A FSO and terahertz signal integrated transmission system and method based on a single transmitter

Abstract

The invention discloses an integrated transmission system and method of FSO and terahertz signals based on a single transmitter, comprising: a transmitting end, a terahertz receiving end and an FSO receiving end, wherein the transmitting end comprises: an arbitrary waveform generator for generating a baseband signal, an IQ modulator for modulating the baseband signal onto an optical carrier; an optical coupler for combining two beams of light into one beam, an optical fiber transmission module for transmitting optical signals, an integrated antenna and a silicon lens single-row carrier photodiode for simultaneously generating FSO and terahertz signals, and a lens for focusing FSO and terahertz signals; the receiving end comprises: a receiver for receiving FSO; an erbium-doped fiber amplifier for enhancing signals after optical fiber transmission; an integrated coherent optical receiver for receiving optical signals; the terahertz receiving end mainly comprises a low-noise amplifier, a terahertz mixer and an oscilloscope; the invention realizes the integrated transmission of FSO and terahertz of a single transmitter, and greatly reduces the complexity and weight of the transmitter.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber-wireless (Radio-over-Fiber, ROF) communication systems, and specifically relates to an FSO and terahertz signal integrated transmission system and method based on a single transmitter. Background Art

[0002] In recent years, free space optical communication (FSO) has been a hot topic in satellite-to-ground communication, inter-satellite communication and wireless access network research. It has the advantages of rich spectrum resources, no need for spectrum authorization, high spectrum efficiency, narrow beam angle and low spatial loss. In point-to-point communication, the beam angle makes FSO almost unaffected by multipath effects, so that low-complexity DSP algorithms can be used to recover demodulation. However, FSO is greatly affected by atmospheric weather, and the attenuation coefficient reaches 58-220dB / km in dense fog. On the other hand, its penetration ability is very poor and it can hardly propagate around any building. In contrast, terahertz has certain penetration ability and good potential rate. According to actual experimental measurements, it can be transmitted for several kilometers even in fog and rain, which is beyond the reach of FSO. On the other hand, terahertz transmission often requires higher power, and the changes in the transmission channel are more unstable than FSO. Combining FSO algorithm and terahertz architecture for wireless transmission can effectively expand the next-generation wireless network architecture and obtain greater broadband wireless transmission capabilities under various environmental conditions. According to the current reports, FSO and terahertz have achieved integrated transmission, but it requires two independent terahertz and FSO equipment. If the hardware of FSO and terahertz can be integrated and shared, it will greatly reduce the complexity and weight of the transmitter. Summary of the invention

[0003] In view of the above situation, the purpose of the present invention is to provide an integrated transmission system of free-space optical communication and terahertz signals based on a single transmitter, which does not require the use of two sets of transmitting equipment at the same time, namely, a terahertz signal transmitter and an FSO transmitter. A single-row carrier photodiode with an integrated antenna and a silicon lens is used to beat frequency generate a terahertz signal. At the same time, a silicon lens is used to converge the optical signal leaked from the single-row carrier photodiode, so that the hardware of free-space optical communication and terahertz communication can be integrated and shared, greatly reducing the complexity and weight of the transmitter.

[0004] Technical solution:

[0005] In the first aspect, a FSO and terahertz signal integrated transmission system based on a single transmitter is described in the order of signal transmission direction, including:

[0006] (1) Signal sending end:

[0007] an arbitrary waveform generator (AWG) to generate the baseband signal;

[0008] two electrical amplifiers (EA) for transmission loss compensation;

[0009] Two external cavity lasers (ECL), denoted as ECL1 and ECL2, where ECL1 outputs continuous light waves as the light source and is modulated afterwards, ECL2;

[0010] An I / Q modulator to modulate the signal;

[0011] a polarization-maintaining erbium-doped fiber amplifier (PM-EDFA) to enhance the optical signal;

[0012] A polarization-maintaining optical coupler (PM-OC) to combine the two optical signals;

[0013] A single-carrier photodiode (UTC-PD) with integrated antenna and silicon lens is used to beat-frequency generate terahertz signals, and a silicon lens is used to focus the optical signal leaked from the single-carrier photodiode;

[0014] A lens is used to focus the optical and electrical signal power between the antennas.

[0015] (2) FSO Receiver

[0016] An FSO receiver for receiving FSO;

[0017] an erbium-doped fiber amplifier (EDFA), which is used to enhance the signal after fiber transmission;

[0018] an integrated coherent receiver (ICR) for receiving optical signals;

[0019] An oscilloscope (OSC) captures the amplified signal and observes the signal's time domain and frequency domain diagrams.

[0020] (3) Terahertz receiving end

[0021] a receiving antenna for receiving terahertz signals;

[0022] a low-noise amplifier to boost the terahertz signal;

[0023] a terahertz mixer for down-converting the terahertz signal into an intermediate frequency signal;

[0024] An oscilloscope is used to capture the amplified signal and observe the time domain and frequency domain diagrams of the signal.

[0025] In the second aspect, a single-transmitter-based FSO and terahertz signal integrated transmission method uses a single-row carrier photodiode with an integrated antenna and a silicon lens to simultaneously generate terahertz signals and optical signals, so that the hardware of free-space optical communication and terahertz communication can be integrated and shared. The specific steps are as follows:

[0026] An arbitrary waveform generator is used to generate the baseband signal, and two parallel electrical amplifiers are used to compensate for transmission losses;

[0027] Using external cavity laser as optical carrier for signal modulation process;

[0028] Performing I / Q modulation on the baseband signal using an I / Q modulator;

[0029] The generated optical signal is amplified using an erbium-doped fiber amplifier and transmitted through a standard single-mode optical fiber;

[0030] A second external cavity laser is used to generate local oscillator light.

[0031] Use an optical coupler to combine the signal light and the local oscillator light into one beam of light;

[0032] Using integrated antenna and silicon lens single-row carrier photodiode to beat the signal, wireless terahertz signal and optical signal are generated simultaneously;

[0033] Use lenses to focus the power of transmitted and received signals;

[0034] The optical signal is received by an FSO receiver, transmitted through a single-mode optical fiber, amplified by a fiber amplifier, and finally received by an integrated coherent optical receiver;

[0035] A terahertz receiver is used to receive the terahertz signal. The terahertz signal is received through a terahertz antenna, first amplified by a low-noise amplifier, then down-converted into an intermediate frequency signal by a terahertz mixer, and finally captured by an oscilloscope.

[0036] Beneficial effects: The present invention utilizes a free-space optical communication and terahertz signal integrated transmission system based on a single transmitter, which has the characteristics of low complexity, light weight, simple structure, etc. This system mainly uses an integrated antenna single-line carrier photodiode to generate optical and electrical signals at the same time, greatly reducing the complexity of the transmitter, simplifying the transmitter structure, avoiding the simultaneous use of a complex terahertz signal transmitter and an FSO transmitter, and reducing system costs. This invention is a reliable solution for future satellite communications and 6G wireless backhaul. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the architecture of an FSO and terahertz signal integrated transmission system and method based on a single transmitter of the present invention.

[0038] Numbers in the figure: 1 arbitrary waveform generator AWG; 2, 22 are electrical amplifiers, 3, 33 are external cavity laser ECL1; 4 is IQ modulator; 5 single-mode optical fiber; 6 polarization-maintaining erbium-doped fiber amplifier; 7 is polarization-maintaining optical coupler PM-OC; 8 is integrated antenna single-row carrier photodiode; 9 is lens; 10 is terahertz receiving antenna; 11 is low-noise amplifier; 12 is terahertz mixer; 13 is oscilloscope; 14 is FSO receiver; 15 is erbium-doped fiber amplifier; 16 is integrated coherent optical receiver; 17 is oscilloscope. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1:

[0041] like Figure 1 As shown, a FSO and terahertz signal integrated transmission system based on a single transmitter includes: a signal transmitting end, an FSO receiving end and a terahertz receiving end;

[0042] The signal sending end is composed of the following:

[0043] an arbitrary waveform generator to generate baseband signals;

[0044] Two electrical amplifiers, including a first electrical amplifier and a second electrical amplifier, perform transmission loss compensation;

[0045] two external cavity lasers, denoted as a first external cavity laser and a second external cavity laser, wherein the first external cavity laser outputs a continuous light wave as a light source and is subsequently modulated by the second external cavity laser;

[0046] An I / Q modulator to modulate the signal;

[0047] a polarization-maintaining erbium-doped fiber amplifier to boost the optical signal;

[0048] A polarization-maintaining optical coupler, used to combine two optical signals;

[0049] A single-row carrier photodiode with an integrated antenna and silicon lens is used to beat frequency generate wireless terahertz signals, and a silicon lens is used to focus the optical signal leaked from the single-row carrier photodiode;

[0050] A lens to focus the optical and electrical signal power between the antennas;

[0051] The FSO receiving end is composed of the following:

[0052] An FSO receiver for receiving FSO;

[0053] an erbium-doped fiber amplifier, used to boost the signal after fiber transmission;

[0054] an integrated coherent optical receiver for receiving optical signals;

[0055] An oscilloscope to capture the amplified signal and observe the signal in the time domain and frequency domain;

[0056] The terahertz receiving end is composed of the following:

[0057] a receiving antenna for receiving terahertz signals;

[0058] a low-noise amplifier to boost the terahertz signal;

[0059] a terahertz mixer for down-converting the terahertz signal into an intermediate frequency signal;

[0060] An oscilloscope is used to capture the amplified signal and observe the time domain and frequency domain diagrams of the signal.

[0061] In one embodiment, Figure 1 As shown, the terahertz mixer is integrated by a local oscillator, a frequency multiplier, a mixer, and a low-noise amplifier.

[0062] Embodiment 2:

[0063] A method for integrated transmission of FSO and terahertz signals based on a single transmitter is implemented by using the integrated transmission system according to any one of claims 1 to 2, using a single-row carrier photodiode with an integrated antenna and a silicon lens to simultaneously generate a terahertz signal and an optical signal, so that the hardware of free space optical communication and terahertz communication can be integrated and shared, and the specific steps are as follows:

[0064] An arbitrary waveform generator is used to generate the baseband signal, and two parallel electrical amplifiers are used to compensate for transmission losses;

[0065] Using external cavity laser as optical carrier for signal modulation process;

[0066] Performing I / Q modulation on the baseband signal using an I / Q modulator;

[0067] The generated optical signal is amplified using an erbium-doped fiber amplifier and transmitted through a standard single-mode optical fiber;

[0068] A second external cavity laser is used to generate local oscillator light.

[0069] Use an optical coupler to combine the signal light and the local oscillator light into one beam of light;

[0070] Using integrated antenna and silicon lens single-row carrier photodiode to beat the signal, wireless terahertz signal and optical signal are generated simultaneously;

[0071] Use lenses to focus the power of transmitted and received signals;

[0072] The optical signal is received by an FSO receiver, transmitted through a single-mode optical fiber, amplified by a fiber amplifier, and finally received by an integrated coherent optical receiver;

[0073] A terahertz receiver is used to receive the terahertz signal. The terahertz signal is received through a terahertz antenna, first amplified by a low-noise amplifier, then down-converted into an intermediate frequency signal by a terahertz mixer, and finally captured by an oscilloscope.

[0074] In one embodiment, Figure 1 As shown, the silicon lens single-row carrier photodiode beats the frequency to generate a wireless terahertz signal electrical signal, and the silicon lens is used to converge the optical signal escaping from the single-row carrier photodiode.

[0075] In one embodiment, Figure 1 As shown, the fiber amplifier and the light are an erbium-doped fiber amplifier and a standard single-mode fiber, respectively.

[0076] In one embodiment, Figure 1 As shown, the laser is used as a local oscillator light source.

[0077] Working principle: An arbitrary waveform generator is used at the signal transmitting end to generate the baseband signal, and two parallel electrical amplifiers are used to compensate for the transmission loss. The first external cavity laser is used as the light source, and the continuous wave light wave generated is modulated by the baseband signal through the I / Q modulator. The output optical signal of the I / Q modulator is amplified by a polarization-maintaining erbium-doped fiber amplifier to compensate for the insertion loss of the modulator. After the optical signal is transmitted through a single-mode optical fiber, it is coupled with the continuous wave generated by the second external cavity laser through a polarization-maintaining optical coupler. The coupled optical signal enters the variable optical attenuator to change the optical power. The optical signal is input into a single-row carrier photodiode with an integrated antenna and a silicon lens, and an optical signal and a terahertz signal are generated at the same time. The optical signal and the terahertz signal are sent out through the antenna transmitting end for wireless link transmission.

[0078] At the receiving end, the FSO and terahertz signals are received simultaneously by independent receivers. The optical signal is received by the FSO receiver, then pre-amplified by the erbium-doped fiber amplifier and sent to the integrated coherent receiver, which is received by the digital oscilloscope, and the FSO transmission is completed. The terahertz signal is first focused by the lens and then received by the terahertz antenna. The received terahertz signal is first amplified by a low-noise amplifier to enhance the signal before down-conversion. The local oscillator drives the terahertz mixer for down-conversion. The down-converted intermediate frequency signal is amplified by the low-noise amplifier and received by the digital oscilloscope, and the terahertz signal transmission is completed.

[0079] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. An integrated transmission system for FSO and terahertz signals based on a single transmitter, characterized in that: include: Signal transmitter, FSO receiver and terahertz receiver; The signal sending end is composed of the following: an arbitrary waveform generator to generate baseband signals; Two electrical amplifiers, including a first electrical amplifier and a second electrical amplifier, perform transmission loss compensation; two external cavity lasers, denoted as a first external cavity laser and a second external cavity laser, wherein the first external cavity laser outputs a continuous light wave as a light source and is subsequently modulated by the second external cavity laser; An I / Q modulator to modulate the signal; a polarization-maintaining erbium-doped fiber amplifier to boost the optical signal; A polarization-maintaining optical coupler, used to combine two optical signals; A single-row carrier photodiode with an integrated antenna and silicon lens is used to beat frequency generate wireless terahertz signals, and a silicon lens is used to focus the optical signal leaked from the single-row carrier photodiode; A lens to focus the optical and electrical signal power between the antennas; The FSO receiving end is composed of the following: An FSO receiver for receiving FSO; an erbium-doped fiber amplifier, used to boost the signal after fiber transmission; an integrated coherent optical receiver for receiving optical signals; An oscilloscope to capture the amplified signal and observe the signal in the time domain and frequency domain; The terahertz receiving end is composed of the following: a receiving antenna for receiving terahertz signals; a low-noise amplifier to boost the terahertz signal; a terahertz mixer for down-converting the terahertz signal into an intermediate frequency signal; An oscilloscope is used to capture the amplified signal and observe the time domain and frequency domain diagrams of the signal.

2. The FSO and terahertz signal integrated transmission system based on a single transmitter according to claim 1, characterized in that: The terahertz mixer is integrated by combining a local oscillator, a frequency multiplier, a mixer and a low-noise amplifier.

3. A single-transmitter FSO and terahertz signal integrated transmission method, characterized in that: The integrated transmission system according to any one of claims 1 to 2 is used to realize the terahertz signal and the optical signal simultaneously by using a single-row carrier photodiode with an integrated antenna and a silicon lens, so that the hardware of free-space optical communication and terahertz communication can be integrated and shared, and the specific steps are as follows: An arbitrary waveform generator is used to generate the baseband signal, and two parallel electrical amplifiers are used to compensate for transmission losses; Using external cavity laser as optical carrier for signal modulation process; Performing I / Q modulation on the baseband signal using an I / Q modulator; The generated optical signal is amplified using an erbium-doped fiber amplifier and transmitted through a standard single-mode optical fiber; A second external cavity laser is used to generate local oscillator light; Use an optical coupler to combine the signal light and the local oscillator light into one beam of light; Using integrated antenna and silicon lens single-row carrier photodiode to beat the signal, wireless terahertz signal and optical signal are generated simultaneously; Use lenses to focus the power of transmitted and received signals; The optical signal is received by an FSO receiver, transmitted through a single-mode optical fiber, amplified by a fiber amplifier, and finally received by an integrated coherent optical receiver; A terahertz receiver is used to receive the terahertz signal. The terahertz signal is received through a terahertz antenna, first amplified by a low-noise amplifier, then down-converted into an intermediate frequency signal by a terahertz mixer, and finally captured by an oscilloscope.

4. The method for integrated transmission of FSO and terahertz signals based on a single transmitter according to claim 3, characterized in that: The silicon lens single-line carrier photodiode beats the frequency to generate wireless terahertz signal electrical signals, and at the same time uses the silicon lens to converge the optical signals escaping from the single-line carrier photodiode.

5. The method for integrated transmission of FSO and terahertz signals based on a single transmitter according to claim 3, characterized in that: The fiber amplifier and light are erbium-doped fiber amplifier and standard single-mode fiber, respectively.

6. The method for integrated transmission of FSO and terahertz signals based on a single transmitter according to claim 3, characterized in that: The laser is used as a local oscillator light source.

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