Spectrum modulation method for air plasma generated terahertz wave and light path system

A plasma and modulation method technology, applied in the field of optics, can solve the problems of poor modulation effect, complex optical path system, and low pump light energy utilization rate, and achieve the effect of simple operation, simple optical path system, and improved energy utilization rate

Active Publication Date: 2017-03-29
CAPITAL NORMAL UNIVERSITY
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Problems solved by technology

[0006] The purpose of the present invention is to overcome the problems of poor modulation effect on terah

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  • Spectrum modulation method for air plasma generated terahertz wave and light path system
  • Spectrum modulation method for air plasma generated terahertz wave and light path system
  • Spectrum modulation method for air plasma generated terahertz wave and light path system

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Embodiment Construction

[0052] The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0053] The spectrum modulation method for terahertz waves generated by air plasma in the embodiment of the present invention uses a spatial light modulator to load a lens phase map in the propagation path of a beam of femtosecond pulsed laser, so that the wavefront phase of the femtosecond pulsed laser is changed , after the convergence, two front and rear focal points are generated, and two air plasma filaments are formed at the two focal points, and two terahertz waves are radiated. When the size and spacing of two air plasma filaments are within a certain range of values, interference will occur, and finally a terahertz wave after interference superposition will be obtained. Therefore, by adjusting the phase distribution state on the lens phase diagram, the size and spacing of the two generated air plasma filaments ...

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Abstract

The invention relates to a modulation method for air plasma generated terahertz wave; the method comprises the steps of first, designing a lens phase diagram that is a phase distribution diagram of lens phase factors; second, loading the lens phase diagram to a light path system for air plasma generated terahertz wave so as to generate plasma filaments and to irradiate terahertz wave; the step of designing the lens phase diagram in the first step includes: a, adjusting phase distribution of the lens phase diagram, and using the light path system for air plasma generated terahertz wave to generate terahertz wave; b, studying relationship between the spectrum of the generated terahertz wave and the form of generated plasmas; c, setting the spectrum of terahertz wave expectedly to be generated, calculating spacing of two plasmas that generate the terahertz wave; d, calculating equivalent focal length f1 of the lens phase diagram; e, designing the lens phase diagram. The method according to the embodiments of the invention is simple to perform, dynamic modulation is provided for the spectrum of terahertz wave, and energy utilization rate is increased.

Description

technical field [0001] The invention relates to the field of optics, in particular to a spectrum modulation method and an optical path system for generating terahertz waves by air plasma. Background technique [0002] Since the vibration and rotational energy levels of many polar macromolecules fall within the terahertz spectrum range, terahertz waves can be used for spectrum measurement and identification of substances. Different substances have different spectrum distributions, commonly known as the “fingerprint” of substances. Therefore, terahertz waves are widely used in the fields of security detection, detection and identification of biopharmaceuticals, drugs and explosives. [0003] The method of ionizing air to induce plasma to generate terahertz waves is that when high-energy ultrashort laser pulses are focused in the air, the air at the focal point will be ionized to form plasma, and then radiate terahertz waves. This method has the least terahertz loss, which mak...

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Application Information

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IPC IPC(8): G01N21/3586
CPCG01N21/3586G01N2201/0662
Inventor 孙文峰张颖王新柯张岩
Owner CAPITAL NORMAL UNIVERSITY
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