| THz wave, with some characteristics because of its unique electromagnetic spectrum location, has a widespread application prospect on the field of civilization and military. At present, an important aspect of THz research is mainly concentrated on THz sources. Difference frequency generation (DFG) of THz waves based on nonlinear crystals is obtained from two coherence laser beams whose wavelength are so close and focused on a nonlinear crystal to mix frequency. But the dual-wavelength source with two pump light sources, has disadvantages of the overlarge pump volume, operating complex, etc. Using the dual-wavelength optical fiber laser as a simple pump light source will be an effective way to produce THz wave.This paper constructed a complete set of DFG experiment system by using linear-cavity double wavelength erbium-doped fiber laser, and studied the related features. Experiment proves that the device is low cost, structure compact, easy tuning and working at room temperature. This will bring terahertz source technology provides effective reference value.Main contributions of the paper are as follows:(1) A theoretical model of three waves interact wave vector in nonlinear medium is studied and THZ wave radiation conditions is deduced. Terahertz wave radiation based on QPM is analyzed with related features in detail.(2) Based on difference frequency generation of THz waves radiation and the laboratory conditions, a new linear-cavity double wavelength erbium-doped fiber laser near1550nm is designed. And stable laser output is obtained with the narrow line width, single longitudinal mode by some experiments.(3) Combined with physicochemical properties of periodically poled Mg-doped lithium niobate (PPMgLN), a complete set of DFG experiment system is constructed by using linear-cavity double wavelength erbium-doped fiber laser. And tunable THZ continuous wave up to1THZ can be obtained. Tuning characteristics are also analyzed. |
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