阅读说明：本技术 一种基于激光器相控阵列的线性啁啾微波信号产生装置 (Linear chirp microwave signal generating device based on laser phased array ) 是由 李念强 张仁恒 周沛 于 2020-07-15 设计创作，主要内容包括：本发明属于微波光子技术领域,为解决现有微波信号产生装置输出功率不高的问题公开了一种基于激光器相控阵列的线性啁啾微波信号产生装置,包括：外部光源激光器、光衰减器、第一偏振控制器、强度调制器、波形发生器、第二偏振控制器、光环行器、激光器相控阵列和光电二极管。激光器相控阵列由多个节点激光器集成,外部光信号只注入到激光器相控阵列中的一个节点激光器,在适当的注入功率下,激发激光器相控阵列的单周期振荡输出,激光器相控阵列中的所有节点激光器间采用负折射率引导和增益引导的波导结构,使得具有相同的振荡频率和相位,实现了输出功率增强；具有高度集成性、高功率化及产生多路并行的同频同相线性啁啾微波信号的优点。(The invention belongs to the technical field of microwave photon, and discloses a linear chirp microwave signal generating device based on a laser phased array, which aims to solve the problem that the output power of the existing microwave signal generating device is not high, and comprises: the device comprises an external light source laser, an optical attenuator, a first polarization controller, an intensity modulator, a waveform generator, a second polarization controller, an optical circulator, a laser phased array and a photodiode. The laser phased array is integrated by a plurality of node lasers, external optical signals are only injected into one node laser in the laser phased array, single-period oscillation output of the laser phased array is excited under proper injection power, and a waveguide structure with negative refractive index guide and gain guide is adopted among all the node lasers in the laser phased array, so that the laser phased array has the same oscillation frequency and phase, and output power enhancement is realized; the method has the advantages of high integration, high power and capability of generating multi-path parallel same-frequency same-phase linear chirp microwave signals.)

1. A linearly chirped microwave signal generation apparatus based on a laser phased array, characterized by comprising: external light source laser (1), optical attenuator (2), first polarization controller (3), intensity modulator (4), waveform generator (5), second polarization controller (6), optical circulator (7), laser phased array (8) and photodiode (9), wherein: the laser phased array is formed by packaging and integrating a plurality of node lasers, and the external light source laser (1), the optical attenuator (2), the first polarization controller (3), the intensity modulator (4) and the second polarization controller (6) are sequentially connected through optical fibers; the output end of the waveform generator (5) is connected with the radio frequency end of the intensity modulator (6) through a radio frequency line; the output end of the second polarization controller (6) is connected to a first port of the optical circulator (7); the output end of the laser phased array (8) is connected to the second port of the optical circulator (7); the third port of the optical circulator (7) is connected with a photodiode (9); a linearly chirped microwave signal is derived from the output of the photodiode (9).

2. The apparatus for generating a linearly chirped microwave signal according to claim 1, wherein the pitch between the laser nodes in the laser phased array is 1 μm to 100 μm.

3. The laser phased array based linearly chirped microwave signal generation apparatus according to claim 1, characterized in that: the emission frequency of the external light source laser (1) is greater than the total electric field free resonance frequency of the laser phased array (8); the external light source laser (1) is injected into only one node laser in the laser phased array (8), the other node lasers in the laser phased array (8) and the injected node lasers keep the same frequency offset, and the frequency offset is equal to the detuning frequency.

4. The linear chirped microwave signal generation device based on the laser phased array according to claim 1, characterized in that the external light source laser (1) is injected into one node laser in the laser phased array (8), the node laser presents a single period oscillation state, all the other node lasers in the laser phased array (8) are excited to the single period oscillation state, the oscillation frequency and the phase of all the node lasers in the laser phased array (8) are the same, and the total output power of the laser phased array is the sum of the light intensity of all the node lasers.

5. The laser phased array based linearly chirped microwave signal generation apparatus according to claim 1,

is characterized in that a sawtooth-like waveform generated by a waveform generator (6) is input to an intensity modulator (5) to modulate the intensity of an optical signal output by an external light source laser, and the optical signal output by a laser phased array (8) is subjected to photoelectric conversion by a photodiode (9) to generate a linear chirped microwave signal.

Technical Field

The invention relates to the field of microwave photon technology and radar, in particular to a linear chirp microwave signal generation device based on a light injection laser phased array.

Background

Semiconductor lasers are devices that use semiconductor materials as working substances to achieve laser output. It has small volume and long service life, and is pumped by simple current injection, and its working voltage and current are compatible with integrated circuit, so that it can be monolithically integrated with it. Because of these advantages, semiconductor lasers have been widely used in laser communication, optical storage, optical gyro, laser printing, ranging, radar, and the like. The linear chirp waveform is the most commonly used transmitted signal waveform of the radar, and the detection distance and the detection precision of the radar can be improved by a pulse compression technology. In recent years, with the development of photonics technology, researchers have begun to replace conventional electronic devices with photonic devices such as semiconductor lasers to generate linearly chirped microwave signals, thereby solving the limitations of electronic devices in terms of center frequency and bandwidth. For example: a swept-frequency optoelectronic oscillator-based linear chirped microwave signal Generation scheme (see [ p. Zhou, f. Zhang, and s. Pan, "Generation of linear-modulated wave forms by a frequency-sweeping optoelectronic oscillator," Journal of Lightwave Technology 36(18), ] 3927-3934 (2018) ]; a generation scheme based on dual-polarization parallel Mach-Zehnder modulators (see [ P. Li, L. Yan, J. Ye, X. Zou, B.Luo, and W. Pan, "Photonic apparatus for the generation of switchable down-, up-, and dual-chip linear frequency-modulated microwave signals," optics letters 45(7), 1990) 1993 (2020) ]. These schemes all use semiconductor lasers to produce linearly chirped microwave signals. In general, the higher the temperature of the semiconductor laser, the longer the wavelength, but this also leads to a reduction in the emission intensity.

Therefore, the driving current of most semiconductor lasers is limited to about 20 mA, and the output power thereof is about several tens mW. With the higher and higher requirements of modern communication on the output power of the laser, the single semiconductor laser can not meet the requirements of the output power. Through the waveguide coupling technology, a plurality of lasers are integrated together to form a linear array or an area array, and the optical power output of several kW can be achieved.

Disclosure of Invention

The invention mainly aims to provide a linear chirped microwave signal generation device and method based on a laser phased array, so as to solve the defects of the existing common method, namely (1) the output power of a single semiconductor laser is not high, and (2) the system size of a discrete laser is overlarge and the energy consumption is overlarge. Based on the advantages of the phased array, the device also has the characteristic of realizing multi-path parallel same-frequency and same-phase signal output.

The invention provides a linear chirp microwave signal generating device based on a laser phased array, which comprises: the device comprises an external light source laser, an optical attenuator, a first polarization controller, an intensity modulator, a waveform generator, a second polarization controller, an optical circulator, a laser phased array and a photodiode; wherein: the laser phased array is packaged and integrated by a plurality of node lasers under specific planar waveguide coupling, and the external light source laser, the optical attenuator, the first polarization controller, the intensity modulator and the second polarization controller are sequentially connected through optical fibers; the output end of the waveform generator is connected to the radio frequency end of the intensity modulator through a radio frequency line; the output end of the second polarization controller is connected to the first port of the optical circulator; the output end of the laser phased array is connected to the second port of the optical circulator; the third port of the optical circulator is connected with the photodiode; the linearly chirped microwave signal is derived from the output of the photodiode.

The node lasers in the array are connected together in an evanescent field coupling mode, and the evanescent field coupling is realized by periodically changing the real part of the refractive index, so that the peak value of each unit optical field is distributed in a low-refractive-index area when the array runs. Therefore, the output light beams of each light-emitting unit can have coherence, namely phase locking is realized, so that coherent light output can be obtained, the quality of the light beams is improved, and the output coherent energy is concentrated and increased. A laser phased array is an integrated device grown and packaged together with multiple node lasers coupled by a particular planar waveguide structure. External optical signals are injected into only one node laser in the laser phased array, single-period oscillation output of the laser phased array is excited under appropriate injection power, and a waveguide structure with negative refractive index guiding and gain guiding is adopted among all the node lasers in the laser phased array, so that the node lasers have the same oscillation frequency and phase, and therefore output power increase can be achieved. The intensity of the injected light signal is modulated, and a linear chirp microwave signal can be obtained after photoelectric conversion. By means of external coupling selection output, simultaneous generation of multiple linear chirp signals can be achieved.

The further scheme is as follows: the pitch of the node lasers is 1-100 μm.

The more preferable scheme is as follows: the emission frequency of the external light source laser is greater than the total electric field free resonance frequency of the laser phased array, namely positive frequency detuning; the external light source laser only injects into a node laser in the laser phased array, the other node lasers in the laser phased array and the injected node laser keep the same frequency bias, and the frequency bias is equal to the detuning frequency.

The more preferable scheme is as follows: the external light source laser is injected into one node laser in the laser phased array, the node laser presents a single-period oscillation state, all the other node lasers in the laser phased array are excited to be in the single-period oscillation state, and the oscillation frequency and the phase of all the node lasers in the laser phased array are the same.

The more preferable scheme is as follows: the sawtooth-like waveform generated by the waveform generator is input to the intensity modulator to modulate the intensity of the optical signal output by the external light source laser, and the optical signal output by the laser phased array is subjected to photoelectric conversion by the photodiode to generate a linear chirp microwave signal.

Compared with the prior art, the linear chirped microwave signal generation device based on the laser phased array has the following advantages:

1. the device has high integration. The laser phased array is formed by packaging and integrating a plurality of lasers under specific planar waveguide coupling, the pitch of each laser node is 1-100 mu m, and the size of each laser node is far smaller than that of a current discrete laser device.

2. The device has high power and multipath parallelism. The same-frequency and same-phase oscillation behavior of all the node lasers in the array can be realized only by injecting one node laser into the laser phased array, the output power of the laser phased array is far higher than that of a single semiconductor laser, and multiple paths of parallel same-frequency and same-phase linear chirp microwave signals can be generated.

The drawings illustrate the following:

FIG. 1 is a schematic diagram of a linear chirped microwave signal generation device based on a laser phased array provided by the present invention;

FIG. 2 is a spectrum of the output of node laser a;

FIG. 3 is a spectrum of the output of node laser b;

FIG. 4 is a graph of the spectrum of an output single frequency microwave signal;

fig. 5 is a time domain waveform diagram of an output linearly chirped microwave signal;

fig. 6 is a time-frequency diagram of an output linearly chirped microwave signal;

wherein: 1-external light source laser, 2-optical attenuator, 3-first polarization controller, 4-intensity modulator, 5-waveform generator, 6-second polarization controller, 7-optical circulator, 8-laser phased array, and 9-photodiode.

Detailed Description

Referring to fig. 1, a system block diagram of a linear chirped microwave signal generation device based on a laser phased array is shown. The device can generate linear chirp microwave waveforms, the bandwidth of the linear chirp microwave waveforms reaches 3 GHz, and the time width reaches 1 mu s.

In fig. 1, the method includes: an external light source laser 1, an optical attenuator 2, a first polarization controller 3, an intensity modulator 4, a waveform generator 5, a second polarization controller 6, an optical circulator 7, a laser phased array 8, and a photodiode 9, wherein: the laser phased array 8 is formed by packaging and integrating a plurality of node lasers, and the external light source laser, the optical attenuator 2, the first polarization controller 3, the intensity modulator 4 and the second polarization controller 6 are sequentially connected through optical fibers; the output end of the waveform generator 5 is connected to the radio frequency end of the intensity modulator through a radio frequency line; the output end of the second polarization controller 6 is connected to the first port of the optical circulator 7; the output end of the laser phased array 8 is connected to the second port of the optical circulator 7; the third port of the optical circulator 7 is connected with a photodiode 9; the linearly chirped microwave signal is derived from the output of the photodiode 9.

Fig. 1 is a schematic diagram showing the connection relationship between the technical features of the device according to the present embodiment, and the shape of each component in fig. 1 is only illustrative and is not limited to the shape and structure.

The invention relates to a linear chirped microwave signal generation device based on a laser phased array, which comprises the following specific working processes:

the present invention excites the one-period oscillation nonlinear dynamics state of the laser phased array 8 based mainly on external light injection into the light injection structure of the laser phased array. The emitting frequency of the external light source laser is set to be larger than the total electric field free resonance frequency of the laser phased array 8, namely, positive frequency detuning is achieved, the external light source laser is only injected into one node laser in the laser phased array 8, the other node lasers in the laser phased array 8 and the injected node lasers keep the same frequency offset, and the frequency offset is equal to the detuning frequency. The intensity of the injected light signal is controlled by adjusting the optical attenuator 2, all node lasers in the laser phased array 8 realize single-period oscillation nonlinear dynamics output within a proper injection power range, the oscillation frequencies are the same, and single-frequency microwave signals are generated after photoelectric conversion is completed by the photodiode 9. On the basis of this, the waveform generator 5 outputs a sawtooth-like waveform signal, which is modulated on the intensity modulator 4 to intensity-modulate the output light of the external light source laser 1. The single-frequency microwave signal output by the photodiode 9 is converted into a linearly chirped microwave signal. The frequency range of the generated linear chirp microwave signal can be changed by adjusting the frequency emitted by an external light source laser; the bandwidth of the generated linear chirp microwave signal can be changed by adjusting the amplitude of the waveform output by the waveform generator 5; the time period of the generated linearly chirped microwave signal can be varied by adjusting the time period of the waveform output by the waveform generator 5.

The effect of the device of the present invention for generating a linear chirped microwave signal will be described by taking a laser phased array 8 formed by packaging two node lasers as an example:

two node lasers in laser phased array 8 are node laser a and node laser b respectively, and the light signal of external light source laser transmission only injects into node laser a, and node laser b does not receive the injection. The transmitting frequency of the node laser a is 230.6096 THz, the transmitting frequency of the external light source laser is 15 GHz higher than that of the node laser a, namely, the frequency detuning between the external light source laser and the node laser a is 15 GHz, the transmitting frequency of the node laser b is 15 GHz higher than that of the node laser a, namely, the frequency offset between the node laser b and the node laser a is 15 GHz. At a suitable injection power, the laser phased array 8 operates in a single-period oscillation state. FIG. 2 is a spectrum of node laser a; fig. 3 is a spectrum diagram of the node laser b. It can be seen that the node laser a and the node laser b oscillate at the same frequency. After photoelectric conversion is completed by the photodiode 9, a single-frequency microwave signal is generated. Fig. 4 is a spectrum diagram of a single frequency microwave signal. The waveform generator 5 outputs a sawtooth-like waveform signal with a frequency of 1 MHz, and the single-frequency microwave signal output by the photodiode 9 is converted into a linear chirp microwave signal. FIG. 5 is a time domain waveform diagram of a linearly chirped microwave signal; fig. 6 is a time-frequency diagram of a linearly chirped microwave signal. It can be seen that the frequency of the linearly chirped microwave signal increases linearly with time over a period of 1 mus. Therefore, the linear chirp microwave signal can be obtained by adopting the technical scheme. Therefore, the method has the advantages of high integration, high power and the generation of multi-path parallel same-frequency same-phase linear chirp microwave signals.

The above description is only for the preferred embodiment of the present invention and should not be taken as limiting the invention, and it should be understood that any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.