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Ultra-wide frequency spectrum terahertz wave time domain spectrum coherent detection method and device

A technology of time-domain spectroscopy and detection methods, applied in measuring devices, material analysis through optical means, instruments, etc., can solve problems such as the difficulty of rotating the external electric field, increasing the cost of detection, and the limitation of terahertz polarization detection

Inactive Publication Date: 2017-02-22
CHONGQING INST OF GREEN & INTELLIGENT TECH CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method needs to use an external electric field modulator, which is an external electrical instrument, and the external electric field is not easy to rotate, so it has certain limitations on the polarization detection of terahertz
[0007] The above three coherent detection methods for terahertz wave pulses, the first two are terahertz wave pulses that can detect ordinary bandwidths, and the third method is an ultra-wide spectrum detection method, but requires an additional electric field modulator, which increases the cost of detection

Method used

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Embodiment 1

[0034] This embodiment provides an ultra-wide spectrum terahertz wave time-domain spectral coherent detection device, the structure diagram of the device is shown in the attached figure 1 As shown, 1 is the terahertz wave pulse to be detected; 2 is the optical mechanical chopper; 3 is the 90-degree off-axis off-axis parabolic mirror; 4 is the indium tin oxide semiconductor transparent conductive glass, which is in the same direction as the detection laser pulse direction 45 degree angle; 5 is the linearly polarized detection laser pulse; 6, 7, 9, 10 are a group of laser mirrors; 8 is the electric translation stage; 11 is the focusing lens; 12 is the laser half-wave plate; 13 is β-phase barium metaborate crystal; 14 is a laser fundamental frequency filter with a bandpass of 400±20 nanometers; 15 is a photomultiplier tube.

[0035] After collimation, the terahertz wave pulse 1 to be detected is incident on the optical mechanical chopper 2 for chopping, and then focused by the 90...

Embodiment 2

[0037] This embodiment provides an ultra-wide-spectrum terahertz wave time-domain spectral coherent detection method, which uses the interaction of two-color femtosecond laser pulses and air plasma to generate terahertz wave radiation. In the detection laser, the energy of the laser pulse is 80 microjoules The focusing lens adopts a lens of F=40cm; the half-wave plate adopts an angle of 0 degrees, that is, the polarization direction of the detection laser is not changed; the angle between the fast axis of the β-BBO crystal and the polarization direction of the detection laser is 40 degrees. The chopping frequency of the terahertz wave is 270 Hz. The moving step of the motorized translation stage is 3 microns, that is, the time step is 20 femtoseconds. The scan time window is 13 picoseconds. In an environment with a temperature of 21 degrees Celsius and a relative humidity of 40%, the attached figure 2 It is the measured terahertz wave pulse time-domain waveform (a) and the ...

Embodiment 3

[0039] This embodiment provides an ultra-wide spectrum terahertz wave time-domain spectral coherent detection method. The terahertz wave generation end and the detection end including the device are sealed and filled with dry nitrogen, and the temperature is kept at 21 degrees Celsius and the relative humidity is 20. %, the scanning time window is 5 picoseconds, other parameters are the same as in Embodiment 1, and the time-domain waveform and spectrum of the terahertz wave are re-measured, as shown in the attached image 3 shown. attached image 3 (a) is the time-domain waveform of terahertz wave, and (b) is the corresponding frequency spectrum. Due to the low humidity in such an environment, the absorption of water vapor on terahertz waves is reduced, making the spectrum of terahertz waves smooth. If the relative humidity drops to around 0, the terahertz spectrum will be smoother.

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Abstract

The invention provides an ultra-wide frequency spectrum terahertz wave time domain spectrum coherent detection method and device, and belongs to the field of optoelectronics application. According to the method provided by the invention, the electric field time domain waveform signal of a Terahertz wave pulse is detected through laser secondary harmonic signals generated by the non-linear effect of the laser pulse electric field and the Terahertz wave pulse electric field with air atoms / molecules in air media; the method belongs to a coherent detection method. A frequency doubling light signal generated in the device comprises optical intrinsic oscillation frequency doubling light generated in nonlinear crystals beta-BBO by using detection laser and also comprises detection laser and laser frequency doubling light generated by the Terahertz wave pulse electric field in the air media. The intrinsic oscillation source is generated by using beta-BBO crystals; the size of the oscillation source can be controlled through rotating an inclined angle formed between a fast shaft of the beta-BBO crystals and the polarization direction of the detection laser; the intrinsic oscillation source generation by using an external voltage modulator is not used; the cost is reduced; the detection method is simpler and more convenient; the detection can be performed under the all optical element conditions.

Description

technical field [0001] The invention relates to a terahertz wave time-domain spectral coherent detection method and device, in particular to an ultra-wide spectrum terahertz wave time-domain spectral coherent detection method and device, belonging to the field of optoelectronic applications. Background technique [0002] The terahertz wave has a frequency of 0.1-10 terahertz (1 terahertz = 10 12 Hertz) electromagnetic waves, located between microwaves and infrared in the electromagnetic spectrum, belong to far-infrared electromagnetic waves. The terahertz wave pulse is an ultrashort electromagnetic radiation pulse, its time domain length is several hundred femtoseconds to several picoseconds, and the corresponding spectral width is several terahertz. When the spectral width of the terahertz wave pulse is about 0.1 terahertz, it is generally called narrow-band terahertz wave; when the spectral width of the terahertz wave pulse is greater than 3 terahertz, it is called broad-...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/3586
CPCG01N21/3586
Inventor 彭晓煜董家蒙杜海伟刘毅施长城
Owner CHONGQING INST OF GREEN & INTELLIGENT TECH CHINESE ACADEMY OF SCI
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