Terahertz wave generator

A terahertz wave generator, comprising:

• a source of an electromagnetic wave for outputting a first electromagnetic wave;
• a diffraction element for diffracting the first electromagnetic wave;
• an optical system for transmitting the first electromagnetic wave diffracted by the diffraction element;
• and,
• a nonlinear optical crystal for generating a second electromagnetic wave with irradiation of the first electromagnetic wave transmitted by the optical system, wherein
• the second electromagnetic wave is a terahertz wave in a pulse form;
• the first electromagnetic wave is an electromagnetic wave in a pulse form having shorter wavelength than that of the terahertz wave;
• a pulse front of the first electromagnetic wave is tilted within the nonlinear optical crystal such that the first electromagnetic wave satisfies a phase matching condition for generating the second electromagnetic wave within the nonlinear optical crystal by a nonlinear optical effect;
• at least a part of a plane optically conjugated to a diffractive plane of the diffraction element is formed in the nonlinear optical crystal;
• and,
• the diffraction element, the optical system and the nonlinear optical crystal are configured such that a direction normal to the conjugated plane in the nonlinear optical crystal and a direction normal to a plane formed by the pulse front of the first electromagnetic wave in the nonlinear optical crystal are matched with each other.