Generation of high-average-power ultrabroad-band infrared pulses

摘要

This paper summarizes the results of analytical and numericalnstudies on a novel technique that is capable of providing high averagenpower ultra broadband radiation that extends from approximately 2 to 16nΜm. Such a spectrum has several potential applications, includingntelecommunications and remote sensing. Additional attractive features ofnthe new source are its anticipated compact size, light weight,nruggedness, and affordable cost. The technique is based on theninteraction of a beat wave with a nonlinear medium. The beat wave isnformed from the mixing of two CO2 laser beams with closelynspaced wavelengths, such as 9.5 and 9.6 Μm. The discretenultrabroad-band spectrum is generated in a nonlinear optical medium bynthe self-phase modulation process, a third-order nonlinearity. Thenlong-wavelength portion of the spectrum, i.e., from 5 to 16 Μm isnproduced directly from the interaction of the beat wave with a GaAsncrystal. The short-wavelength portion of the spectrum is produced fromnthe interaction of a frequency-doubled beat wave with a GaAs crystalnfollowing the chirping of the pulse by a different GaAs crystal and itsnsubsequent optimal compression by a thin sapphire slab