External cavity enhanced difference frequency tunable single-frequency terahertz source
A terahertz radiation and difference frequency technology, applied in the terahertz field, can solve the problems of low coherent light mixing output power, narrow tuning range, and bulky free electron laser, so as to improve photon utilization efficiency and realize external cavity enhancement Effect
Inactive Publication Date: 2014-03-19
HFB PHOTONICS CO LTD
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[0004] However, free electron lasers are bulky and difficult to apply in practice. Although optically pumped gas lasers and return wave tubes have high output power, their tuning range is narrow, coherent optical mixing has low output power and narrow tuning range, and quantum cascade lasers need to operate at low temperatures. , and the defects such as narrow tuning range
In recent years, optical terahertz radiation sources based on optical nonlinear frequency down-conversion technology have made great progress, but due to the lack of high nonlinear coefficient terahertz difference-frequency crystals and high-efficiency pumping methods, their output power levels and tuning ranges still exist. Very limited, unable to fully meet the relevant applications of terahertz
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[0033] The present invention will be further described below with reference to the drawings and embodiments
[0034] figure 1 Shown is the relationship curve between the output THz frequency and the wavelength of the variable pump light obtained according to the energy conservation condition. Fixed one of the wavelengths λ 1 Unchanged (1.9 ), it can be calculated that when the output THz frequency is tuned at 0.5-5THz, the wavelength of another pumping light λ 2 The change curve. by figure 1 It can be seen that when the variable pump wavelength λ 2 From 1.906 Changes to 1.962 When, the tuning output of 0.5-5THz tuning can be realized.
[0035] figure 2 Shown is a schematic diagram of the quasi-phase matching crystal structure. The polarization direction of the pump light is 1. [1-11], and the light direction is 2. [110] crystal orientation. According to the quasi-phase matching condition, we can get that the pump wavelength is 1.9 When the first-order quasi-phase matching l...
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The invention discloses an external cavity enhanced difference frequency tunable single-frequency terahertz source based on a 2 micrometer single-frequency fiber laser pump. A 2 micrometer tunable single-frequency fiber laser is used as a pump source, a quasi-phase-matching periodic reversal GaAs crystal is used as a difference frequency crystal, an external cavity enhanced structure comprises a four-mirror ring resonant cavity, and single-frequency terahertz radiation output is realized. A single-frequency fiber laser output is coupled into the quasi-phase-matching GaAs crystal through a pump coupling system, pump light passes the crystal in a reciprocating manner by the aid of the four-mirror ring cavity structure, photon utilization efficiency is improved, so that an external cavity is enhanced, finally, terahertz waves are outputted by a terahertz radiation output mirror placed on the right side of the quasi-phase-matching crystal, and the terahertz source has the advantages of compact structure, high efficiency, high reliability and the like.
Description
Technical field [0001] The present invention belongs to the field of terahertz technology, especially a kind of Single-frequency fiber laser pumped external cavity enhanced difference frequency tunable single-frequency terahertz source. Background technique [0002] The terahertz band is located between microwaves and light waves, and contains a wealth of physical and chemical information when interacting with substances. Therefore, terahertz waves are widely used in basic research fields such as molecular spectroscopy and biological spectrum imaging analysis. Current terahertz spectroscopy imaging technology mainly uses ultra-short pulse excitation of photoconductors and nonlinear materials to obtain broadband terahertz radiation sources, but the output of terahertz waves excited by ultra-short pulse lasers is due to broadband spectrum and other reasons, and its spectral resolution has great Limitations. The current time-domain spectroscopy analysis system--TDS can only achieve...
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IPC IPC(8): H01S3/094H01S3/16H01S3/08
Inventor 史伟张卓
Owner HFB PHOTONICS CO LTD