Process of Near Infrared Radiation Generation via Optical Rectification of a Few Optical Cycles Laser Pulse in LiNbO3 and Filtration by Fibre-Bragg Grating
David L. Hovhannisyan and Alexander O. Vardanyan
In this paper we study the generation of near infrared radiation in the wavelength range (3–5) µm, which occurs during the propagation of an extraordinary linearly polarised laser pulse lasting a few optical cycles in the direction normal to the optical axis of a nonlinear uniaxial crystal with the 3 symmetry group. We describe the propagation of the laser pulse by solving Maxwell’s equations using the FDTD method. As an example, we calculate the spectrum profile of near infrared radiation generated during the propagation of a laser pump pulse with a duration 10 fs at a wavelength of 850 nm. We apply our model to study the propagation of a femtosecond laser pulse in a LiNbO 3 crystal of 375 µmthickness. We study the filtration of the near infrared radiation at the 3 8 µmcentral wavelength by the fibre-Bragg grating. The results obtained may be used in designing femtosecond tunable laser sources in the IR range.