Patent ID: 7599409

Claim:
An electromagnetic wave generator comprising: a first pump beam emitter including a first pump source implemented by a first Cr-doped forsterite laser, configured to emit a first pump beam having a wavelength larger than one micrometer; a second pump beam emitter including a second pump source implemented by a second Cr-doped forsterite laser, configured to emit a wavelength-tunable second pump beam having a wavelength larger than one micrometer, the wavelength of which is different from the wavelength of the first pump beam; a nonlinear optical crystal having an electromagnetic wave exit face, configured to generate an electromagnetic wave of a difference frequency between the first and second pump beams and to emit the electromagnetic wave from the electromagnetic wave exit face; an optical system configured to irradiate the first and second pump beams to the nonlinear optical crystal, by adjusting an external intersection angle between the first and second pump beams within 0.5° at the difference frequency of 1 THz, and an angle control mechanism configured to rotate the nonlinear optical crystal so as to control an angle of the electromagnetic wave exit face against an optical axis of the first pump beam, wherein a frequency-tunable terahertz electromagnetic wave, tunable over a wide frequency band spanning from 0.5 to 7 THz, is emitted from the electromagnetic wave exit face, by changing the frequency of the second pump beam, being linked with the change of the external intersection angle and the change of the angle of the electromagnetic wave exit face.