CN103337776A - All-optical fiber type self-mixing distance measuring system of laser - Google Patents

All-optical fiber type self-mixing distance measuring system of laser Download PDF

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CN103337776A
CN103337776A CN201310232184XA CN201310232184A CN103337776A CN 103337776 A CN103337776 A CN 103337776A CN 201310232184X A CN201310232184X A CN 201310232184XA CN 201310232184 A CN201310232184 A CN 201310232184A CN 103337776 A CN103337776 A CN 103337776A
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optical fiber
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CN103337776B (en
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吕亮
俞本立
朱军
张道信
赵云鹤
杜正婷
杨波
张文华
黄欢
徐浩
周林
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Anhui University
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Abstract

本发明公开了一种全光纤型激光自混合测距系统,其特征是以可调谐激光器通过光收集与耦合系统的输出端向被测物体出射初始波长为λ、调谐频率为νm、调谐幅度为Δλ的激光信号,并通过光收集与耦合系统的输出端接收来自被测物体的散射面的反馈光信号形成激光自混合信号;光电信号转换单元接受激光自混合信号并转换为电信号;信号处理单元利用激光自混合信号的波动频率ΔνL获得被测物体的散射面与可调谐光纤激光器的输出端面之间的距离。本发明测量精度高、工作性能稳定,应用场合广泛,特别是远距离测量。

The invention discloses an all-fiber laser self-mixing ranging system, which is characterized in that a tunable laser emits light to a measured object through the output end of the light collection and coupling system. The initial wavelength is λ, the tuning frequency is ν m , and the tuning amplitude is The laser signal is Δλ, and receives the feedback optical signal from the scattering surface of the measured object through the output end of the light collection and coupling system to form a laser self-mixing signal; the photoelectric signal conversion unit receives the laser self-mixing signal and converts it into an electrical signal; the signal The processing unit uses the fluctuation frequency Δν L of the laser self-mixing signal to obtain the distance between the scattering surface of the measured object and the output end surface of the tunable fiber laser. The invention has high measurement precision, stable working performance and wide application occasions, especially long-distance measurement.

Description

一种全光纤型激光自混合测距系统An all-fiber laser self-mixing ranging system

技术领域technical field

本发明涉及目标物绝对距离的光学检测系统,特别涉及一种自混合激光测距系统。The invention relates to an optical detection system for the absolute distance of a target object, in particular to a self-mixing laser ranging system.

背景技术Background technique

目标物绝对距离的光学检测可广泛应用于矿井采掘、电力、水利、通讯、环境、建筑、农业、林业等诸多领域。现有技术中,基于脉冲激光的飞行时间测距方法相对精度较低,灵敏度较低;外差型相位式激光测距仪系统包括有参考臂和测量臂,结构相对较为复杂;基于注入电流调谐的半导体激光自混合测距技术具有结构紧凑、重量轻、体积小、可靠性高、适合现场测量等优点,逐渐得到广泛应用。The optical detection of the absolute distance of the target can be widely used in mining, electric power, water conservancy, communication, environment, construction, agriculture, forestry and many other fields. In the prior art, the time-of-flight ranging method based on pulsed laser has relatively low precision and low sensitivity; the heterodyne phase laser rangefinder system includes a reference arm and a measuring arm, and the structure is relatively complicated; tuning based on injection current The semiconductor laser self-mixing ranging technology has the advantages of compact structure, light weight, small size, high reliability, suitable for on-site measurement, etc., and has gradually been widely used.

激光自混合测距原理如图4所示,干涉系统由可调谐激光器和外部反射物体组成。反馈光存在的时候可以通过改变激光器腔内的载流子密度造成激光介质折射率发生变化进而调制激光器本身的频率和强度,形成自混合干涉。The principle of laser self-mixing ranging is shown in Figure 4. The interference system consists of a tunable laser and an external reflective object. When the feedback light exists, the frequency and intensity of the laser itself can be modulated by changing the carrier density in the laser cavity to cause a change in the refractive index of the laser medium, forming self-mixing interference.

令激光器前端面17与激光器后端面18之间的长度为L0,前端面和后端面的反射系数分别为r1和r2,前端面到目标物体散射端面19之间的外腔长度为Lext,外腔反射系数为r3,激光介质的折射率为n,初始的光场为E0,自混合干涉后的光场为E(t),则有:Let the length between the front end face 17 of the laser and the rear end face 18 of the laser be L0 , the reflection coefficients of the front end face and the rear end face be r1 and r2 respectively, and the length of the external cavity between the front end face and the scattering end face 19 of the target object be L ext , the reflection coefficient of the external cavity is r 3 , the refractive index of the laser medium is n, the initial light field is E 0 , and the light field after self-mixing interference is E(t), then:

E ( t ) = r 1 r 2 exp { - j 4 πv nL 0 c + ( g - γ ) L 0 } E 0 +    (2) E. ( t ) = r 1 r 2 exp { - j 4 πv nL 0 c + ( g - γ ) L 0 } E. 0 + (2)

rr 11 (( 11 -- rr 22 22 )) expexp {{ -- jj 44 πvπv nLnL 00 ++ LL extext cc ++ (( gg -- γγ )) LL 00 }} EE. 00

式(2)中g为激光腔内单位长度引起的线性增益,γ为激光腔内单位长度的损耗,ν为激光的振荡频率。由于激光器阈值增益被反馈光调制,激光输出功率比例于激光阈值增益,因此,激光的输出功率被反馈光调制,输出的光功率如式(3)所表达:In formula (2), g is the linear gain caused by unit length in the laser cavity, γ is the loss per unit length in the laser cavity, and ν is the oscillation frequency of the laser. Since the threshold gain of the laser is modulated by the feedback light, the laser output power is proportional to the laser threshold gain. Therefore, the output power of the laser is modulated by the feedback light, and the output optical power is expressed as formula (3):

I=I0[1+mcos(2πντL)]   (3)I=I 0 [1+mcos(2πντ L )] (3)

式(3)中,调制系数m在工作电流一定时为比例于反馈强度的常数。

Figure BDA00003333907800013
为激光在内外腔传播一周的延迟时间,I0为激光器没有外腔反馈时的激光强度。In formula (3), the modulation coefficient m is a constant proportional to the feedback strength when the working current is constant.
Figure BDA00003333907800013
I 0 is the laser intensity when the laser has no feedback from the external cavity.

在式(3)中,激光器的输出强度与激光器外腔长度的变化相关及反馈物的位移相关,假设所加调制引起激光器光频波动为:In formula (3), the output intensity of the laser is related to the change of the length of the external cavity of the laser and the displacement of the feedback object. It is assumed that the optical frequency fluctuation of the laser caused by the added modulation is:

I(t)=I0+ΔI(t)   (4)I(t)=I 0 +ΔI(t) (4)

ν(t)=ν0+Δν(t)   (5)ν(t)=ν 0 +Δν(t) (5)

式(4)和式(5)中,I0,ν0代表无反馈和无调制下的激光器光强和光波频率,I(t),ν(t)分别代表激光器在调制下输出激光光强和光波频率,激光强度和光波频率可由光功率计和频谱仪测定。Δν(t)为频率在调谐单元作用下随时间变化量,定义其变化幅度为Δν。其中ΔI(t),Δν(t)由激光器的调制特性决定。In formula (4) and formula (5), I 0 , ν 0 represent the light intensity and light frequency of the laser without feedback and without modulation, and I(t), ν(t) represent the output laser light intensity of the laser under modulation respectively And light wave frequency, laser intensity and light wave frequency can be measured by optical power meter and spectrum analyzer. Δν(t) is the amount of frequency change with time under the action of the tuning unit, and its variation range is defined as Δν. Among them, ΔI(t) and Δν(t) are determined by the modulation characteristics of the laser.

I(t)=[I0+ΔI(t)]{1+mcos[2πν(t)τL]}   (6)I(t)=[I 0 +ΔI(t)]{1+mcos[2πν(t)τ L ]} (6)

因此目标物散射面与激光器出射端面的距离为式(1)所示:

Figure BDA00003333907800021
Therefore, the distance between the scattering surface of the target object and the exit end surface of the laser is shown in formula (1):
Figure BDA00003333907800021

由式(1)可知目标物散射面与激光器出射端面的距离和自混合信号的波动频率ΔνL成线性关系,且激光器测量精度主要受调谐范围Δλ影响。It can be seen from formula (1) that the distance between the scattering surface of the target and the laser output end face is linearly related to the fluctuation frequency Δν L of the self-mixing signal, and the measurement accuracy of the laser is mainly affected by the tuning range Δλ.

这种通过注入电流调谐半导体激光器的输出波长,进而实现测距目的主要存在以下问题:This kind of tuning the output wavelength of the semiconductor laser by injecting current to achieve the purpose of distance measurement mainly has the following problems:

1、由于半导体激光器注入电流的幅度受限于半导体的注入电流工作范围,从而限制了其输出波长的调谐范围,典型的电流注入型F-P型半导体激光器的调谐范围一般在10nm左右。根据测距原理,调谐范围Δλ较小,造成测量精度下降,无法实现高精度测距;1. Since the amplitude of the injection current of the semiconductor laser is limited by the working range of the injection current of the semiconductor, the tuning range of its output wavelength is limited. The tuning range of a typical current injection type F-P semiconductor laser is generally around 10nm. According to the principle of ranging, the tuning range Δλ is small, resulting in a decrease in measurement accuracy, and it is impossible to achieve high-precision ranging;

2、电流注入型半导体激光器进行调谐时,激光器工作性能不稳定,输出功率波动严重,造成输出自混合信号不稳定,影响测距效果;2. When the current injection type semiconductor laser is tuned, the working performance of the laser is unstable, and the output power fluctuates seriously, resulting in unstable output self-mixing signal and affecting the ranging effect;

3、半导体激光器典型线宽范围为2nm,一般为多纵模工作,导致激光光束的单色性和相干性差,影响了其传输和传感特性,并且远距离工作时发散角较大,直接限制激光自混合测距技术的应用场合和工作距离。3. The typical line width range of semiconductor lasers is 2nm, and they generally work in multiple longitudinal modes, resulting in poor monochromaticity and coherence of the laser beam, which affects its transmission and sensing characteristics, and the divergence angle is large when working at a long distance, which directly limits Applications and working distances of laser self-mixing ranging technology.

发明内容Contents of the invention

本发明是为避免上述现有技术所存在的不足,提供一种测量精度更高、工作性能更加稳定,应用场合广泛,特别是远距离测量的全光纤型激光自混合测距系统。The purpose of the present invention is to avoid the shortcomings of the above-mentioned prior art and provide an all-fiber laser self-mixing distance measuring system with higher measurement accuracy, more stable working performance and wide application occasions, especially long-distance measurement.

本发明为解决技术问题采用如下技术方案:The present invention adopts following technical scheme for solving technical problems:

本发明全光纤型激光自混合测距系统的特点是:采用一可调谐光纤激光器,与所述可调谐光纤激光器配合设置有具有光电探测器的光电信号转换单元、信号处理单元和位于所述可调谐光纤激光器的前端的光收集与耦合系统;所述可调谐激光器通过光收集与耦合系统的输出端向被测物体出射初始波长为λ、调谐频率为νm、调谐幅度为Δλ的激光信号,并通过光收集与耦合系统的输出端接收来自被测物体的散射面的反馈光信号形成激光自混合信号;所述光电信号转换单元是以光电探测器接受在所述可调谐激光器中形成的激光自混合信号并转换为电信号;所述信号处理单元接收并处理来自所述光电信号转换单元的电信号,利用激光自混合信号的波动频率ΔνL,由式(1)获得被测物体的散射面与可调谐光纤激光器的输出端面之间的距离LextThe feature of the all-fiber laser self-mixing ranging system of the present invention is that a tunable fiber laser is used, and a photoelectric signal conversion unit with a photodetector, a signal processing unit and a signal processing unit located in the tunable fiber laser are arranged in cooperation with the tunable fiber laser. The light collection and coupling system at the front end of the tunable fiber laser; the tunable laser emits a laser signal with an initial wavelength of λ, a tuning frequency of ν m and a tuning amplitude of Δλ to the measured object through the output end of the light collection and coupling system, And through the output end of the light collection and coupling system, the feedback optical signal from the scattering surface of the measured object is received to form a laser self-mixing signal; the photoelectric signal conversion unit uses a photodetector to receive the laser light formed in the tunable laser The self-mixing signal is converted into an electrical signal; the signal processing unit receives and processes the electrical signal from the photoelectric signal conversion unit, and uses the fluctuation frequency Δν L of the laser self-mixing signal to obtain the scattering of the measured object by formula (1) The distance L ext between the face and the output end face of the tunable fiber laser:

LL extext == ΔvΔv LL λλ 22 44 vv mm ΔλΔλ -- -- -- (( 11 )) ..

本发明全光纤型激光自混合测距系统的结构特点也在于:The structural features of the all-fiber laser self-mixing ranging system of the present invention also lie in:

设置所述可调谐光纤激光器的结构形式为:采用线形腔结构的谐振腔体,所述谐振腔体由设置在可调谐光纤激光器的前端面位置处的窄带反射镜和后端面位置处的宽带反射镜组成;由波分复用器件将泵浦单元输出的泵浦光接入谐振腔体,以所述泵浦光激发谐振腔体内的有源增益介质在所述谐振腔体内产生激光;所述波分复用器件的输出端连接耦合器的输入端;以所述耦合器的第一输出端连接所述光收集与耦合系统,以所述耦合器的第二输出端连接所述光电信号转换单元;设置调谐单元为调谐功能器件,通过所述调谐单元的调谐作用使所述可调谐光纤激光器从所述耦合器的第一输出端输出调谐频率为νm、调谐幅度为Δλ的激光信号。The structural form of setting the tunable fiber laser is: a resonant cavity with a linear cavity structure, and the resonant cavity is composed of a narrow-band reflector at the front end of the tunable fiber laser and a broadband reflector at the rear end. Composed of mirrors; the pump light output by the pump unit is connected to the resonant cavity by a wavelength division multiplexing device, and the active gain medium in the resonant cavity is excited by the pump light to generate laser light in the resonant cavity; The output end of the wavelength division multiplexing device is connected to the input end of the coupler; the first output end of the coupler is connected to the optical collection and coupling system, and the second output end of the coupler is connected to the photoelectric signal conversion A unit; the tuning unit is set as a tuning function device, and the tuning function of the tuning unit enables the tunable fiber laser to output a laser signal with a tuning frequency of ν m and a tuning amplitude of Δλ from the first output end of the coupler.

所述宽带反射镜设置为光纤环镜反射镜或介质膜光纤反射镜,所述窄带反射镜设置为具有选频功能的光纤光栅。The broadband reflector is set as a fiber loop reflector or a dielectric film fiber reflector, and the narrowband reflector is set as a fiber grating with a frequency selection function.

本发明全光纤型激光自混合测距系统的结构特点还在于:The structural characteristics of the all-fiber laser self-mixing ranging system of the present invention are also:

设置所述可调谐光纤激光器的结构形式为:采用环形腔结构的谐振腔体,由波分复用器件将泵浦单元输出的泵浦光接入环形腔结构的谐振腔体中,以所述泵浦光激发谐振腔体内的有源增益介质,并经过窄带反射镜在所述谐振腔体内产生激光;耦合器的输入端与所述环形腔结构的谐振腔体连接,耦合器的第一输出端连接窄带反射镜,调谐单元连接所述光收集与耦合系统,耦合器的第二输出端连接所述光电信号转换单元;设置调谐单元为调谐功能器件,通过所述调谐单元的调谐作用使所述可调谐光纤激光器从所述窄带反射镜输出端输出调谐频率为νm、调谐幅度为Δλ的激光信号。The structural form of the tunable fiber laser is set as follows: a resonant cavity with a ring cavity structure is used, and the pump light output by the pump unit is connected to the resonant cavity with a ring cavity structure by a wavelength division multiplexing device. The pump light excites the active gain medium in the resonant cavity, and generates laser light in the resonant cavity through a narrow-band mirror; the input end of the coupler is connected with the resonant cavity of the ring cavity structure, and the first output of the coupler The end is connected to the narrow-band reflector, the tuning unit is connected to the optical collection and coupling system, and the second output end of the coupler is connected to the photoelectric signal conversion unit; the tuning unit is set as a tuning function device, and the tuning function of the tuning unit makes all The tunable fiber laser outputs a laser signal with a tuning frequency of ν m and a tuning amplitude of Δλ from the output end of the narrow-band mirror.

所述窄带反射镜设置为具有选频功能的光纤光栅,在有源光纤和耦合器之间加入一隔离器,由所述隔离器隔离反馈光控制激光在所述谐振腔体中的单向传输。The narrow-band reflector is set as a fiber grating with a frequency selection function, and an isolator is added between the active fiber and the coupler, and the feedback light is isolated by the isolator to control the unidirectional transmission of the laser in the resonant cavity .

所述光收集与耦合系统设置为透镜或透镜组,用于调节所述可调谐光纤激光器的出射光强和来自所述被测物体的反馈光信号光强。The light collection and coupling system is configured as a lens or a lens group, which is used to adjust the outgoing light intensity of the tunable fiber laser and the light intensity of the feedback optical signal from the measured object.

与已有技术相比,本发明有益效果体现在:Compared with the prior art, the beneficial effects of the present invention are reflected in:

1、本发明所采用可调谐光纤激光器的调谐波长的移动范围可达100nm甚至更高,相对注入电流调谐的半导体激光器具有更大的调谐范围。因此本发明系统精度相对更高。1. The moving range of the tuning wavelength of the tunable fiber laser used in the present invention can reach 100nm or even higher, which has a larger tuning range than the semiconductor laser tuned by injection current. Therefore, the accuracy of the system of the present invention is relatively higher.

2、光纤激光器宽带调谐特性可保证光纤激光器调谐过程宽带平坦的高增益特性且输出功率稳定,因此可保证本发明全光纤型激光自混合测距系统的稳定性和测距效果。2. The broadband tuning characteristics of the fiber laser can ensure the high-gain characteristics of the fiber laser tuning process with flat broadband and stable output power, so the stability and ranging effect of the all-fiber laser self-mixing ranging system of the present invention can be guaranteed.

3、本发明所采用的光纤激光器输出激光线宽可达到0.02nm,相对于半导体激光器,为单纵模或少纵模输出,良好的相干特性、模式特性以及较小的光束发散角可充分应用于远距离传感测量,并且全光纤结构耦合方式简单、结构紧凑,可满足特殊距离测量场合的应用需求。3. The output laser linewidth of the fiber laser used in the present invention can reach 0.02nm. Compared with semiconductor lasers, it is a single longitudinal mode or few longitudinal mode output, and its good coherence characteristics, mode characteristics and small beam divergence angle can be fully applied It is suitable for long-distance sensing and measurement, and the coupling method of the all-fiber structure is simple and the structure is compact, which can meet the application requirements of special distance measurement occasions.

附图说明Description of drawings

图1为本发明结构示意图;Fig. 1 is a structural representation of the present invention;

图2为本发明中线形腔结构可调谐光纤激光器结构示意图;Fig. 2 is a schematic structural diagram of a tunable fiber laser with a linear cavity structure in the present invention;

图3为本发明中环形腔结构可调谐光纤激光器结构示意图;Fig. 3 is a structural schematic diagram of a tunable fiber laser with a ring cavity structure in the present invention;

图4为自混合干涉系统示意图;Fig. 4 is the schematic diagram of self-mixing interference system;

图中标号:1可调谐光纤激光器、2光电信号转换单元、3信号处理单元、4光收集与耦合系统、5被测物体、6泵浦单元、7调谐单元、8宽带反射镜、9窄带反射镜、10波分复用器件、11有源增益介质、12耦合器;13第一输出端;14第二输出端、15隔离器、16激光器输出端口、17激光器前端面、18激光器后端面、19目标物体散射端面。Labels in the figure: 1 tunable fiber laser, 2 photoelectric signal conversion unit, 3 signal processing unit, 4 optical collection and coupling system, 5 measured object, 6 pump unit, 7 tuning unit, 8 broadband reflector, 9 narrowband reflection mirror, 10 wavelength division multiplexing device, 11 active gain medium, 12 coupler; 13 first output end; 14 second output end, 15 isolator, 16 laser output port, 17 laser front face, 18 laser rear face, 19 target object scattering end face.

具体实施方式Detailed ways

参见图1,本实施例中全光纤型激光自混合测距系统是采用一可调谐光纤激光器1,与可调谐光纤激光器1配合设置有具有光电探测器的光电信号转换单元2、信号处理单元3和位于可调谐光纤激光器1的前端的光收集与耦合系统4;可调谐激光器1通过光收集与耦合系统4的输出端向被测物体5出射初始波长为λ、调谐频率为νm、调谐幅度为Δλ的激光信号,并通过光收集与耦合系统4的输出端接收来自被测物体5的散射面的反馈光信号形成激光自混合信号;光电信号转换单元2是以光电探测器接受在可调谐激光器1中形成的激光自混合信号并转换为电信号;信号处理单元3接收并处理来自光电信号转换单元2的电信号,利用激光自混合信号的波动频率ΔνL,由式(1)获得被测物体5的散射面与可调谐光纤激光器1的输出端面之间的距离LextReferring to Fig. 1, the all-fiber laser self-mixing ranging system in this embodiment adopts a tunable fiber laser 1, and is equipped with a photoelectric signal conversion unit 2 and a signal processing unit 3 with a photodetector in cooperation with the tunable fiber laser 1 and the light collection and coupling system 4 located at the front end of the tunable fiber laser 1; the tunable laser 1 emits light to the measured object 5 through the output end of the light collection and coupling system 4. The initial wavelength is λ, the tuning frequency is ν m , and the tuning amplitude is The laser signal is Δλ, and receives the feedback optical signal from the scattering surface of the measured object 5 through the output end of the light collection and coupling system 4 to form a laser self-mixing signal; The laser self-mixing signal formed in the laser 1 is converted into an electrical signal; the signal processing unit 3 receives and processes the electrical signal from the photoelectric signal conversion unit 2, using the fluctuation frequency Δν L of the laser self-mixing signal, obtained by formula (1) The distance L ext between the scattering surface of the measuring object 5 and the output end face of the tunable fiber laser 1:

LL extext == ΔvΔv LL λλ 22 44 vv mm ΔλΔλ -- -- -- (( 11 ))

具体实施中,信号处理单元3常规设置有放大、滤波和解调部分;光收集与耦合系统4设置为透镜或透镜组,用于调节可调谐光纤激光器1的出射光强和来自被测物体5的反馈光信号光强。In a specific implementation, the signal processing unit 3 is conventionally provided with amplification, filtering and demodulation parts; the light collection and coupling system 4 is provided as a lens or lens group, which is used to adjust the output light intensity of the tunable fiber laser 1 and the output light from the measured object 5 The light intensity of the feedback light signal.

如图2所示,设置可调谐光纤激光器1的结构形式为:采用线形腔结构的谐振腔体,谐振腔体由设置在可调谐光纤激光器1的前端面位置处的窄带反射镜9和后端面位置处的宽带反射镜8组成;由波分复用器件10将泵浦单元6输出的泵浦光接入谐振腔体,以泵浦光激发谐振腔体内的有源增益介质11在谐振腔体内产生激光;波分复用器件10的输出端连接耦合器12的输入端;以耦合器12的第一输出端13连接光收集与耦合系统4,以耦合器12的第二输出端14连接光电信号转换单元2;设置调谐单元7为调谐功能器件,如压电陶瓷等,通过调谐单元7的调谐作用使可调谐光纤激光器1从耦合器12的第一输出端13输出调谐频率为νm、调谐幅度为Δλ的激光信号。As shown in Figure 2, the structural form of the tunable fiber laser 1 is: a resonant cavity with a linear cavity structure, and the resonant cavity is composed of a narrow-band reflector 9 and a rear end surface arranged at the front end of the tunable fiber laser 1. The broadband reflector 8 at the position is composed; the pump light output by the pump unit 6 is connected to the resonant cavity by the wavelength division multiplexing device 10, and the active gain medium 11 in the resonant cavity is excited by the pump light in the resonant cavity Generate laser light; the output end of the wavelength division multiplexing device 10 is connected to the input end of the coupler 12; the first output end 13 of the coupler 12 is connected to the light collection and coupling system 4, and the second output end 14 of the coupler 12 is connected to the photoelectric Signal conversion unit 2; the tuning unit 7 is set as a tuning function device, such as piezoelectric ceramics, etc., through the tuning function of the tuning unit 7, the tunable fiber laser 1 is output from the first output port 13 of the coupler 12. The tuning frequency is ν m , Tune the laser signal with amplitude Δλ.

在这一技术方案中,宽带反射镜8可以设置为光纤环镜反射镜或介质膜光纤反射镜,窄带反射镜9设置为具有选频功能的光纤光栅。In this technical solution, the broadband reflector 8 can be set as a fiber loop mirror or a dielectric film fiber reflector, and the narrowband reflector 9 can be set as a fiber grating with a frequency selection function.

如图3所示,设置可调谐光纤激光器1的结构形式为:采用环形腔结构的谐振腔体,由波分复用器件10将泵浦单元6输出的泵浦光接入环形腔结构的谐振腔体中,以泵浦光激发谐振腔体内的有源增益介质11,并经过窄带反射镜9在谐振腔体内产生激光;耦合器12的输入端与环形腔结构的谐振腔体连接,耦合器12的第一输出端13连接窄带反射镜9,调谐单元7连接光收集与耦合系统4,耦合器12的第二输出端14连接光电信号转换单元2;设置调谐单元7为调谐功能器件,如压电陶瓷等,通过调谐单元7的调谐作用使可调谐光纤激光器1从窄带反射镜9输出端16输出调谐频率为νm、调谐幅度为Δλ的激光信号。As shown in Figure 3, the structural form of the tunable fiber laser 1 is: a resonant cavity with a ring cavity structure is used, and the pump light output by the pump unit 6 is connected to the resonator of the ring cavity structure by a wavelength division multiplexing device 10. In the cavity, the active gain medium 11 in the cavity is excited by pump light, and laser light is generated in the cavity through a narrow-band mirror 9; the input end of the coupler 12 is connected to the cavity of the ring cavity structure, and the coupler The first output end 13 of 12 is connected with the narrow-band reflector 9, the tuning unit 7 is connected with the light collection and coupling system 4, and the second output end 14 of the coupler 12 is connected with the photoelectric signal conversion unit 2; the tuning unit 7 is set as a tuning function device, such as Piezoelectric ceramics, etc., through the tuning function of the tuning unit 7, the tunable fiber laser 1 outputs a laser signal with a tuning frequency of ν m and a tuning amplitude of Δλ from the output terminal 16 of the narrow-band mirror 9 .

窄带反射镜9设置为具有选频功能的光纤光栅,在有源光纤11和耦合器12之间加入一隔离器15,由隔离器15隔离反馈光控制激光在谐振腔体中的单向传输。The narrowband reflector 9 is set as a fiber grating with frequency selection function. An isolator 15 is added between the active fiber 11 and the coupler 12. The isolator 15 isolates the feedback light to control the unidirectional transmission of the laser in the resonant cavity.

具体实施中,将光纤光栅缠绕在受周期性信号驱动的压电陶瓷上,压电陶瓷导致光纤光栅产生拉伸或收缩,从而光栅常数发生周期性变化,实现可调谐激光器输出激光波长的周期性变化。可在激光器谐振腔内加入偏振控制器,控制激光的偏振状态以消除光纤双折射带来的影响,保证输出激光稳定。In the specific implementation, the fiber grating is wound on the piezoelectric ceramic driven by a periodic signal, and the piezoelectric ceramic causes the fiber grating to stretch or shrink, so that the grating constant changes periodically, and the periodicity of the output laser wavelength of the tunable laser is realized. Variety. A polarization controller can be added to the laser resonator to control the polarization state of the laser to eliminate the influence of fiber birefringence and ensure the stability of the output laser.

周期性信号如三角波信号作用于压电陶瓷,在压电陶瓷作用下光纤光栅发生应变,根据:Periodic signals such as triangular wave signals act on piezoelectric ceramics, and the fiber grating strains under the action of piezoelectric ceramics, according to:

ΔλΔλ FBGFBG λλ FBGFBG == (( 11 -- PP )) ΔϵΔϵ -- -- -- (( 88 ))

式(8)中,λFBG为光栅反射中心波长,ΔλFBG为光栅反射中心波长改变量,P为有效弹光系数,Δε为轴向应变的改变量。当施加力为拉力时,光栅常数增大,光栅反射中心波长往长波方向移动;反之,朝短波方向移动,从而实现波长可调谐的输出。In formula (8), λ FBG is the center wavelength of grating reflection, Δλ FBG is the change amount of grating reflection center wavelength, P is the effective elastic-optics coefficient, and Δε is the change amount of axial strain. When the applied force is pulling force, the grating constant increases, and the center wavelength of the grating reflection moves to the long-wave direction; otherwise, it moves to the short-wave direction, thereby realizing a wavelength-tunable output.

Claims (6)

1. a full fiber type laser is from the mixed ranging system, it is characterized in that adopting a tunable optical fiber laser (1), the light that is equipped with photosignal converting unit (2), the signal processing unit (3) with photodetector and the front end that is positioned at described tunable optical fiber laser (1) with described tunable optical fiber laser (1) is collected and coupled system (4); Described tunable laser (1) is collected by light and the output of coupled system (4) is that λ, tuned frequency are ν to the initial wavelength of testee (5) outgoing m, tuning amplitude is the laser signal of Δ λ, and collect the light signal fed back that output with coupled system (4) receives from the scattering surface of testee (5) by light and form laser from mixed signal; Described photosignal converting unit (2) is to be received in the middle laser that forms of described tunable laser (1) from mixed signal and to be converted to the signal of telecommunication with photodetector; Described signal processing unit (3) receives and handles the signal of telecommunication from described photosignal converting unit (2), utilizes laser from the vibration frequency Δ ν of mixed signal L, obtained the distance L between the output end face of the scattering surface of testee (5) and tunable optical fiber laser (1) by formula (1) Ext:
L ext = Δv L λ 2 4 v m Δλ - - - ( 1 ) .
2. full fiber type laser according to claim 1 is from the mixed ranging system, it is characterized in that: the version that described tunable optical fiber laser (1) is set is: adopt the resonant cavity of linear cavity structure, described resonant cavity is made up of the narrowband reflection mirror (9) of the front end face position that is arranged on tunable optical fiber laser (1) and the broadband mirrors (8) of rear end face position; By the pump light access resonant cavity of wavelength division multiplex device (10) with pump unit (6) output, excite the active gain medium (11) in the resonant cavity in described resonant cavity, to produce laser with described pump light; The output of described wavelength division multiplex device (10) connects the input of coupler (12); First output (13) with described coupler (12) connects described light collection and coupled system (4), with second output (14) the connection described photosignal converting unit (2) of described coupler (12); It is the tuber function device that tuned cell (7) is set, and it is ν from first output (13) the output tuned frequency of described coupler (12) that the tunning effect by described tuned cell (7) makes described tunable optical fiber laser (1) m, tuning amplitude is the laser signal of Δ λ.
3. full fiber type laser according to claim 2 is from the mixed ranging system, it is characterized in that: described broadband mirrors (8) is set to fiber loop mirror speculum or deielectric-coating fiber reflector, the fiber grating that described narrowband reflection mirror (9) is set to have the frequency-selecting function.
4. full fiber type laser according to claim 1 is from the mixed ranging system, it is characterized in that: the version that described tunable optical fiber laser (1) is set is: the resonant cavity that adopts ring cavity structure, inserted in the resonant cavity of ring cavity structure by the pump light of wavelength division multiplex device (10) with pump unit (6) output, excite active gain medium (11) in the resonant cavity with described pump light, and in described resonant cavity, produce laser through narrowband reflection mirror (9); The input of coupler (12) is connected with the resonant cavity of described ring cavity structure, first output (13) of coupler (12) connects narrowband reflection mirror (9), tuned cell (7) connects described light to be collected and coupled system (4), and second output (14) of coupler (12) connects described photosignal converting unit (2); It is the tuber function device that tuned cell (7) is set, and it is ν from described narrowband reflection mirror (9) output (16) output tuned frequency that the tunning effect by described tuned cell (7) makes described tunable optical fiber laser (1) m, tuning amplitude is the laser signal of Δ λ.
5. full fiber type laser according to claim 4 is from the mixed ranging system, it is characterized in that: the fiber grating that described narrowband reflection mirror (9) is set to have the frequency-selecting function, between Active Optical Fiber (11) and coupler (12), add an isolator (15), isolate the one-way transmission of feedback light control laser in described resonant cavity by described isolator (15).
6. full fiber type laser according to claim 1 is from the mixed ranging system, it is characterized in that described light is collected with coupled system (4) is set to lens or set of lenses, is used for regulating the output intensity of described tunable optical fiber laser (1) and from the light signal fed back light intensity of described testee (5).
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