Fiber-coupled terahertz photoconductive antenna detector based on optical frequency multiplication

Abstract

The invention belongs to the technical field of terahertz spectroscopy and imaging and relates to a fiber-coupled terahertz photoconductive antenna detector based on optical frequency multiplication,mainly comprising a fiber coupling module, an optical frequency multiplication module and a photoconductive antenna, wherein the fiber coupling module mainly comprises a fiber collimator and a focusing lens; the fiber collimator is located to the left side of the focusing lens; the fiber collimator and the focusing lens are as close as possible and have a distance range which is generally set as 0to 10 mm; the detecting light successively passes through the fiber collimator and the focusing lens from the left side of the fiber collimator and reaches the optical frequency multiplication module; the optical frequency multiplication module is disposed to the right side of the focusing lens; the photoconductive antenna is disposed to the right side of the optical frequency multiplication module; and the detecting light is transmitted through the optical frequency multiplication module to the photoconductive antenna. The fiber-coupled terahertz photoconductive antenna detector based on optical frequency multiplication is simple in overall structure, ingenious in design concept, low in preparation cost, suitable for industrial production, friendly in application environment, and extremely broad in market prospect.

Description

Technical field: [0001] The invention belongs to the technical field of terahertz spectroscopy and imaging, and relates to a terahertz photoconductive antenna detector, in particular to a fiber-coupled terahertz photoconductive antenna detector based on optical frequency doubling, which has low preparation cost and is used for terahertz spectroscopy and high imaging stability. Background technique: [0002] Terahertz wave refers to the frequency of 0.1 ~ 10THz (1THz = 10 12 Hz) electromagnetic waves, located between the microwave and infrared bands. It has the advantages of strong penetrating ability, low photon energy, and fingerprint spectrum, which makes it have extremely important application prospects in the fields of material identification, safety inspection, non-destructive testing of materials and structures, biopsy of biological tissues, and wireless communication. For broadband terahertz time-domain pulses, photoconductive sampling is one of the most effective d...

AI Technical Summary

Problems solved by technology

[0003] At present, there are two main types of relatively mature terahertz photoconductive antenna detectors: one is a fiber-coupled terahertz photoconductive antenna detector excited by a femtosecond laser with a wavelength of 1560nm (±40nm), and the performance of the femtosecond laser in the 1560nm band is stable. , the structure is compact, and this band can be transmitted by all optical fibers, the reliability and stability of the optical path are very high, but its disadvantage is that the semiconductor material corresponding to the wavelength of 1560nm is usually InGaAs, which is difficult to grow and the preparation process is complicated; One is a terahertz photoconductive antenna detector excited by a femtosecond laser with a wavelength of 780nm (±20nm). The semiconductor material corresponding to the wavelength of 780nm is usually GaAs or LT-GaAs grown at low temperature. These two materials are relatively simple to prepare , the cost is also relatively low, but there is the defect that the optical fiber technology in this band is not mature enough, and it cannot be conducted by optical fiber, and it is generally a free space system, so the stability and reliability of the optical path are poor, and it is greatly affected by the environment. The requirements of the use scene are relatively strict

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