CN101324734A - Device for Generating Tunable Narrowband Terahertz Waves Using Optical Difference Frequency - Google Patents

Abstract

Translated fromChinese

本发明涉及一种产生太赫兹波的装置，尤其是一种利用光学差频产生可调谐窄带太赫兹波的装置。该装置包括抽运光源，闲频光源，非线性晶体和控制器；非线性晶体设置在抽运光源和闲频光源发射的共线光束的光路上，控制器分别与闲频光源和非线性晶体相接。本发明为解决背景技术中的利用光学方法产生THz辐射的技术问题，而提供了一种利用光学差频产生可调谐窄带太赫兹波的装置，该装置结构简单紧凑容易操作调试、实现了窄带THz波输出的快速连续及可调谐、THz波的输出稳定性高。

The invention relates to a device for generating terahertz waves, in particular to a device for generating tunable narrow-band terahertz waves by using optical difference frequency. The device includes a pumping light source, an idler light source, a nonlinear crystal and a controller; the nonlinear crystal is arranged on the optical path of the collinear light beams emitted by the pumping light source and the idler light source, and the controller is connected with the idler light source and the nonlinear crystal respectively. connect. In order to solve the technical problem of using optical methods to generate THz radiation in the background technology, the present invention provides a device for generating tunable narrow-band terahertz waves by using optical difference frequency. The device has a simple and compact structure, is easy to operate and debug, and realizes narrow-band THz Rapid continuous and tunable wave output, high stability of THz wave output.

Description

Translated fromChinese

利用光学差频产生可调谐窄带太赫兹波的装置Device for Generating Tunable Narrowband Terahertz Waves Using Optical Difference Frequency

技术领域technical field

本发明涉及一种产生太赫兹波的装置，尤其是一种利用光学差频产生可调谐窄带太赫兹波的装置。The invention relates to a device for generating terahertz waves, in particular to a device for generating tunable narrow-band terahertz waves by using optical difference frequency.

背景技术Background technique

太赫兹波(Tera-Hertz Wave，THz波)是指频率在0.1-10THz范围内的电磁波。它是光子学技术与电子学技术、宏观与微观的过渡区域，是一个具有科学研究价值但尚未开发的电磁辐射区域。它在长波段与毫米波、亚毫米波相重合，而在短波段与红外线相重合，在电磁波谱中占有一个很特殊的位置。太赫兹这一位置正好处于科学技术发展相对较好的微波毫米波与红外线光学之间，但由于THz波源问题一直未能得到很好的解决，因此形成了一个在研究上相对落后的“空白”。太赫兹在长波方向主要依靠电子学技术，而在短波方向则主要依靠光子学技术，在电子学与光子学之间的这一“空白”蕴含着深刻的物理含义。Terahertz wave (Tera-Hertz Wave, THz wave) refers to electromagnetic waves with a frequency in the range of 0.1-10THz. It is a transition area between photonics technology and electronic technology, macroscopic and microscopic, and an electromagnetic radiation area that has scientific research value but has not yet been developed. It coincides with millimeter waves and submillimeter waves in the long wave band, and coincides with infrared rays in the short wave band, occupying a very special position in the electromagnetic spectrum. The position of terahertz is just between microwave and millimeter wave and infrared optics, which are relatively well developed in science and technology. However, because the problem of THz wave source has not been well resolved, a relatively backward "blank" has been formed in research. . Terahertz mainly relies on electronics technology in the long-wave direction, and photonics technology in the short-wave direction. This "gap" between electronics and photonics has profound physical meaning.

由于THz辐射波在电磁波谱中所处的特殊位置，所以它具有以下独特性质：Due to the special position of THz radiation wave in the electromagnetic spectrum, it has the following unique properties:

1、由于THz波的频率很高(波长比微波小1000陪以上)，所以其空间分辨率很高；1. Since the frequency of THz waves is very high (the wavelength is more than 1000 times smaller than that of microwaves), its spatial resolution is very high;

2、由于脉冲可以很短(飞秒)，THz辐射具有很高的时间分辨率；2. Since the pulse can be very short (femtoseconds), THz radiation has a high time resolution;

3、THz辐射的能量很小，不会对物质产生破坏作用，所以与X射线相比，它又有很大的优势；d)THz的时域频谱信噪比很高，这使得THz非常适用于成像应用。THz成像技术及THz波谱技术构成了THz应用的两个主要关键技术。3. The energy of THz radiation is very small and will not cause damage to matter, so it has great advantages compared with X-rays; d) THz time-domain spectrum signal-to-noise ratio is very high, which makes THz very suitable for imaging applications. THz imaging technology and THz spectrum technology constitute the two main key technologies for THz applications.

由于THz波独特的性质，使它在国家安全、国民经济和科学研究等领域具有非常重要的多方面的应用：THz系统在国土安全检测(例如毒品、爆炸物、化学/生物危险品和武器等的非接触安全检测、邮件隐藏物的非接触监测等)、国防和THz雷达(如远程监视、探测武器以及在战场上用于显示前方灰尘或烟雾中的坦克等，远距离成像、多光谱成像以及三维立体成像等)、半导体材料、高温超导材料的性质研究、断层成像技术、无标记的基因检查、细胞水平的成像，以及宽带通信(例如卫星间星际通信、短程大气通信、短程地面无线局域网等)等许多领域有广泛的应用。Due to the unique nature of THz waves, it has very important and multifaceted applications in the fields of national security, national economy and scientific research: THz systems are used in homeland security detection (such as drugs, explosives, chemical/biological hazards and weapons, etc. Non-contact security detection, non-contact monitoring of mail hidden objects, etc.), national defense and THz radar (such as long-range surveillance, detection of weapons, and used on the battlefield to show tanks in front of dust or smoke, etc., long-range imaging, multi-spectral imaging and three-dimensional imaging, etc.), semiconductor materials, properties of high-temperature superconducting materials, tomography, marker-free genetic inspection, imaging at the cellular level, and broadband communications (such as interstellar interstellar communications, short-range atmospheric communications, short-range terrestrial wireless LAN, etc.) and many other fields have a wide range of applications.

THz辐射源研究是THz科学技术发展的重要环节，如何有效的产生高功率(高能量)、高效率且能在室温下稳定运转、宽带可调谐的THz辐射源，已经成为THz技术与应用领域研究及发展的关键。THz辐射产生的方法有两大类：一类是利用电子学的方法，另一类是利用光学的方法。目前，电子学方法的转换效率都很低，辐射功率多在毫瓦量级以下，而且体积庞大，造价和运行成本很高，对运行环境要求高。The research on THz radiation sources is an important link in the development of THz science and technology. How to effectively generate high-power (high-energy), high-efficiency, stable operation at room temperature, and wide-band tunable THz radiation sources has become a research topic in the field of THz technology and applications. and the key to development. There are two types of THz radiation generation methods: one is the method of using electronics, and the other is the method of using optics. At present, the conversion efficiency of electronic methods is very low, and the radiation power is mostly below the milliwatt level, and the volume is large, the cost of construction and operation is high, and the requirements for the operating environment are high.

而与电子学方法相比，利用光学参量技术的光学方法产生THz辐射在理论上具有实现高效率、室温运转、高功率且稳定的输出、窄频带输出和宽频带范围连续可调谐等优点。因此，光学THz辐射源技术是目前THz辐射产生的主要发展方向，然而目前国内外仍未有具体的利用光学方法产生THz辐射的装置。Compared with the electronic method, the optical method using optical parametric technology to generate THz radiation has theoretically the advantages of high efficiency, room temperature operation, high power and stable output, narrow-band output and wide-band continuous tunability. Therefore, optical THz radiation source technology is the main development direction of THz radiation generation at present. However, there is still no specific device for generating THz radiation by optical methods at home and abroad.

发明内容Contents of the invention

本发明为解决背景技术中存在的上述技术问题，而提供了一种利用光学差频产生可调谐窄带太赫兹波的装置，该装置结构简单紧凑容易操作调试、实现了窄带THz波输出的快速连续及可调谐、THz波的输出稳定性高。In order to solve the above-mentioned technical problems in the background technology, the present invention provides a device for generating tunable narrow-band THz waves by using optical difference frequency. The device has a simple and compact structure, is easy to operate and debug, and realizes rapid and continuous output of narrow-band THz waves And tunable, THz wave output stability is high.

本发明的技术解决方案是：本发明为一种利用光学差频产生可调谐窄带太赫兹波的装置，其特殊之处在于：该装置包括抽运光源，闲频光源，非线性晶体和控制器；非线性晶体设置在抽运光源和闲频光源发射的共线光束的光路上，控制器分别与闲频光源和非线性晶体相接。The technical solution of the present invention is: the present invention is a device for generating tunable narrow-band terahertz waves by using optical difference frequency, and its special feature is that the device includes a pumping light source, an idler light source, a nonlinear crystal and a controller The nonlinear crystal is arranged on the optical path of the collinear beam emitted by the pumping light source and the idler light source, and the controller is respectively connected with the idler light source and the nonlinear crystal.

上述抽运光源包括单纵模调激光器、衰减器和缩束镜，衰减器和缩束镜依次设置在单纵模调激光器的出射光路上。The above-mentioned pumping light source includes a single longitudinal mode modulated laser, an attenuator and a beam reducer, and the attenuator and the beam reducer are sequentially arranged on the exit optical path of the single longitudinal mode modulated laser.

上述闲频光源包括连续可调的单纵模激光二极管、光纤放大器、闲频光处理装置，连续可调的单纵模激光二极管接入光纤放大器，光纤放大器接入闲频光处理装置，闲频光处理装置包括光纤准直器、隔离器、光束展宽器和第一半波片，光纤准直器、隔离器、光束展宽器和第一半波片依次设置在光纤放大器的出射光路上。The above-mentioned idler light source includes a continuously adjustable single longitudinal mode laser diode, a fiber amplifier, and an idler light processing device. The continuously adjustable single longitudinal mode laser diode is connected to the fiber amplifier, and the fiber amplifier is connected to the idler light processing device. The optical processing device includes a fiber collimator, an isolator, a beam expander and a first half-wave plate, and the fiber collimator, isolator, beam expander and the first half-wave plate are sequentially arranged on the exit light path of the fiber amplifier.

上述闲频光源还包括反射镜和第二半波片，反射镜和第二半波片依次设置在第一半波片和非线性晶体之间。The above-mentioned idler light source also includes a reflector and a second half-wave plate, and the reflector and the second half-wave plate are sequentially arranged between the first half-wave plate and the nonlinear crystal.

上述第二半波片与非线性晶体之间依次还设置有光栅、第一凹面镜和第二凹面镜。A grating, a first concave mirror, and a second concave mirror are arranged sequentially between the second half-wave plate and the nonlinear crystal.

上述非线性晶体是GaSe、ZGP或GaP晶体。The above-mentioned nonlinear crystal is GaSe, ZGP or GaP crystal.

上述非线性晶体后放置有滤波器。A filter is placed after the above-mentioned nonlinear crystal.

上述控制器包括计算机和由计算机控制的旋转平台，非线性晶体设置在旋转平台上。The above-mentioned controller includes a computer and a rotating platform controlled by the computer, and the nonlinear crystal is arranged on the rotating platform.

上述非线性晶体是由相互错开的第一MgO:LiNbO₃晶体和第二MgO:LiNbO₃晶体构成，第二MgO:LiNbO₃晶体表面上设置有硅棱镜阵列。The nonlinear crystal is composed of a first MgO:LiNbO₃ crystal and a second MgO:LiNbO₃ crystal which are staggered from each other, and a silicon prism array is arranged on the surface of the second MgO:LiNbO₃ crystal.

上述控制器包括计算机和由计算机控制的旋转平台，非线性晶体设置在旋转平台上，旋转平台上还设置有由计算机控制反射角度的反射闲频光的反射镜。The above-mentioned controller includes a computer and a rotating platform controlled by the computer. The nonlinear crystal is arranged on the rotating platform, and a reflector for reflecting idler light whose reflection angle is controlled by the computer is also arranged on the rotating platform.

本发明具有以下优点：The present invention has the following advantages:

1、本发明结构简单紧凑，容易操作调试。1. The structure of the present invention is simple and compact, and it is easy to operate and debug.

2、本发明利用连续可调的单纵模激光二极管和掺镱光纤放大器结合建立了可调谐的窄带种子源系统，窄带种子光作为闲频光注入光参量发生器，通过控制器对晶体的相位匹配角的控制，实现相位匹配角与注入调谐波长完全一致，从而实现了窄带THz波输出的快速连续及可调谐。2. The present invention uses a continuously adjustable single longitudinal mode laser diode and an ytterbium-doped fiber amplifier to combine to establish a tunable narrowband seed source system. The narrowband seed light is injected into the optical parameter generator as idler light, and the phase of the crystal is controlled by the controller. The control of the matching angle realizes that the phase matching angle is completely consistent with the injection tuning wavelength, thereby realizing the rapid continuous and tunable narrowband THz wave output.

3、本发明可以通过优化选择晶体长度、抽运光强和注入闲频光强使参量过程处于深度增益饱和状态，从而提高THz波的输出稳定性，同时通过放大闲频光功率可实现THz波高功率输出。3. The present invention can make the parametric process in a state of deep gain saturation by optimizing the crystal length, pumping light intensity and injection idler light intensity, thereby improving the output stability of THz waves, and at the same time, the THz wave height can be realized by amplifying the idler light power power output.

附图说明Description of drawings

图1是本发明利用非线性晶体产生THz波的原理示意图；Fig. 1 is the schematic diagram of the principle that the present invention utilizes nonlinear crystal to generate THz wave;

图2是本发明的结构框图；Fig. 2 is a structural block diagram of the present invention;

图3是本发明实施例一的结构示意图；Fig. 3 is a schematic structural view ofEmbodiment 1 of the present invention;

图4是本发明实施例二的结构示意图。Fig. 4 is a schematic structural diagram ofEmbodiment 2 of the present invention.

具体实施方式Detailed ways

参见图1，当频率为ω_p的强抽运光和频率为ω_i的小信号闲频光同时入射到二阶非线性光学介质上时，在介质中产生三波混频作用，结果将产生出频率为ω_T(＝ω_p-ω_i)的信号波输出，同时入射光能量从抽运光转移到闲频光和信号波中。在此过程中必须满足能量和动量守恒条件：Referring to Fig. 1, when the strong pumping light with frequency ω_p and the small idler light with frequency ω_i are incident on the second-order nonlinear optical medium at the same time, three-wave mixing will occur in the medium, and the result will be A signal wave with a frequency of ω_T (=ω_p -ω_i ) is output, while the energy of the incident light is transferred from the pumping light to the idler light and the signal wave. The energy and momentum conservation conditions must be satisfied during this process:

ω_p＝ω_T+ω_i    (1)ω_p = ω_T + ω_i (1)

其中，|k_m|＝2πn_m/λ_m(m＝P，T，i)，n_m为非线性晶体的折射率。(2)式又称相位匹配条件。对于各向异性介质，可以通过角度调谐或温度调谐来实现相位匹配。Wherein, |k_m |=2πn_m /λ_m (m=P, T, i), and_nm is the refractive index of the nonlinear crystal. (2) is also called the phase matching condition. For anisotropic media, phase matching can be achieved by angle tuning or temperature tuning.

以GaSe晶体为例：按照o-e＝e的共线相位匹配类型切割GaSe晶体。抽运光为寻常光偏振(o光)，闲频光为非常光偏振(e光)，利用以下公式和晶体的Sellmeier方程联合求解，可得到相位匹配角θTake GaSe crystal as an example: the GaSe crystal is cut according to the collinear phase matching type of o-e=e. The pump light is ordinary light polarization (o light), and the idler light is extraordinary light polarization (e light). Using the following formula and the Sellmeier equation of the crystal to solve jointly, the phase matching angle θ can be obtained

$\frac{\mathrm{<span><span>1</span>1</span>}}{{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>p</span>p</span>}}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>1</span>1</span>}}{{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>i</span>i</span>}}}<span><span>+</span>+</span>\frac{\mathrm{<span><span>1</span>1</span>}}{{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>T</span>T</span>}}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>3</span>3</span>}<span><span>)</span>)</span>$

$\frac{{\mathrm{<span><span>n</span>no</span>}}_{\mathrm{<span><span>p</span>p</span>}}<span><span>(</span>(</span>{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>p</span>p</span>}}<span><span>)</span>)</span>}{{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>p</span>p</span>}}}<span><span>-</span>-</span>\frac{{\mathrm{<span><span>n</span>no</span>}}_{\mathrm{<span><span>t</span>t</span>}}<span><span>(</span>(</span>{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>i</span>i</span>}}<span><span>,</span>,</span>\mathrm{<span><span>\&theta;</span>\&theta;</span>}<span><span>)</span>)</span>}{{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>i</span>i</span>}}}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>n</span>no</span>}}_{\mathrm{<span><span>T</span>T</span>}}<span><span>(</span>(</span>{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>T</span>T</span>}}<span><span>,</span>,</span>\mathrm{<span><span>\&theta;</span>\&theta;</span>}<span><span>)</span>)</span>}{{\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}}_{\mathrm{<span><span>T</span>T</span>}}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>4</span>4</span>}<span><span>)</span>)</span>$

$\frac{\mathrm{<span><span>1</span>1</span>}}{{\mathrm{<span><span>n</span>no</span>}}_{\mathrm{<span><span>e</span>e</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}<span><span>,</span>,</span>\mathrm{<span><span>\&theta;</span>\&theta;</span>}<span><span>)</span>)</span>}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>cos</span>cos</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>\mathrm{<span><span>\&theta;</span>\&theta;</span>}<span><span>)</span>)</span>}{{\mathrm{<span><span>n</span>no</span>}}_{\mathrm{<span><span>o</span>o</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}<span><span>)</span>)</span>}<span><span>+</span>+</span>\frac{{\mathrm{<span><span>sin</span>sin</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>\mathrm{<span><span>\&theta;</span>\&theta;</span>}<span><span>)</span>)</span>}{{\mathrm{<span><span>n</span>no</span>}}_{\mathrm{<span><span>e</span>e</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}<span><span>)</span>)</span>}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>5</span>5</span>}<span><span>)</span>)</span>$

其中λ_p＝1.064μm是抽运光波长，λ_i是闲频光波长，λ_T是THz波长，θ是相位匹配角。Where λ_p =1.064 μm is the wavelength of the pump light, λ_i is the wavelength of the idler light, λ_T is the THz wavelength, and θ is the phase matching angle.

因此，利用波长为λ_p，高功率，单纵模的抽运光源和波长为λ_i，在抽运光波长λ_p附近且宽范围连续可调谐的闲频光源共线入射到非线性晶体上，利用非线性晶体的二阶非线性效应实现差频过程，就可产生窄带太赫兹波。Therefore, using a high-power, single-longitudinal-mode pump light source with a wavelength of λ p and a_wavelength of λ_i , an idler frequency light source near the pump wavelength λ_p and continuously tunable in a wide range is collinearly incident on the nonlinear crystal , using the second-order nonlinear effect of the nonlinear crystal to realize the difference frequency process, the narrow-band terahertz wave can be generated.

参见图2，本发明包括抽运光源1，闲频光源3，非线性晶体2和控制器4；非线性晶体2设置在抽运光源1和闲频光源3发射的共线光束的光路上，控制器4分别与闲频光源3和非线性晶体2相接。利用高功率、单纵模的抽运光源1和宽范围连续可调谐的闲频光源3共线入射到非线性晶体2上，以及非线性晶体2的二阶非线性效应实现差频过程，就可产生窄带太赫兹波。Referring to Fig. 2, the present invention comprises pumpinglight source 1, idlerlight source 3,nonlinear crystal 2 andcontroller 4; Thecontroller 4 is connected to the idlerlight source 3 and thenonlinear crystal 2 respectively. Using the high-power, single-longitudinal-modepumping light source 1 and the wide-range continuously tunable idler frequencylight source 3 collinearly incident on thenonlinear crystal 2, and the second-order nonlinear effect of thenonlinear crystal 2 to realize the difference frequency process, it is Narrowband terahertz waves can be generated.

参见图3，本发明的一个具体实施例中：抽运光源1包括单纵模调激光器5、衰减器6和缩束镜7，衰减器6和缩束镜7依次设置在单纵模调激光器5的出射光路上，其中单纵模调激光器5具体可采用单纵模调Q Nd:YAG激光器，用半波片和偏振片组成的衰减器6来控制选择合适的抽运光脉冲能量，用缩束镜7将抽运光缩束来控制抽运光的光强；闲频光源3包括连续可调的单纵模激光二极管11、光纤放大器12、闲频光处理装置13，连续可调的单纵模激光二极管11接入光纤放大器12，光纤放大器12接入闲频光处理装置13，其中，连续可调的单纵模激光二极管11具体可采用可调ECLD，光纤放大器12具体可采用掺镱光纤放大器，闲频光处理装置13包括光纤准直器FC、隔离器ISO、光束展宽器BE和第一半波片，光纤准直器FC、隔离器ISO、光束展宽器BE和第一半波片依次设置在光纤放大器12的出射光路上。采用连续可调的单纵模激光二极管11输出的连续光作为种子光，再通过光纤放大器12将种子光功率放大，再经闲频光处理装置13准直、扩束和转偏处理后作为闲频光与抽运光束通过双色镜8共线入射到非线性晶体2中，双色镜8可透射抽运光，反射闲频光，闲频光源3还可包括反射镜14和第二半波片，反射镜14和第二半波片依次设置在第一半波片和非线性晶体2之间。非线性晶体2选用在THz波范围吸收系数比较小的晶体如GaSe，ZGP和GaP等晶体，以选用GaSe晶体为佳；GaSe晶体9固定于可编程精密控制的旋转平台15上，通过计算机16精密控制连续扫描调谐连续可调的单纵模激光二极管11的输出波长和同步调谐GaSe晶体9的角度相位匹配角来实现快速连续光滑可调谐的窄带THz波输出。在GaSe晶体9后放置滤波器10滤去抽运光和闲频光。Referring to Fig. 3, in a specific embodiment of the present invention: the pumpinglight source 1 includes a single longitudinal mode modulatedlaser 5, anattenuator 6 and abeam reducer 7, and theattenuator 6 and thebeam reducer 7 are sequentially arranged on the single longitudinal mode modulatedlaser 5, wherein the single longitudinal mode modulatedlaser 5 can specifically adopt a single longitudinal mode Q-switched Nd:YAG laser, and anattenuator 6 composed of a half-wave plate and a polarizer is used to control and select the appropriate pumping light pulse energy. Thebeam shrinker 7 shrinks the pumping light to control the light intensity of the pumping light; the idlerlight source 3 includes a continuously adjustable single longitudinalmode laser diode 11, anoptical fiber amplifier 12, and an idlerlight processing device 13, and the continuously adjustable The single longitudinalmode laser diode 11 is connected to thefiber amplifier 12, and thefiber amplifier 12 is connected to the idlerlight processing device 13, wherein the continuously adjustable single longitudinalmode laser diode 11 can specifically adopt an adjustable ECLD, and thefiber amplifier 12 can specifically adopt a doped Ytterbium fiber amplifier, idlerlight processing device 13 includes fiber collimator FC, isolator ISO, beam expander BE and the first half-wave plate, fiber collimator FC, isolator ISO, beam expander BE and the first half-wave plate The wave plates are sequentially arranged on the outgoing light path of thefiber amplifier 12 . The continuous light output by the continuously adjustable single longitudinalmode laser diode 11 is used as the seed light, and then the power of the seed light is amplified by thefiber amplifier 12, and then processed by the idlerlight processing device 13 for collimation, beam expansion and deflection as the idler light. The frequency light and the pumping light beam are collinearly incident into thenonlinear crystal 2 through thedichroic mirror 8, thedichroic mirror 8 can transmit the pumping light and reflect the idler light, and the idlerlight source 3 can also include areflector 14 and a second half-wave plate , thereflector 14 and the second half-wave plate are sequentially arranged between the first half-wave plate and thenonlinear crystal 2 . Thenonlinear crystal 2 selects crystals such as GaSe, ZGP and GaP crystals with relatively small absorption coefficients in the THz wave range, preferably GaSe crystals; The output wavelength of the continuously adjustable single longitudinalmode laser diode 11 is controlled by continuous scan tuning and the angular phase matching angle of theGaSe crystal 9 is synchronously tuned to realize fast continuous smooth tunable narrow-band THz wave output. Afilter 10 is placed after theGaSe crystal 9 to filter out pumping light and idler light.

参见图4，非线性晶体2是由相互错开的第一MgO:LiNbO₃晶体18和第二MgO:LiNbO₃晶体20构成，第二MgO:LiNbO₃晶体20表面上设置有硅棱镜阵列19耦合输出THz波，旋转平台15上还设置有由计算机16控制反射角度的反射闲频光的反射镜。通过计算机16精密控制不同波长的闲频光的反射角度使之满足在非线性晶体2中的相位匹配，可以实现THz的连续可调输出。Referring to Fig. 4, thenonlinear crystal 2 is composed of a first MgO:LiNbO₃ crystal 18 and a second MgO:LiNbO₃ crystal 20 which are staggered from each other, and asilicon prism array 19 is arranged on the surface of the second MgO:LiNbO₃ crystal 20 to couple out For THz waves, the rotatingplatform 15 is also provided with a reflector for reflecting idler light whose reflection angle is controlled by acomputer 16 . Thecomputer 16 precisely controls the reflection angles of the idler lights of different wavelengths to meet the phase matching in thenonlinear crystal 2, so that the continuously adjustable output of THz can be realized.

本发明还可通过光栅和凹面镜的组合调节闲频光使不同波长的闲频光注入晶体中满足相位匹配条件，实现THz波的快速可调谐输出。在该实施例中由光栅21、第一凹面镜(CM1)22和第二凹面镜(CM2)17组合而成，光栅21、第一凹面镜22和第二凹面镜17设置在第二半波片与非线性晶体2之间，闲频光光束经过光栅21被散射，能够对不同波长的闲频光实现色散补偿，使之自动满足相位匹配条件；第一凹面镜22和第二凹面镜17组成了望远镜系统，使被光栅21散射的光束会聚注入非线性晶体2中。The invention can also adjust the idler light through the combination of the grating and the concave mirror, so that the idler light of different wavelengths is injected into the crystal to meet the phase matching condition, and realizes the fast tunable output of THz wave. In this embodiment, it is composed of a grating 21, a first concave mirror (CM1) 22 and a second concave mirror (CM2) 17, and the grating 21, the firstconcave mirror 22 and the secondconcave mirror 17 are arranged at the second half-wave Between the sheet and thenonlinear crystal 2, the idler light beam is scattered by the grating 21, which can realize dispersion compensation for the idler light of different wavelengths, so that it automatically meets the phase matching condition; the firstconcave mirror 22 and the second concave mirror 17 A telescope system is formed so that the light beam scattered by the grating 21 is converged and injected into thenonlinear crystal 2 .

Claims (10)

1, a kind of device that utilizes optical difference frequency to produce tunable narrow band terahertz band wave, it is characterized in that: this device comprises pump light source, ideler frequency light source, nonlinear crystal and controller; Described nonlinear crystal is arranged on the light path of co-linear beams of pump light source and ideler frequency light emitted, and described controller joins with ideler frequency light source and nonlinear crystal respectively.

2, the device that utilizes optical difference frequency to produce tunable narrow band terahertz band wave according to claim 1, it is characterized in that: described pump light source comprises single longitudinal mode adjusting laser, attenuator and beam-shrinked mirror, and described attenuator and beam-shrinked mirror are successively set on the emitting light path of single longitudinal mode adjusting laser.

3, the device that utilizes optical difference frequency to produce tunable narrow band terahertz band wave according to claim 1, it is characterized in that: described ideler frequency light source comprises continuously adjustable single longitudinal mode laser diode, fiber amplifier, the ideler frequency light processor, described continuously adjustable single longitudinal mode laser diode incoming fiber optic amplifier, described fiber amplifier inserts the ideler frequency light processor, described ideler frequency light processor comprises optical fiber collimator, isolator, the beam broadening device and first half-wave plate, described optical fiber collimator, isolator, the beam broadening device and first half-wave plate are successively set on the emitting light path of fiber amplifier.

4, the device that utilizes optical difference frequency to produce tunable narrow band terahertz band wave according to claim 3, it is characterized in that: described ideler frequency light source also comprises the catoptron and second half-wave plate, and the described catoptron and second half-wave plate are successively set between first half-wave plate and the nonlinear crystal.

5, the device that utilizes optical difference frequency to produce tunable narrow band terahertz band wave according to claim 4 is characterized in that: also be provided with grating, first concave mirror and second concave mirror between described second half-wave plate and the nonlinear crystal successively.

6, according to claim 1 or 2 or 3 or 4 or 5 described a kind of devices that utilize optical difference frequency to produce tunable narrow band terahertz band wave, it is characterized in that: but described nonlinear crystal GaSe, ZGP or GaP crystal.

7, a kind of device that utilizes optical difference frequency to produce tunable narrow band terahertz band wave according to claim 6 is characterized in that: be placed with wave filter behind the described nonlinear crystal.

8, a kind of device that utilizes optical difference frequency to produce tunable narrow band terahertz band wave according to claim 7, it is characterized in that: described controller comprises computing machine and by computer-controlled rotation platform, described nonlinear crystal is arranged on the rotation platform.

9, according to claim 1 or 2 or 3 or 4 or 5 described a kind of devices that utilize optical difference frequency to produce tunable narrow band terahertz band wave, it is characterized in that: described nonlinear crystal is by a MgO:LiNbO who staggers mutually₃Crystal and the 2nd MgO:LiNbO₃Crystal constitutes, described the 2nd MgO:LiNbO₃Plane of crystal is provided with the silicon prism array.

10, a kind of device that utilizes optical difference frequency to produce tunable narrow band terahertz band wave according to claim 9, it is characterized in that: described controller comprises computing machine and by computer-controlled rotation platform, described nonlinear crystal is arranged on the rotation platform, also is provided with the reflection ideler frequency reflection of light mirror by the computer control reflection angle on the described rotation platform.

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