Single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device

Abstract

Single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication devices belong to the field of wireless optical communication technology. Existing technologies fail to take into account both communication quality and communication distance under the premise of coaxial transceiver. The present invention is characterized in that a triple-clad optical fiber is arranged on the optical path between the optical antenna and the laser diode and photodiode; the triple-clad optical fiber is composed of a core, an inner cladding, a middle cladding and an outer cladding from the inside to the outside, and the middle cladding is doped with a laser working material and can generate laser light with the same wavelength as the communication light; at one end of the triple-clad optical fiber, the center is the core incident end face a, and the other two end faces are the inner cladding output end face b' and the middle cladding incident end face c, each made by the tapering technology; the end face of the other end of the triple-clad optical fiber is located at the back focus of the optical antenna; the laser diode light outlet and the core incident end face a are connected by a single-mode optical fiber; the inner cladding output end face b' and the photodiode light inlet are connected by a multi-mode optical fiber.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless optical communications. Background Art

[0002] Wireless optical communication technology uses light as its signal carrier. The optical carrier frequency is 4 to 5 orders of magnitude higher than microwave frequencies, enabling single-channel transmission rates exceeding 10 Gb / s. This makes it an optimal solution for kilometer-scale information transmission. Existing wireless optical communication devices require separate optical systems for transmitting and receiving optical signals. These two optical systems inevitably result in a larger and heavier device. Furthermore, the need to maintain parallel optical axes makes assembly and alignment challenging, making them unsuitable for simple, portable applications. Consequently, coaxial transceiver wireless optical communication technology has emerged. For example, a Chinese invention patent, patent number ZL201810343439.2, entitled "A Long-Distance Wireless Laser Wi-Fi Communication System and Method," proposes a solution that utilizes either single-mode or multimode optical fiber connected to an optical antenna. A wavelength division multiplexer (WDM) divides the wavelengths to achieve coaxial transmission and reception of optical signals, addressing the challenges of previous technologies. However, single-mode fiber and multimode fiber each have their own technical advantages. For example, when transmitting optical signals, single-mode fiber can ensure higher beam quality, which is beneficial for the receiving end; when receiving optical signals, multimode fiber can ensure that more optical energy is received (the amount of optical energy that can be received is proportional to the square of the fiber core diameter), resulting in a stronger received optical signal. However, the wireless optical communication devices on both sides of the communication are identical, using either single-mode fiber or multimode fiber. Therefore, it is impossible to simultaneously meet the different needs of both communicating parties. In particular, if single-mode fiber is used to achieve higher beam quality, the communication distance will inevitably be shortened. Summary of the Invention

[0003] To balance communication quality and distance while maintaining coaxial transmission and reception, we have proposed a technical solution called "single-mode and multi-mode coaxial transmission and reception kilometer-level wireless optical communication device," which can achieve high-speed, high-quality wireless transmission of data over a kilometer-level distance.

[0004] In the single-mode multi-mode coaxial transceiver kilometer-level wireless optical communication device of the present invention, Figure 1As shown, on the one hand, the communication end of the physical layer interface is electrically connected to the driver and the laser diode in sequence; on the other hand, the photodiode, the transimpedance amplifier, the limiting amplifier, and the communication end of the physical layer interface are electrically connected in sequence; the optical antenna 1 is arranged on the output light path of the laser diode and the incident light path of the photodiode; it is characterized in that a triple-clad optical fiber is arranged on the light path between the optical antenna 1 and the laser diode and the photodiode; the pump main control module, the pump driver, and the pump laser diode are electrically connected in sequence, the pump main control module is also electrically connected to the temperature control component, and the pump laser diode housing is in physical contact with the temperature control component; the monitoring photodiode is electrically connected to the pump main control module; as shown Figure 2 The triple-clad optical fiber is composed of a core 2, an inner cladding 3, a middle cladding 4 and an outer cladding 5 from the inside out, and the refractive index is 、 、 、 ,and > > > , the middle cladding 4 is doped with laser working material, which can generate laser light with the same wavelength as the communication light; at one end of the triple-clad optical fiber, the center is the core incident end face a, and the other two end faces are the inner cladding output end face b' and the middle cladding incident end face c, which are made of the inner cladding and the middle cladding respectively by the taper technology; the end face of the other end of the triple-clad optical fiber is located at the back focus of the optical antenna 1, and on this end face, the core output end face a' is located at the center of the annular inner cladding incident end face b; the splitting channel 6 of the core 2 passes through the inner cladding 3, the middle cladding 4 and the outer cladding 5 in sequence, one end of the splitting channel 6 is led out from the core 2, and the other end forms the monitoring light output end face a" on the surface of the outer cladding 5; a pump light overflow channel 7 is opened from the contact surface between the middle cladding 4 and the outer cladding 5 to the outer surface of the outer cladding 5; Figure 1 、 Figure 2 As shown, a single-mode optical fiber is used to conduct electricity between the laser diode light outlet and the core incident end face a, and the core diameter of the single-mode optical fiber is the same as the core diameter of the core 2; a multi-mode optical fiber is used to conduct electricity between the inner cladding output end face b' and the light inlet of the photodiode, and the core diameter of the multi-mode optical fiber is the same as the diameter of the inner cladding output end face b'; an optical fiber is used to conduct electricity between the pump laser diode and the middle cladding incident end face c, and the core diameter of the optical fiber is the same as the diameter of the middle cladding incident end face c; an optical fiber is used to conduct electricity between the monitoring light output end face a" and the light inlet of the monitoring photodiode, and the core diameter of the optical fiber is the same as the diameter of the monitoring light output end face a".

[0005] The technical effects of the present invention are as follows: Figure 1 、 Figure 2 shown.

[0006] The data end of the physical layer interface is electrically connected to the user equipment. The communication data is converted into a data format by the physical layer interface to obtain a communication data electrical signal. The driver drives the laser diode to emit an intensity-modulated communication data optical signal. The communication data optical signal enters the core 2 of the triple-clad optical fiber through the single-mode optical fiber, is enhanced, and is emitted from the core output end face a', transmitted in free space through the optical antenna 1, and sent to the other user.

[0007] Both communicating parties use the same wireless optical communication device.

[0008] The reception of the communication data optical signal is still completed by the optical antenna 1. It enters the inner cladding 3 of the triple-clad optical fiber from the inner cladding incident end face b, and after being enhanced, it is emitted from the inner cladding output end face b' and guided to the photodiode by the multimode optical fiber. The communication data optical signal is converted into a communication data electrical signal, first amplified by a transimpedance amplifier, then adjusted in amplitude by a limiting amplifier, and finally reversed in data format by the physical layer interface and sent to the user equipment.

[0009] During the wireless optical communication process, the pump master control module instructs the pump driver to output a constant current, driving the pump laser diode to generate pump light. The pump light is guided by the optical fiber to the triple-clad optical fiber, entering the middle cladding 3 from the middle cladding incident end face c, exciting the laser working material therein and generating enhanced light with the same wavelength as the communication light. This enhanced light is transmitted simultaneously in the middle cladding 3 and the fiber core 2, providing additional energy and enhancing the transmitted and received communication data optical signals.

[0010] During the aforementioned process of amplifying the communication data optical signal, the pump laser diode housing is in physical contact with the temperature control assembly. Therefore, the temperature control assembly, in conjunction with the pump main control module, controls the operating temperature of the pump laser diode. In a specific embodiment of the present invention, the temperature control assembly comprises a heat sink, a thermistor, and a semiconductor cooler. The pump laser diode and the thermistor are mounted on the heat sink in close proximity, and the semiconductor cooler is bonded to the heat sink. The pump main control module controls the operating state (heating or cooling) of the semiconductor cooler based on the pump laser diode temperature, which is collected and fed back by the thermistor, to stabilize the pump laser diode temperature at the desired value. Because the fiber core 2 is provided with a light splitting channel 6, a small amount of communication data optical signal within the fiber core 2 is emitted as monitoring light from the monitoring light exit end face a". This light is then guided by the optical fiber to the monitoring photodiode, which converts the signal into a monitoring electrical signal and transmits it to the pump main control module. The pump main control module then controls the pump driver based on this monitoring electrical signal, regulating the pump driver's output current, thereby stabilizing the intensity of the transmitted communication data optical signal at the desired value. Because the outer cladding 5 has a pump light overflow channel 7, useless pump light escapes through this channel, thereby purifying the communication data optical signal transmission channel.

[0011] It can be seen that compared with the prior art, the present invention has the following advantages:

[0012] The present invention balances communication quality and distance while maintaining coaxial transmission and reception. In the kilometer-level wireless optical communication device for single-mode and multimode coaxial transmission and reception, the transmitting and receiving optical communication data signals utilize the same triple-clad optical fiber and the same optical antenna 1, achieving coaxial transmission and reception. Furthermore, the transmitting optical communication data signal is transmitted from the laser diode to the triple-clad optical fiber using a single-mode optical fiber, ensuring the quality of the transmitted optical communication data signal. The receiving optical communication data signal is transmitted from the triple-clad optical fiber to the photodiode using a multimode optical fiber, ensuring the strength of the received optical communication data signal.

[0013] The triple-clad optical fiber in the present invention's single-mode and multi-mode coaxial transceiver kilometer-scale wireless optical communication device serves as an optical component, one of its functions being to enable optical transmission between the optical antenna 1 and the laser diode and photodiode. More importantly, it utilizes pump light to generate energy gain, achieving optical signal amplification, significantly increasing the energy redundancy of the communication link and enabling high-speed, high-quality wireless transmission of communication data optical signals over kilometer-scale distances. Furthermore, the high energy redundancy of the communication link minimizes environmental impacts on wireless optical communication, ensuring strong environmental adaptability and ensuring normal wireless optical communication in various environments. The triple-clad optical fiber's inner cladding 3 receives the communication data optical signal. Compared to the core 2, this layer has a larger cross-sectional area, receiving more optical energy under the same conditions and achieving higher energy efficiency. This further increases the energy redundancy of the communication link and further mitigates environmental influences.

[0014] The coaxial transceiver structure can effectively reduce the volume and weight of the wireless optical communication device, making it easy to carry. It has low requirements for the processing accuracy of each component and does not require multiple optical axes to be parallel. The end face of the other end of the triple-clad optical fiber can be located at the back focus of the optical antenna 1. The device is simple and easy to assemble and adjust, and the cost is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic block diagram of the overall structure and working conditions of the present invention, which also serves as an abstract drawing. Figure 2 Schematic diagram of the triple-clad optical fiber structure and working conditions in the present invention. DETAILED DESCRIPTION

[0016] The contents that need to be further limited to the single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device of the present invention include:

[0017] The physical layer interface is an Ethernet physical layer interface module, which is connected to the user equipment through a network cable.

[0018] The driver is a constant current drive circuit.

[0019] The output wavelength of the laser diode is 1550nm and the optical power is 5mW.

[0020] The photodiode is an indium gallium arsenide photodiode.

[0021] Optical antenna 1 is a beam-shaping lens group consisting of five spherical lenses, which realizes the collimated output of the transmitted communication data optical signal and the converged input (SISO) of the received communication data optical signal. It has an aperture of 86mm and an effective light aperture of 80mm. Each lens is coated with a broadband anti-reflection and anti-reflection coating in the 1550nm working band to reflect stray light and increase the transmission of communication light.

[0022] The optical fiber connecting the monitoring light emitting end face a" and the monitoring photodiode adopts a single-mode optical fiber.

[0023] An isolator is installed on the single-mode optical fiber path between the laser diode and the triple-clad optical fiber, and between the triple-clad optical fiber and the monitoring photodiode to prevent reflections from the device and solder joints, reduce the noise index of the triple-clad optical fiber, and increase stability.

[0024] The optical fiber between the conduction pump laser diode and the incident end face c of the middle cladding adopts a multimode optical fiber, which can transmit sufficient light energy to adapt to kilometer-level wireless optical communication.

[0025] The pump laser diode is a distributed feedback laser diode with a built-in Bragg grating, side emission, an output wavelength of 980nm, and an optical power of 600mW.

[0026] The temperature control component consists of a heat sink, a thermistor, and a semiconductor cooler. The pump main control module is electrically connected to the thermistor and semiconductor cooler in the temperature control component. The pump laser diode and the thermistor are close to each other and are both installed on the heat sink. The semiconductor cooler is fitted to the heat sink.

[0027] The core 2, inner cladding 3, and middle cladding 4 of the triple-cladding optical fiber are all made of quartz glass. The laser working substance doped in the middle cladding 4 is erbium with a lasing wavelength of 1550nm. The outer cladding 5 is a polymer coating. The refractive indices of the core 2, inner cladding 3, middle cladding 4, and outer cladding 5 are 、 、 、 ,and > > > The technical effect is that, on the one hand, it prevents the signal light from escaping from the core 2 and the inner cladding 3 to the outer layer, and on the other hand, it ensures that the enhanced light generated by the middle cladding 4 can be incident on the inner cladding 3 and the core 2 to enhance the signal light.

Claims

1. A single-mode or multi-mode coaxial transceiver kilometer-level wireless optical communication device, wherein the communication end of the physical layer interface is electrically connected to the driver and the laser diode in sequence; the photodiode, the transimpedance amplifier, the limiting amplifier, and the communication end of the physical layer interface are electrically connected in sequence; the optical antenna (1) is arranged on the output light path of the laser diode and the incident light path of the photodiode; and the device is characterized in that: A triple-clad optical fiber is provided on the optical path between the optical antenna (1) and the laser diode and the photodiode; a pump main control module, a pump driver, and a pump laser diode are electrically connected in sequence, the pump main control module is also electrically connected to a temperature control component, and the pump laser diode housing is in physical contact with the temperature control component; the monitoring photodiode is electrically connected to the pump main control module; the triple-clad optical fiber is composed of a core (2), an inner cladding (3), a middle cladding (4), and an outer cladding (5) from the inside out, and the refractive index is 、 、 、 ,and > > > The middle cladding (4) is doped with a laser working material and can generate a laser with the same wavelength as the communication light; at one end of the triple-cladding optical fiber, the center is the core incident end face a, and the other two end faces are the inner cladding output end face b' and the middle cladding incident end face c, which are made by the taper technology of the inner cladding and the middle cladding respectively; the end face of the other end of the triple-cladding optical fiber is located at the back focus of the optical antenna (1), and on this end face, the core output end face a' is located at the center of the annular inner cladding incident end face b; the optical splitting channel (6) of the core (2) passes through the inner cladding (3), the middle cladding (4) and the outer cladding (5) in sequence, one end of the optical splitting channel (6) is led out from the core (2), and the other end forms the monitoring light output end face a" on the surface of the outer cladding (5); A pump light overflow channel (7) is provided from the contact surface of the layer (4) and the outer cladding (5) to the outer surface of the outer cladding (5); a single-mode optical fiber is connected between the laser diode light outlet and the fiber core incident end face a, and the core diameter of the single-mode optical fiber is the same as the core diameter of the fiber core (2); a multi-mode optical fiber is connected between the inner cladding layer output end face b' and the light inlet of the photodiode, and the core diameter of the multi-mode optical fiber is the same as the diameter of the inner cladding layer output end face b'; an optical fiber is connected between the pump laser diode and the middle cladding layer incident end face c, and the core diameter of the optical fiber is the same as the diameter of the middle cladding layer incident end face c; an optical fiber is connected between the monitoring light output end face a" and the light inlet of the monitoring photodiode, and the core diameter of the optical fiber is the same as the diameter of the monitoring light output end face a".

2. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: The physical layer interface is an Ethernet physical layer interface module.

3. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: The output wavelength of the laser diode is 1550nm and the optical power is 5mW.

4. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: The photodiode is an indium gallium arsenide photodiode.

5. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: The optical antenna (1) is a beam shaping lens group composed of five spherical lenses, which realizes the collimated output of the transmitted communication data optical signal and the converged input of the received communication data optical signal. The aperture is 86mm and the effective light aperture is 80mm. Each lens is coated with a broadband anti-reflection and anti-transmission film in the 1550nm working band.

6. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: The optical fiber connecting the monitoring light emitting end face a" and the monitoring photodiode adopts a single-mode optical fiber.

7. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: An isolator is installed on the single-mode optical fiber path between the laser diode and the triple-clad optical fiber, and between the triple-clad optical fiber and the monitoring photodiode. This can prevent reflections from the device and solder joints, reduce the noise index of the triple-clad optical fiber, and increase stability.

8. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: The optical fiber between the conduction pump laser diode and the incident end face c of the middle cladding is a multimode optical fiber, which can transmit sufficient light energy.

9. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: The pump laser diode is a distributed feedback laser diode with a built-in Bragg grating, side emission, an output wavelength of 980nm, and an optical power of 600mW.

10. The single-mode and multi-mode coaxial transceiver kilometer-level wireless optical communication device according to claim 1, characterized in that: The core (2), inner cladding (3) and middle cladding (4) of the triple-cladding optical fiber are all made of quartz glass. The laser working substance doped in the middle cladding (4) is erbium with a lasing wavelength of 1550nm. The outer cladding (5) is a polymer coating.

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