CN-121996907-A - Signal correction method for pulse terahertz system

Abstract

The application discloses a signal correction method for a pulse terahertz system, and relates to the technical field of terahertz waves. And calculating a distortion coefficient after obtaining frequency spectrum data of the terahertz signal through the terahertz waveform standard device, correcting frequency domain data of the terahertz signal obtained in the terahertz system through the distortion coefficient, and obtaining a distortion-free terahertz time domain waveform through inverse Fourier transform. The method solves the problems of high cost and easy signal distortion caused by the inherent influence elimination of the system in the current pulse terahertz system.

Inventors

• LIU JIANCHUN
• GONG PENGWEI
• XIE WEN
• JIANG HE
• ZHAO LI
• Miao Shuya

Assignees

• 北京无线电计量测试研究所

Dates

Publication Date

20260508

Application Date

20251223

Claims (3)

1. 1. A signal correction method for a pulsed terahertz system, comprising: Measuring a terahertz waveform of a terahertz generator in a pulse terahertz system by using a terahertz waveform standard device, and carrying out Fourier transform on the time domain waveform to obtain a frequency spectrum F ref of the time domain waveform; in a pulse terahertz system, a terahertz detector in the pulse terahertz system is used for measuring a terahertz signal generated by a terahertz generator, and a time domain waveform of the measured terahertz waveform is subjected to Fourier transform to obtain a frequency spectrum F out of the time domain waveform; Calculating a distortion coefficient D (F), wherein the calculation formula is D (F) = (F out -F ref )/F ref ; When the pulse terahertz system is used again, the frequency spectrum F 1 of the terahertz signal generated by the terahertz generator is measured by using the terahertz detector inside the pulse terahertz system, the frequency spectrum of the terahertz signal after correction is F real (f)＝F 1 /(1+D (F)), and the corrected terahertz signal frequency spectrum can be obtained through inverse Fourier transformation, so that the corrected terahertz time-domain waveform F real (t).
2. 2. The method of claim 1, wherein the pulse waveform parameter sub-reference device is used for accurately measuring the terahertz time-domain waveform generated by the terahertz generation module of the electro-optic crystal, and the device is provided with a complete tracing chain; The pulse type electro-optical sampling terahertz system comprises a laser excitation module, an electro-optical crystal terahertz generation module, an electro-optical detection module and a signal acquisition module, wherein the electro-optical crystal terahertz generation module loads terahertz information onto laser through double refraction effects under laser excitation, the electro-optical detection module receives the laser and converts the laser into a current signal related to a terahertz signal, and the current signal is input into the signal acquisition module to extract the terahertz signal.
3. 3. The method of claim 1, wherein the distortion factor is a frequency dependent function reflecting a degree of distortion of the terahertz signal measured in the pulsed electro-optical sampled terahertz system relative to a standard terahertz time-domain waveform.

Description

Signal correction method for pulse terahertz system Technical Field The application relates to the technical field of terahertz waves, in particular to a signal correction method for a pulse terahertz system. Background Terahertz waves are electromagnetic waves with wavelengths between microwaves and infrared light, and have been widely used in the fields of communication technology, substance detection, imaging technology, and the like due to their unique frequency characteristics. The terahertz system mainly comprises a pulse terahertz system and a continuous wave terahertz system, and the main differences are that the forms of terahertz signals are different. In the pulse terahertz system, the time domain expression form of the terahertz signal is a periodic pulse signal, the frequency domain expression form is a broadband frequency spectrum, the frequency range of the terahertz signal can generally cover a plurality of THz, and the system generally converts femtosecond laser pulses into terahertz waves through the forms of photoconductive antennas, electro-optic crystals and the like. In a continuous wave terahertz system, a time domain expression form of a terahertz signal is a periodic continuous signal (the most common form is a sine signal), a frequency domain expression form is usually a single frequency point, and terahertz generation and detection are generally realized by using a quantum cascade laser, electronic frequency conversion and other modes. The pulse terahertz system is generally composed of a terahertz generator, a terahertz detector, an excitation module and a signal acquisition module. The terahertz generator generates a terahertz pulse signal under the action of the excitation module, and then transmits the terahertz pulse signal to the terahertz detector in an air feed (space radiation) or path feed (transmission line and waveguide) mode, and the terahertz detector converts the signal into a current or voltage signal and transmits the current or voltage signal to the signal acquisition module after receiving the terahertz pulse signal. However, in the terahertz signal transmission process, various inherent influences in the terahertz system can cause disturbance to signals of the pulse terahertz system, such as a fabry-perot effect of a terahertz lens during terahertz space-feed transmission, absorption and dispersion of materials in a transmission path, processing errors of a transmission line during terahertz space-feed transmission, transmission coupling mismatch and the like. These inherent effects are difficult to cancel by repeated experiments and can also introduce unpredictable distortions to the real signal. Disclosure of Invention The application aims to provide a signal correction method for a pulse terahertz system, which is used for solving the problems of high cost and easy signal distortion caused by system inherent influence elimination in the current pulse terahertz system. In order to achieve the above purpose, the application adopts the following technical scheme: The application provides a signal correction method for a pulse terahertz system, which comprises the following steps: Measuring a terahertz waveform of a terahertz generator in a pulse terahertz system by using a terahertz waveform standard device, and carrying out Fourier transform on the time domain waveform to obtain a frequency spectrum F ref of the time domain waveform; in a pulse terahertz system, a terahertz detector in the pulse terahertz system is used for measuring a terahertz signal generated by a terahertz generator, and a time domain waveform of the measured terahertz waveform is subjected to Fourier transform to obtain a frequency spectrum F out of the time domain waveform; Calculating a distortion coefficient D (F), wherein the calculation formula is D (F) = (F out-Fref)/Fref; When the pulse terahertz system is used again, the frequency spectrum F 1 of the terahertz signal generated by the terahertz generator is measured by using the terahertz detector inside the pulse terahertz system, the frequency spectrum of the terahertz signal after correction is F real(f)＝F1/(1+D (F)), and the corrected terahertz signal frequency spectrum can be obtained through inverse Fourier transformation, so that the corrected terahertz time-domain waveform F real (t). Based on the technical scheme, the application can obtain the following technical effects: And calculating a distortion coefficient after obtaining frequency spectrum data of the terahertz signal through the terahertz waveform standard device, correcting frequency domain data of the terahertz signal obtained in the terahertz system through the distortion coefficient, and obtaining a distortion-free terahertz time domain waveform through inverse Fourier transform. Therefore, no additional hardware design is needed, the cost is low, and the terahertz generator in the system can be used for a long time only by sending the terahertz generator to t