CN104300343B - Microwave and harmonic wave generating device based on optical phase-locked loop - Google Patents

Abstract

The invention belongs to microwave and harmonic wave generating devices in the field of photoelectronic technology and discloses a microwave and harmonic wave generating device based on an optical phase-locked loop. The microwave and harmonic wave generating device based on the optical phase-locked loop comprises a laser sourer generator, a laser coupling mirror, the optical phase-locked loop, and a second or multiple harmonic generation harmonic wave output port of a microwave signal. The optical phase-locked loop is formed by connecting a tunable multiple-longitudinal-mode solid laser, an optical fiber coupling mirror, an input end of an optical fiber dense wavelength division multiplexer, two adjacent output optical fibers of the optical fiber dense wavelength division multiplexer, an optical fiber beam combiner, a photoelectric converter, a microwave frequency mixer with a microwave signal input port, a low frequency amplifier and a loop filter in series. The second or multiple harmonic generation harmonic wave output port of the microwave signal is formed by connecting any two output optical fibers in output optical fibers of the optical fiber dense wavelength division multiplexer, the optical fiber beam combiner and the photoelectric converter in series. The microwave and harmonic wave generating device based on the optical phase-locked loop has the advantages that a circuit structure is advanced, the power range of processing input microwave signals is expanded while requirements and costs of optical and electronic components and devices are reduced,, harmonic waves with different degrees of harmonic generation can be achieved by adopting the same drive voltage, the processing ability and the processing effect of weak microwave signals are effectively improved, and harmonic generation and multiple harmonic generation harmonic waves can be generated.

Description

A microwave harmonic generation device based on optical phase-locked loop

technical field

The invention relates to a microwave harmonic generating device in the field of optoelectronic technology, in particular to a microwave harmonic generating device based on an optical phase-locked loop.

Background technique

As the carrier of broadband information transmission, microwave has broad application prospects in space communication. Microwave harmonics mean higher frequency microwaves or even millimeter waves and THz waves, which can be used as carrier frequencies to obtain greater information capacity in communication. However, traditional microwave harmonics are realized by means of microwave electronics, mainly including fundamental wave mixing and harmonic mixing. With the increase of microwave frequency, especially for microwaves higher than 25 GHz, the difficulty and cost of obtaining harmonics by microwave electronics methods continue to increase.

In recent years, researchers have proposed to generate microwave/millimeter wave harmonics by laser intensity modulation. The optical millimeter wave is then subjected to photoelectric conversion, and the sidebands of the optical microwave/optical millimeter wave beat each other to obtain the harmonic signal of the input microwave/millimeter wave signal. This solution has the problem of high driving voltage (requires high input signal power), and it can usually only be used to generate even-octave harmonics. Chinese invention patent "Multi-frequency millimeter-wave generation device based on single-drive Mach-Zehnder modulator" (application number: 201310211180.3) discloses a multi-frequency millimeter-wave generator based on single-drive Mach-Zehnder (electro-optic) modulator , the device includes a (single longitudinal mode) laser, a polarization controller, a single-drive Mach-Zehnder modulator, a radio frequency signal source, a radio frequency signal amplifier, a regulated power supply, and a photodetector (photoelectric converter). By sending the radio frequency signal to the driving end of the single-drive Mach-Zehnder modulator, changing its driving voltage, and adjusting the bias voltage of the modulator, the target laser side frequency is obtained, and then the side frequency is photoelectrically converted to obtain a multiple Frequency millimeter waves, and an embodiment of realizing even frequency multiplied millimeter waves is given. Although this method can generate even frequency multiplied millimeter waves, the required driving (input) voltage is high (the input millimeter wave signal power is high), especially for input signals above 25GHz, the required driving (input) voltage is generally above 4V And the same order of frequency multiplication requires a certain driving voltage, that is, different orders of frequency multiplication require different fixed (constant) driving voltages; when the input millimeter wave signal is very weak (the driving voltage is extremely low), it needs to be performed in advance Multi-stage amplification is not only costly and difficult to implement, but also deteriorates the signal-to-noise ratio of the input signal. Therefore, the multi-frequency millimeter wave (harmonic wave) generating device is not suitable for processing weak millimeter wave signals.

Contents of the invention

The purpose of the present invention is to study and design a microwave harmonic generation device based on an optical phase-locked loop for the defects in the background technology, so as to change the circuit structure, reduce microwave circuits, and reduce the requirements and costs of optical and electronic components. , expand the power (strength) range of processing input microwave signals, and use the same driving voltage to realize harmonics of different orders of frequency multiplication, effectively improve the processing ability and effect of weak micro-wave signals, and can generate frequency multiplication and multiple Doubling harmonics and other purposes.

The solution of the present invention is aimed at the disadvantages of high cost and difficulty in implementation due to the different fixed high drive voltages (high input signal power) required by different orders of frequency doubling in the background technology. mode solid-state laser, fiber coupling mirror, fiber dense wavelength division multiplexer, fiber beam combiner, photodetector, microwave mixer, low frequency amplifier, loop filter, optical phase-locked loop formed in series, the two The beat frequency signals of adjacent laser longitudinal modes are phase-locked with the input microwave signals; the present invention obtains corresponding harmonics through the beat frequency signals of different longitudinal modes and the input microwave signals, which can generate both even-numbered frequency multiplier harmonics and Odd multiplier harmonics; thereby not only reducing the requirements for input signal power and optical and electronic components, but also effectively reducing the difficulty and cost of implementation. The present invention is: the longitudinal mode beams of different frequencies output by the multi-longitudinal mode solid-state laser are guided through the fiber coupling mirror and the fiber dense wavelength division multiplexer to respectively guide the longitudinal mode beams of different frequencies to the corresponding optical fiber dense wavelength division multiplexer. In the output fiber of the laser, the beat frequency signals of the laser longitudinal mode beams in any two adjacent output fibers are phase-locked with the input microwave signal through an optical phase-locked loop; due to the frequency interval of the adjacent longitudinal mode beams output by the laser (difference) is equal, then the longitudinal mode beam output by any two optical fibers with an interval (longitudinal mode order difference) equal to or greater than 2 is subjected to beat frequency and photoelectric conversion processing, and the double frequency and multiple times of the input microwave signal can be obtained frequency harmonics; the present invention realizes its inventive purpose with this. Thereby the present invention is based on the microwave harmonic generation device of optical phase-locked loop, it is characterized in that this microwave harmonic generation device comprises laser source generator and laser coupling mirror, is made of tunable multi-longitudinal mode solid-state laser, fiber coupling mirror, fiber dense wave The optical phase-locked loop formed by series connection of the input end of the multiplexer and its two adjacent output optical fibers, optical fiber combiner, photoelectric converter, microwave mixer with microwave signal input port, low-frequency amplifier, and loop filter, And the double frequency or multiple frequency harmonic output port of the (input) microwave signal formed in series by any other two output fibers in the output fiber of the optical fiber dense wavelength division multiplexer, the fiber combiner and the photoelectric converter; The laser light emitted by the laser generator is input into the tunable multi-longitudinal mode solid-state laser through the laser coupling mirror, and the microwave signal is input through the microwave signal input port of the microwave mixer.

The above-mentioned laser source generator is a semiconductor pump laser. The tunable multi-longitudinal-mode solid-state laser is a resonant cavity composed of front and rear cavity mirrors, a laser working substance placed in the resonant cavity, a piezoelectric ceramic and a piezoelectric driver that are close to the laser working substance, and A tunable short-cavity multi-longitudinal-mode solid-state laser composed of semiconductor cooling plates. And the front end face of described laser working substance is _an inclined plane, and front cavity mirror 2-2 is then corresponding inclined body; 65°, and the inclination angle θ ₂ between the front cavity mirror 2-2 and the upper surface (cold end plane) of the semiconductor refrigeration chip is 50°～80°.

The microwave harmonic generating device of the present invention is mainly a low-frequency circuit because the circuit used is mainly a low-frequency circuit, and the optical and electrical components used in the circuit are conventional and commercial components. Therefore, compared with the microwave electronics method, the microwave circuit used is more efficient. less, the overall cost of the device is low; the input signal of the low-frequency amplifier and the piezoelectric driver is a low-frequency signal (kHz order), and both high-gain and low-gain amplification are relatively easy to implement; therefore, the input microwave signal power ( Strength) low requirements, wide range (-50dBm ~ 22dBm), using the same drive voltage can achieve different orders of frequency multiplier harmonics; when processing low-power input signals, through the low-frequency amplifier and piezoelectric driver The adjustment of the gain and the parameters of the loop filter can maintain the normal and stable operation of the harmonic generation device; the invention can not only generate even-numbered frequency harmonics, but also be used to generate odd-numbered frequency harmonics. Therefore, it has an advanced circuit structure. While reducing the requirements and costs of optical and electronic components, it expands the power (strength) range of the input microwave signal, and the harmonics of different orders of frequency multiplication can be realized by using the same driving voltage. , which effectively improves the processing ability and effect of weak microwave signals, and can generate frequency multiplication and multi-frequency harmonics.

Description of drawings

Fig. 1 is the device of the present invention and embodiment 1 structural representation;

Fig. 2 is the structural representation of embodiment 2 of the device of the present invention;

In the figure: 1-1. Pump laser generator, 1-2. Laser coupling mirror, 2. Tunable multi-longitudinal mode solid-state laser, 2-1. Rear cavity mirror, 2-2. Front cavity mirror, 2-3 .Laser resonator, 2-4. Laser working substance, 2-5. Piezoelectric ceramics, 2-6. Piezoelectric driver, 2-7. Semiconductor cooler, 3. Fiber coupling mirror, 4. Optical fiber dense wavelength division Multiplexer, 4-1. Input optical fiber, 4-2.1, 4-2.2, 4-2.3, ..., 4-2.M, ..., 4-2.L, ..., 4-2.N: (No. 1 , 2, 3, ..., M, ... L, ..., N) output optical fiber, 5-1. Fiber combiner, 5-2. Fiber splitter, 6. Photoelectric converter (photodetector), 7 .Microwave mixer, 8. Low frequency amplifier, 9. Loop filter, 10. Input microwave signal, 11. Microwave (LM) double frequency harmonic (output), 12. Microwave double frequency harmonic (output) , θ ₁ . The inclination angle of the laser working material output surface, θ ₂ . The inclination angle of the front cavity mirror.

detailed description

In this embodiment: pump laser generator 1-1: semiconductor pump laser with model FL-FCSE01-3-976-105-0.15, wavelength 976nm, power 3W, manufactured by Xi'an Focuslight Technology Co., Ltd.;

Laser coupling mirror 1-2: model GCL-010201, focal length 19mm, manufactured by Daheng New Era Technology Co., Ltd.;

Rear cavity mirror 2-1: transmittance of 976nm laser is greater than 80%, reflectivity of C-band laser is greater than 98%; front cavity mirror 2-2: transmittance of C-band laser is 10%, reflectance of C-band laser The rate is 90%, produced by Daheng New Era Technology Co., Ltd.;

Laser working material 2-4: LGS-X Er-doped phosphate glass, with a refractive index of 1.53, a half-width of fluorescence of 29.9nm, and a length of 2mm in the light direction, produced by Chengdu Dongjun Laser Co., Ltd.;

Piezoelectric ceramics 2-5: model P-5H, thickness 0.5mm, Baoding Hongsheng Acoustic Electronic Equipment Co., Ltd.;

Piezoelectric drivers 2-6: model HFVA-41, output voltage 400V, Nanjing Fo Neng Technology Industrial Co., Ltd.

Semiconductor cooling chip 2-7: model TEC1-03115T125, Yuxian Zhongtian Electronics Co., Ltd.;

Fiber coupling lens 3: Model 352220, focal length 11mm, Wrightbass Optical Instrument (Shanghai) Co., Ltd.;

Optical fiber dense wavelength division multiplexer 4: model mics-16/25/G/PMF/0.4, adjacent channel frequency difference (interval) 25GHz, Beijing Jinkun Technology Co., Ltd.;

Optical fiber combiner 5-1 and optical fiber splitter 5-2: model PMFC-55-2-50-F-2222-LLLL-P-0.5, Guangyue Technology (Shenzhen) Co., Ltd.;

Photoelectric converter 6: This embodiment adopts a photoelectric detector with a model number of MR30-100A-S-K/DC and a bandwidth of 100 GHz produced by Hangzhou Huatai Optical Fiber Technology Co., Ltd.;

Microwave mixer 7: model NC1718C-1850, frequency band 18-50GHz, the Thirteenth Research Institute of China Electronics Group;

Low-frequency amplifier 8: model AD829, gain-bandwidth product 600MHz, produced by American Analog Devices;

Loop filter 9: model IFC-50B, 10MHz bandwidth, American Thorlabs company.

In the implementation mode:

Embodiment 1: the rear cavity mirror 2-1 and the front cavity mirror 2-2 form a laser resonator 2-3, and the laser working substance 2-4 is placed in the resonator 2-3; the piezoelectric ceramic sheet 2-5 is bonded It is fixed on the top surface of Er-doped phosphate glass (laser working substance) 2-4; the rear cavity mirror 2-1, the laser working substance 2-4 and the front cavity mirror 2-2 are placed on the semiconductor cooling plate 2-7 surface, each end face is parallel to and perpendicular to the upper surface (cold end plane) of the semiconductor cooling chip 2-7, and the rear cavity mirror 2-1 and the front cavity mirror 2-2 in the tunable multi-longitudinal mode solid-state laser 2 of this embodiment are thick Both are 1.0mm, 2.0mm high, and the distance between the two inner walls is 4.94mm. Er-doped phosphate glass (laser working material) 2-4 is 3.0mm long along the front and rear cavity mirrors, and the height and width are both 2.0mm; the pump The laser light emitted by the Pu laser generator 1-1 is converged by the coupling mirror 1-2, enters the laser working substance 2-4 through the rear cavity mirror 2-1, forms a multi-longitudinal mode beam through the laser resonator 2-3, and then After the front cavity mirror 2-2 is incident on the fiber coupling mirror 3, it is converged and coupled, and then enters the fiber dense wavelength division multiplexer 4 through the input fiber 4-1, and the corresponding longitudinal mode beams in the laser pass through the first and second output fibers respectively. 4-2.1 and 4-2.2 respectively enter the two input ends of the fiber combiner 5-1, and then enter the photoelectric converter (photodetector) 6 and microwave mixer 7 through the output end of the fiber combiner 5-1 At the same time, the microwave signal 10 is input by another input port of the microwave mixer 7, and the output signal processed by the microwave mixer 7 passes through the low-frequency amplifier 8, and then enters the loop filter 9, and the output signal of the loop filter 9 The output signal enters the tunable multi-longitudinal mode solid-state laser 2 through the piezoelectric driver 2-6 of the tunable multi-longitudinal mode solid-state laser; M=3, L=6 in Fig. 1) the output fiber is connected in series with another fiber combiner 5-1 and a photoelectric converter (photodetector) 6 to form a 3-fold harmonic signal output port.

In this embodiment: when the power of the laser output by the pumping laser generator 1-1 is high enough, a sufficiently high gain is generated in the laser working substance 2-4, thereby forming multi-longitudinal mode oscillations in the laser resonator, and the pumping The higher the optical power, the more the number of longitudinal modes; the multi-longitudinal mode output laser passes through the fiber coupling mirror 3, passes through the input fiber 4-1, and enters the optical fiber dense wavelength division multiplexer 4 to distribute each laser longitudinal mode to each output fiber 4- 2.1, 4-2.2, 4-2.3, 4-2.6, when the number of longitudinal modes is 6; follow the principle that the output channel spacing of the fiber dense wavelength division multiplexer should match the longitudinal mode spacing of the output laser, that is, the channel The frequency interval between them should be approximately equal to the frequency interval between the longitudinal modes to reduce the crosstalk between different channels. For example, if the frequency of the input microwave signal 10 is 25 GHz, both the channel spacing and the longitudinal mode spacing can be taken as 25 GHz; the 6 longitudinal modes generated by the laser can enter each output fiber (4-2.1 to 4-2.6) respectively. The frequency interval of the lasers in the output fibers 4-2.1 and 4-2.2 is 25 GHz, and after being combined by the fiber beam combiner 5-1, it is input to the photodetector 6, and the electrical signal converted into 25 GHz is input to the microwave mixer 7, and the input microwave After the signal 10 is mixed, a phase error signal is generated; the phase error signal is amplified by the low-frequency amplifier 8 and input to the loop filter 9 to generate a laser frequency control signal, and the control signal is amplified by the piezoelectric driver 2-6 and then input to the piezoelectric ceramic to form a closed The control loop realizes the phase locking of the input microwave signal 10 and two adjacent longitudinal mode beat signals; since the frequency intervals of the two adjacent longitudinal modes of the laser resonator are equal, the output fibers from the 3rd and 6th (4- 2.3, 4-2.6) respectively output the 3rd and 6th longitudinal mode, through the optical fiber beam combiner 5-1 and through the photoelectric converter (photoelectric detector) 6, output the beat frequency signals of the two longitudinal modes, that is, output 3-octave harmonic signal of microwave signal 10.

When the input microwave signal 10 is weak, the damping coefficient of the phase-locked loop can be adjusted within the range of 0.2 to 1 by adjusting the gain of the low-frequency amplifier 8 and the piezoelectric driver 2-6, and the parameters of the loop filter 9 , the normal and stable operation of the entire harmonic generating device can be maintained. Because the phase error signal output by the microwave mixer 7 is a low frequency signal (kHz order of magnitude), it is easier to amplify it; as: when the power of the input microwave signal 10 is -50dBm (corresponding to the input voltage 1mV), then The gain of the low-frequency amplifier 8 and the piezoelectric driver 2-6 can be adjusted to about 40dB; The gain can be adjusted to about 4dB.

Embodiment 2: Fig. 2 is the structural representation of the microwave harmonic generation device based on the optical phase-locked loop provided by the present invention, and the present embodiment sets the front end face of Er-doped phosphate glass (laser working material) 2-4 as inclined plane , Front cavity mirror 2-2 is then made as oblique body, and the inclination angle θ ₁ of the former and the upper surface (cold end plane) of semiconducting cooling plate 2-7 is 57 °, the latter (front cavity mirror 2-2) The inclination angle θ ₂ with the upper surface (cold end plane) of the semiconductive refrigeration sheet 2-7 is 66° in this embodiment. Utilizing the light transmission characteristics of the tilted output surface of Er-doped phosphate glass (laser working material) 2-4, the transmittance of horizontally polarized light can be greater than that of vertically polarized light, so that the resonance loss of horizontally polarized light is smaller than that of vertically polarized light, then The horizontally polarized light is preferentially oscillated, the vertically polarized light is suppressed, and the horizontal linearly polarized laser output is obtained, thereby improving the coherence of the laser, weakening the interference of the vertical polarization on the laser output, and finally making the amplitude of the microwave harmonic signal more stable.

Claims (4)

1. a kind of microwave harmonic wave generation device based on Optical phase-locked loop, it is characterised in that the microwave harmonic wave generation device includes laser Source generator and laser coupled mirror, it is defeated by tunable multi-longitudinal mode solid laser, fibre-coupled mirrors, optical fiber dense wavelength division multiplex device Enter end and its two adjacent output optical fibres, optical-fiber bundling device, optical-electrical converter, the microwave mixer with microwave signal input port, The Optical phase-locked loop that low-frequency amplifier, loop filter are in series, and by optical fiber dense wavelength division multiplex device output optical fibre its Two frequencys multiplication or multiple frequence harmonic wave of the microwave signal that remaining any two output optical fibre is in series with optical-fiber bundling device, optical-electrical converter Output port；Laser generator sends during work laser Jing laser coupled mirrors be input into tunable multi-longitudinal mode solid laser and Microwave signal is then input into by the microwave signal input port of microwave mixer.

2. the microwave harmonic wave generation device of Optical phase-locked loop is based on as described in claim 1, it is characterised in that the lasing light emitter occurs Device is semiconductor pump laser.

3. the microwave harmonic wave generation device as described in claim 1 based on Optical phase-locked loop, it is characterised in that described tunable to indulge more Mould solid state laser is the resonator being made up of forward and backward hysteroscope, the working-laser material being placed in resonator, is close to laser work Make the piezoelectric ceramics and its piezoelectric actuator on material, and many longitudinal mode solids of tunable short cavity of semiconductor refrigeration sheet composition swash Light device.

4. the microwave harmonic wave generation device of Optical phase-locked loop is based on as described in claim 1 or 3, it is characterised in that the laser work For inclined plane, front cavity mirror is then corresponding tiltler to the front end face of material；Working-laser material front end face and semiconductor refrigerating The inclination angle theta of piece upper surface₁The inclination angle theta of front cavity mirror and semiconductor chilling plate upper surface for 50 °～65 °₂For 50 °～80 °.