Upconversion of Broadband Infrared Radiation into Visible Light for Different Pumping Parameters

Abstract

The influence of pump radiation parameters such as the polarization and the spectral width of infrared radiation on the conversion of broadband radiation in lithium niobate crystals was investigated. The spectra of converted radiation were calculated for two types of phase matching in the negative uniaxial crystal by taking into account the convergence of the light beam in the crystal. Experimental spectra were obtained and compared with the calculated spectra.

Change in the structural imperfection of lithium niobate crystals doped with zinc

“…When a divergent beam of broadband IR radiation propagates through a nonlinear optical crystal in the phase matching direction, the second harmonic of one of the input frequencies and sum frequencies is generated [14][15][16][17]. The phase matching conditions under nonlinear optical interaction are determined by the dependence of refractive indices on the R ratio in LiNbO 3 crystal.…”

“…The width of the converted radiation spectrum depends to a great extent on the type of crystal used, its thickness, type of interaction (phase matching), and the position of the phase matching frequency in the spectrum of broadband IR radiation [14][15][16][17][18]. Con verted radiation has a maximum spectral width when the 90° phase matching frequency (ω 0 ) is chosen exactly in the middle of the frequency range of the incident IR radiation.…”

“…The amplified signal was digitized and sup plied to a computer. The errors in determining the radiation wavelength and signal intensity were, respec tively, Δλ = ±0.5 nm and ΔI = 5% [14,15].…”