Novel laser signal modulation and demodulation device

Abstract

The invention discloses a novel laser signal modulation and demodulation device which comprises a pulse laser, a pulse width extraction system, a data caching system, a clock and data retiming system, a lithium niobate modulator, a signal amplification system, an optical fiber collimator and a light beam expander. Through clock matching and reconstruction, an electric signal carrying information is loaded to each pulse of the pulse laser, the amplitude of the pulse is modulated so as to carry the information, the pulse laser carrying the information is diverged into space to be transmitted, the space optical communication scheme of the pulse laser enables the modulated optical signal to be extremely high in intensity, and the space optical communication efficiency is improved. The transmission distance of optical signals in the space is greatly increased, and the communication range of spatial light is expanded.

Description

Technical Field

[0001] The invention relates to the field of optical communication, and in particular to a novel laser signal modulation and demodulation device. Background Art

[0002] In the process of optical communication, the energy of the unmodulated optical carrier occupies a part of the total energy of the laser. Therefore, part of the laser energy does not transmit the signal, and the peak power of the laser used in the communication field is generally low. Therefore, if the modulated optical signal is spread into space for transmission and communication, the transmission distance is subject to certain restrictions, which is manifested as limited communication distance.

[0003] Space optical communication is a technology that uses free space to transmit optical signals. Compared with microwave communication, free space laser communication has a higher transmission rate; laser communication is not affected by electromagnetic interference, so it performs well in complex environments; unlike radio frequency bands, laser communication is not limited by the spectrum. Free space laser communication has a wide range of application value in scenarios such as emergency communication, satellite-to-ground communication and inter-satellite communication, providing more solutions for communication.

[0004] Common modulation methods include intensity modulation, pulse position modulation, and binary phase shift keying modulation. Intensity modulation is simple to implement, but is limited by the average optical power, shortens the transmission distance, and is highly sensitive to environmental changes. Pulse lasers can use very small average power to obtain larger pulse power, thereby improving data transmission efficiency. Pulse position modulation is a modulation signal that only changes the time when each pulse in the carrier pulse series is generated, without changing its shape and amplitude. The change in the time of each pulse is proportional to the amplitude of the modulation signal voltage and has nothing to do with the frequency of the modulation signal. This modulation is called pulse position modulation. Pulse position modulation has the advantages of high energy efficiency and strong anti-interference ability in specific applications, but its low bandwidth efficiency, high time synchronization requirements, and high peak power requirements limit its wide application.

[0005] Therefore, there is an urgent need for a new type of laser signal modulation and demodulation device that can solve the low data transmission efficiency of continuous laser communication, which is limited by the average optical power. The use of pulsed laser communication can improve data transmission efficiency, but the commonly used pulse position modulation has the problems of high time synchronization requirements and complex demodulation system. Summary of the invention

[0006] The purpose of the present invention is to provide a new type of laser signal modulation and demodulation device, which utilizes the characteristic of pulse laser that it can obtain a larger pulse power with a very small average power, modulates the amplitude of the pulse, and makes the space optical communication system have strong anti-interference ability and a longer transmission distance, so as to solve the problems existing in the above-mentioned prior art.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a novel laser signal modulation and demodulation device, comprising:

[0009] A pulse laser, used to generate pulse laser as a carrier to be modulated;

[0010] A pulse width extraction system is used to extract the pulse width of the pulse laser and use it as a new clock signal to reorganize the electrical signal in the buffer area;

[0011] A data buffer system for buffering electrical signals that are not loaded onto the pulse laser;

[0012] A clock and data retiming system, used to retime the extracted new clock signal with the electrical signal data and reshape to generate a clock signal having the pulse width of the pulse laser;

[0013] A lithium niobate modulator for driving a clock signal having a pulse width of a pulsed laser generated by a clock and data retiming system;

[0014] A signal amplification system, used to optically amplify a modulated pulse laser carrying a signal;

[0015] Fiber collimator, used to convert laser light in optical fiber into parallel light;

[0016] A beam expander is used to expand a parallel light beam and launch it into space for transmission.

[0017] Preferably, the pulse laser is a solid-state Q-switched laser.

[0018] Preferably, the lithium niobate modulator adopts an MZ modulator structure, and its upper and lower arms use sheet lithium niobate, and transparent thin film electrodes are plated in directions corresponding to the optical axis of the sheet lithium niobate crystal, and the transparent thin film electrodes are connected to the control circuit.

[0019] Preferably, the signal amplification system adopts a semiconductor optical amplifier.

[0020] The present invention also provides a novel laser signal modulation and demodulation method, comprising the following steps:

[0021] S1. The pulse laser generated by the pulse laser is used as the carrier to be modulated. The pulse width should match the modulation rate and the received electrical signal is loaded onto a single pulse.

[0022] S2. The pulse width extraction system extracts the pulse width of the pulse laser. The pulse width is stable when the laser is in working state. The extracted pulse width information is reintegrated into a new clock signal for subsequent signal reorganization.

[0023] S3. The data cache system caches the electrical signal that is not loaded on the pulse laser. The cache area is used to solve the problem caused by the mismatch between the clock and pulse width of the electrical signal;

[0024] S4. Retiming the extracted pulse width information of the pulsed laser using the clock and data retiming system and the electrical signal data to form a clock signal having the pulse width of the pulsed laser;

[0025] S5. Using a clock signal with a pulse width of a pulsed laser as a driving signal for a lithium niobate modulator, using an MZ modulator structure, and using flake lithium niobate for phase modulation on the upper and lower arms to achieve amplitude modulation;

[0026] S6. The amplified optical signal enters the optical fiber collimator, which converts the light beam into parallel light;

[0027] S7. The parallel light passes through the beam expander, which expands the parallel light beam and emits it into space for transmission.

[0028] Compared with the prior art, the present invention has achieved the following beneficial technical effects:

[0029] 1. Pulse lasers can use small average power to obtain high pulse power signals, carry data by modulating the pulse amplitude, improve data transmission efficiency, and reduce system power consumption.

[0030] 2. Pulse lasers have large peak power, so their anti-interference ability is greatly enhanced, which increases the data transmission distance and expands the communication range of spatial light. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 A schematic diagram of the structure of a novel laser signal modulation and demodulation device provided by the present invention;

[0033] Figure 2 A schematic diagram of the relationship between pulse laser field intensity and time for a novel laser signal modulation and demodulation device provided by the present invention;

[0034] Figure 3 A digital signal-time schematic diagram of a novel laser signal modulation and demodulation device provided by the present invention;

[0035] Figure 4A schematic diagram of the relationship between the pulsed laser field intensity and time of a novel laser signal modulation and demodulation device provided by the present invention after passing through a modulator;

[0036] Figure 5 A schematic diagram of a reorganized clock signal of a novel laser signal modulation and demodulation device provided by the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0038] The purpose of the present invention is to provide a novel laser signal modulation and demodulation device to solve the problems existing in the prior art.

[0039] The core of the present invention is to load the electrical signal carrying information onto each pulse of the pulse laser through clock matching and reconstruction, modulate the amplitude of the pulse to carry information, and radiate the pulse laser carrying information into space for transmission.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Embodiment 1:

[0042] This embodiment provides a novel laser signal modulation and demodulation device, such as Figure 1-5 As shown, it includes a pulse laser 1, a pulse width extraction system 2, a data cache system 3, a clock and data retiming system 4, a lithium niobate modulator 5, a signal amplification system 6, a fiber collimator 7, and a beam expander 8, wherein:

[0043] Pulse laser 1 is a solid-state Q-switched laser with a repetition frequency in the kHz range. It emits stable pulsed lasers through Q-switching technology. The pulsed laser generated by pulse laser 1 serves as the carrier to be modulated. The pulse width remains stable when the laser is in operation. The pulse width should match the modulation rate to facilitate the subsequent loading of the received electrical signal onto a single pulse.

[0044] Of course, in other embodiments, the pulse laser 1 may also be an optical frequency comb laser, whose pulse width is extremely small, and therefore requires a subsequent modulator to match the electrical signal buffer processing.

[0045] The pulse width extraction system 2 will extract the pulse width of the pulse laser 1. The pulse width remains stable when the pulse laser 1 is in working state. The extracted pulse width information is reintegrated into a new clock signal for use in subsequent signal reorganization. The pulse width information of the pulse laser 1 is basically known. The function of the pulse width extraction system 2 is to test the pulse width information of the pulse laser 1 in this specific application environment, perform small-amplitude calibration, and enhance the stability of the entire system.

[0046] The data cache system 3 is used to cache the electrical signal that is not loaded onto the pulse laser. The cache area is used to solve the problem caused by the mismatch between the clock and pulse width of the electrical signal. In addition, the pulse width information, input data rate, and modulation rate of the lithium niobate modulator are required to match each other to reduce the complexity of the data cache system. The input electrical signal is consistent with the repetition frequency of the pulse laser 1 and maintained at the kHz level.

[0047] The clock and data retiming system 4 extracts and corrects the intact pulse laser pulse width information and the electrical signal data from the pulse laser 1 to retime the signal to form a signal with the pulse width of the pulse laser.

[0048] The signal generated by the clock and data retiming system 4 will be used as the driving signal of the lithium niobate modulator 5. The lithium niobate crystal has a significant electro-optical effect. When an electric field is applied, its refractive index will change. When the linear electro-optical effect is used, the change in the refractive index is linearly related to the external electric field. In this embodiment, a sheet lithium niobate material is used, and a transparent thin film electrode is plated in the direction corresponding to the optical axis of the sheet lithium niobate crystal. The electrode is connected to the control circuit. The circuit realizes the refractive index change by changing the voltage applied to the transparent thin film electrode. The lithium niobate modulator 5 adopts the structure of an MZ modulator. The input light beam enters the upper and lower arm structures after beam splitting. The upper and lower arms use the above-mentioned sheet lithium niobate to change the refractive index and generate an optical path difference for phase modulation. After passing through the combiner, pulse amplitude modulation is realized.

[0049] The modulated pulse laser carrying the signal enters the signal amplification system 6 for optical amplification. The signal amplification system 6 adopts a semiconductor optical amplifier (SOA) structure to achieve signal amplification, improve the optical power of the modulated signal, and increase the transmission distance of the spatial light. This embodiment uses a solid Q-switched laser with a repetition frequency of the kHz order, and the gain recovery time meets the use conditions of the SOA. It should be noted that the gain saturation parameters of the SOA should meet the requirements.

[0050] If the pulse laser 1 in other embodiments adopts an optical frequency comb laser, the SOA gain recovery time will affect the signal quality, so it is necessary to adjust the solution of the signal amplification system 6.

[0051] The light beam directly output by the optical fiber is usually divergent, and the optical fiber collimator 7 can convert this divergent light beam into a parallel light beam, thereby reducing the diffusion and attenuation of the light beam during transmission. In this embodiment, the optical signal amplified by the signal amplification system 6 is connected to the optical fiber collimator 7 to convert the light beam in the optical fiber into parallel light.

[0052] The parallel light output by the optical fiber collimator 7 passes through the beam expander 8, which expands the parallel light beam and emits it into space for transmission.

[0053] The spatial light formed by the beam expander 8 carries the signal for transmission, and has the characteristics of high peak power, strong anti-interference ability and greatly increased communication distance.

[0054] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A novel laser signal modulation and demodulation device, characterized in that: include: A pulse laser, used to generate pulse laser as a carrier to be modulated; A pulse width extraction system is used to extract the pulse width of the pulse laser and use it as a new clock signal to reorganize the electrical signal in the buffer area; A data buffer system for buffering electrical signals that are not loaded onto the pulse laser; A clock and data retiming system, used to retime the extracted new clock signal with the electrical signal data and reshape to generate a clock signal having the pulse width of the pulse laser; A lithium niobate modulator for driving a clock signal having a pulse width of a pulsed laser generated by a clock and data retiming system; A signal amplification system, used to optically amplify a modulated pulse laser carrying a signal; Fiber collimator, used to convert laser light in optical fiber into parallel light; A beam expander is used to expand a parallel light beam and launch it into space for transmission.

2. The novel laser signal modulation and demodulation device according to claim 1 is characterized in that: The pulse laser is a solid-state Q-switched laser.

3. The novel laser signal modulation and demodulation device according to claim 1 is characterized in that: The lithium niobate modulator adopts an MZ modulator structure, and its upper and lower arms use sheet lithium niobate. Transparent thin film electrodes are plated in directions corresponding to the optical axis of the sheet lithium niobate crystal, and the transparent thin film electrodes are connected to a control circuit.

4. The novel laser signal modulation and demodulation device according to claim 1 is characterized in that: The signal amplification system adopts a semiconductor optical amplifier.

5. A novel laser signal modulation and demodulation method, characterized in that: The following steps are involved: S1. The pulse laser generated by the pulse laser is used as the carrier to be modulated. The pulse width should match the modulation rate and the received electrical signal is loaded onto a single pulse. S2. The pulse width extraction system extracts the pulse width of the pulse laser. The pulse width is stable when the laser is in working state. The extracted pulse width information is reintegrated into a new clock signal for subsequent signal reorganization. S3. The data cache system caches the electrical signal that is not loaded on the pulse laser. The cache area is used to solve the problem caused by the mismatch between the clock and pulse width of the electrical signal; S4. Retiming the extracted pulse width information of the pulsed laser using the clock and data retiming system and the electrical signal data to form a clock signal having the pulse width of the pulsed laser; S5. Using a clock signal with a pulse width of a pulsed laser as a driving signal for a lithium niobate modulator, using an MZ modulator structure, and using flake lithium niobate for phase modulation on the upper and lower arms to achieve amplitude modulation; S6. The amplified optical signal enters the optical fiber collimator, which converts the light beam into parallel light; S7. The parallel light passes through the beam expander, which expands the parallel light beam and emits it into space for transmission.

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