| 摘要 |
An electromagnetic wave generator encompasses a first pump beam emitter ( 2 ) configured to emit a first pump beam (hv<SUB>1</SUB>) having a wavelength larger than one micrometer; a second pump beam emitter ( 25 ) configured to emit a wavelength-tunable second pump beam (hv<SUB>2</SUB>) having a wavelength larger than one micrometer, the wavelength of which is different from the wavelength of the first pump beam (hv<SUB>1</SUB>); a nonlinear optical crystal ( 19 ) configured to generate an electromagnetic wave (hv<SUB>3</SUB>) of a difference frequency between the first pump beam (hv<SUB>1</SUB>) and second pump beam (hv<SUB>2</SUB>); and an optical system (M<SUB>1</SUB>, M<SUB>2</SUB> , 18 ) configured to irradiate the first pump beam (hv<SUB>1</SUB>) and second pump beam (hv<SUB>2</SUB>) to the nonlinear optical crystal ( 19 ), by adjusting an external intersection angle between the first pump beam (hv<SUB>1</SUB>) and second pump beam (hv<SUB>2</SUB>) within 0.5° at the difference frequency of 1 THz. Here, a frequency-tunable terahertz electromagnetic wave (hv<SUB>3</SUB>) is generated in the nonlinear optical crystal ( 19 ), by changing the frequency of the second pump beam (hv<SUB>2</SUB>), being liked with the change of the external intersection angle.
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