Device and method for improving measurement stability of Terahertz parametric oscillation source

Abstract

The invention discloses a device and method for improving the measurement stability of a Terahertz parametric oscillation source. The device comprises a laser, a Terahertz parametric oscillator, a Terahertz detector, a Stokes light detector, a light-beam collector, a sample, a data acquisition card, a computer and a refractive-index gradient mirror, wherein the Terahertz parametric oscillator comprises a nonlinear crystal and a Stokes light resonance cavity; the laser generates pump light which is incident to the Terahertz parametric oscillator through the refractive-index gradient mirror, onepart of the pump light is collected by the light-beam collector, and the other part of the pump light generates Stokes light and Terahertz wave on the basis of the action of stimulated polariton scattering. The device and method disclosed by the invention have the beneficial effects that by utilization of the characteristic that the stability of the Stokes light is in direct proportion to the stability of the Terahertz in the Terahertz parametric process, and the Stokes light is used as reference light of the Terahertz wave, so that the measurement error caused by instability of the Terahertzparametric source can be eliminated.

Description

technical field [0001] The invention relates to the field of nonlinear optical frequency conversion, in particular to a device and method for improving the measurement stability of a terahertz parametric oscillation source based on Stokes light (Stokes) self-reference technology (Self-reference). Background technique [0002] Terahertz (Terahertz, referred to as THz, 1THz = 10 12 Hz) band refers to the frequency range from 100 GHz to 10 THz, the corresponding wavelength is from 3 mm to 30 microns, and the electromagnetic spectrum range is quite wide between millimeter wave and infrared light. Because this frequency band is the transition frequency band from macroelectronics to microphotonics, it has many unique properties. Terahertz radiation technology is one of the key core technologies in the development of science and technology in the THz field, especially THz coherent radiation sources with fast tuning, high power and high stability are widely used in life sciences, m...

AI Technical Summary

Problems solved by technology

However, due to the influence of pump laser energy fluctuations, Stokes optical resonator detuning, thermal effects of nonlinear crystals, and instability in the process of stimulated electromagnetic coupler scattering in actual experimental conditions, based on terahertz The RMS value of the terahertz wave energy stability output by the parametric process is usually large (greater than 15%), which is difficult to meet its practical application requirements in spectral detection and imaging

At present, in order to eliminate the influence of the instability of the terahertz parametric source in practical applications, the method of splitting the terahertz wave is usually used, and one of the beams is used as a reference light to correct the probe light due to the instability of the terahertz source. However, this traditional method of eliminating light source instability can only maintain a high signal-to-noise ratio when the terahertz wave power required for measurement is relatively low and the sample absorbs the terahertz wave less. Greatly limit the practical application of terahertz wave parametric source

For example, in the field of life sciences where terahertz waves are widely used, since the vibration and rotation frequencies of many biological macromolecules are in the terahertz band, biological tissues have strong absorption in terahertz waves. Hertzian waves perform spectral measurement or imaging of biological tissues. It is difficult to ensure that the probe light has high power to achieve high signal-to-noise ratio measurement by using the traditional method of eliminating the instability of the light source.

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