Method and device for filtering away coherent noise of terahertz asynchronous scanning system

Abstract

The invention discloses a method and device for filtering away coherent noise of a terahertz asynchronous scanning system. Through twice 0:pi phase modulation on the terahertz signals and the once 0:pi phase modulation on coherent noise, terahertz signals are firstly changed into reverse phase signals sand are then changed into inphase signals; the coherent noise becomes opposite phase noise; through multi-time averaging, the coherent noise can be conveniently eliminated; the signal-noise ratio can be improved. An operation amplifier and a multipath complexing module are used for achieving theeffects of eliminating the coherent noise and improving the signal-noise ratio. The device has the advantages that the manufacturing cost is low; the performance is excellent; the solid foundation islaid for the further integration of an asynchronous high-speed scanning terahertz time domain spectral system.

Description

technical field [0001] The invention belongs to the technical field of THz, and in particular relates to a method and a device for filtering coherent noise of a terahertz asynchronous scanning system. Background technique [0002] Terahertz refers to electromagnetic radiation waves in the frequency range of 0.1THz to 10THz. This band is between microwave and light wave, and it is the intersection field of electronics and photonics. Due to the unique properties of transient, low energy and coherence, terahertz waves have great scientific value and broad application prospects in many fields such as nondestructive testing, wireless communication, military radar, biochemistry and so on. In recent years, many research groups have carried out research in the field of terahertz time-domain spectroscopy. Due to the characteristics of the frequency band to which the terahertz wave belongs, as well as the vibration and rotational energy levels of many biomolecules are located in thi...

AI Technical Summary

Problems solved by technology

[0005] 1) Using a mechanical delay device, due to the mechanical relaxation time of the motor, it will take a long time to scan all the points, so the traditional TDS system generally takes several to tens of minutes to obtain a terahertz time-domain spectrum. very long

[0006] 2) Since the mechanical translation stage uses a motor to generate motion, it will generate vibration when moving. This vibration will affect the optical path structure of the entire optical system, so it needs to be tested on an optical platform, which is not easy to integrate and is not conducive to Making a mobile and portable terahertz time-domain spectroscopy system

[0007] 3) If the construction of the translation platform is not accurate enough, the light beam will have a slight offset with the movement of the translation platform, which will further affect the experimental results

However, this kind of noise cannot be filtered out by multiple averages, thus limiting the improvement of the signal-to-noise ratio

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