at the receiving end at distance b0 is covered without gaps, that is, the light spot is external, the fiber gaps on the fiber array should meet the following requirements:

[0099]

[0100] In addition, to ensure that the light waves of each port pass through the lens perfectly, the diameter of the front lens group is D lens Should meet the following requirements:

[0101] Dlens≥(M-1)|Δy|+2f(1-p)tanα.

[0102] In S10, signals from transmitters of different bands are received by receivers at different positions; the diameter of the lens of the collimator in front of the receiver is D lens Need to meet:

[0103] D lens =2tanα{f+p(bf)}

[0104] Where b is the distance between the transmitting and receiving lenses.

[0105] This embodiment achieves higher-precision scanning through precise wavelength control and significantly increases user capacity. Furthermore, as a passive component, the AWGR does not introduce significant latency, making it more capable of targeting moving targets. Furthermore, this embodiment integrates the AWGR scanning system with the illumination source, addressing the limitation of narrow-beam systems in providing illumination.

[0106] The above is a schematic description of the present invention and its embodiments, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs a structure and embodiment similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A design method for integrating two-dimensional beam scanning and lighting sources in a LiFi communication system for mobile targets, characterized by: The following steps are involved: S1 generates the initial data information flow; S2 performs digital signal processing (DSP) on the data information; S3 converts the digital signal processed data into an electrical signal through a digital-to-analog converter (DAC). S4 feeds the electrical signal to a single-driver Mach-Zehnder modulator. The analog electrical signal output and the optical signal generated by the laser LD serve as the input of the modulator, modulating the digitally processed signal into an infrared optical signal. S5 uses erbium-doped fiber amplifier (EDFA) to amplify infrared light signals, and the signals are output through single-mode optical fiber; S6 transmits the infrared signal to the arrayed waveguide grating router AWGR through a single-mode optical fiber; The S7 AWGR is connected end-to-end to a two-dimensional fiber array using single-mode optical fibers, and the infrared light signal is emitted from the fiber ferrule on the fiber array for spatial optical transmission. S8 selects, drives and modulates the light-emitting diode (LED) according to the transmission distance; The S9 interweaves LEDs and single-mode fiber ferrules into a two-dimensional fiber array, synchronously controlling LED illumination and beam scanning. S10 performs energy management on LED light sources; S11 sets a lens coaxial with the fiber array in the optical path to increase the image spot size and realize wavelength-tuned two-dimensional beam scanning; The S12 optical signal is transmitted through free space to the receiver at the corresponding position; The S13 optical signal is collected by the collimator at the receiving end and coupled into the single-mode optical fiber; S14 uses a linear semiconductor optical amplifier to amplify the received signal and increase the received power; S15 uses a diode-transimpedance amplifier PIN-TIA to perform photoelectric conversion on the amplified optical signal and further amplify the converted electrical signal; S16 uses an analog-to-digital converter (ADC) to convert the electrical signal into digital form and collect the converted digital signal; S17 performs digital signal processing on the collected digital signal to restore the original information.

2. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 1, characterized in that: In S4, a modulator is used to carry the signal in the infrared band with a wavelength of λ.

3. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 2, characterized in that: In S6, AWGR has multiple output ports, and infrared light signals of different bands are output from different ports.

4. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 3 is characterized in that: In S7, the mode field radius of the single-mode fiber is w0, and the applicable wavelength is λ, so the light wave divergence angle α is described as: One end of the single-mode optical fiber is connected to the AWGR using FC or APC, and the other end is connected to the optical fiber array using a ferrule. The optical fiber array is honeycomb-shaped, and the fiber gap between adjacent optical fibers is Δy.

5. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 4, characterized in that: In S7, LEDs and fiber optic ferrules are arranged in a two-dimensional array using an interlaced method to ensure uniform illumination and scanning of the image plane.

6. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 5, characterized in that: In S8, the LED power is adjusted by the driving circuit to match the LED output light intensity with the ambient light intensity, ensuring uniform illumination in the communication environment. The LED can be modulated into a communication signal to enhance the visible light communication (VLC) function. The radius r of the LED spot should satisfy the following conditions: 2r≥L Where L is the width of the receiving end image plane. For the illumination divergence angle β, it must satisfy: Where b0 is the distance from the transmitter to the receiver.

7. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 6, characterized in that: In S9, LED and AWGR can be used in a variety of spatial topologies, and the LED lighting and AWGR infrared beam scanning are coordinated through the synchronous control circuit.

8. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 7, characterized in that: In S10, during the lighting process, the intelligent energy management system monitors and adjusts the LED in real time, that is, automatically optimizes the working state of the LED according to the ambient light conditions and application requirements; and dynamically adjusts the working mode of the LED according to the communication load and lighting requirements.

9. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 8, characterized in that: In S10, the lens uses a defocusing method to further reduce the required hardware and space size. That is, the distance v from the two-dimensional fiber array to the lens is reduced. The relative defocus parameter p is described as: p=1-v / f Here, the focal length of the lens, f, is described as: Where M is the number of ports on the diagonal of the fiber array. To ensure that the light spot at the receiving end at distance b0 from the lens is covered without gaps, that is, the light spot is external, the fiber gaps on the fiber array should meet the following requirements: In addition, to ensure that the light waves of each port pass through the lens perfectly, the diameter of the front lens group is D lens Should meet the following requirements: Dlens≥(M-1)|Δy|+2f(1-p)tanα.

10. The method for designing an integrated two-dimensional beam scanning and lighting source for a mobile target LiFi communication system according to claim 9, characterized in that: In S10, signals from transmitters of different bands are received by receivers at different positions; the diameter of the lens of the collimator in front of the receiver is D lens Need to meet: D lens =2tanα{f+p(b-f)} Where b is the distance between the transmitting and receiving lenses.

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