Generation of ultrashort pulses of millimeter and centimeter radiation in a waveguide partly filled with a nonlinear crystal

An experimental study was made of the generation of ultrashort pulses of wavelengths in the range 2–46 mm using a waveguide partly filled with a nonlinear crystal of LiNbO₃. These pulses were generated because of a nonlinear interaction (subtraction) of spectral components of radiation emitted by a picosecond neodymium laser. A numerical calculation was made of the coefficient representing delay of the emission of the difference frequency, of the thickness of the crystal, and its position relative to a wide waveguide wall. In addition to the H₀₁ wave, it was found that waves representing higher modes H_0m were also generated.