Application of Optical Kerr Gate with SrTiO₃ Crystal in Acquisition of Gated Spectra from a Supercontinuum

We investigate the optical Kerr effect of SrTiO₃ (STO) crystal, of which the nonlinear response time was measured to be less than 200 fs, while the nonlinear refractive index is estimated to be 2.16×10^-15 cm²/W. Using the optical Kerr gate (OKG) technique with an STO crystal as the Kerr medium, we obtain narrow-bandwidth and symmetric gated spectra from a supercontinuum generated in distilled water by a femtosecond laser. The experimental results show superiority compared with the gated spectra obtained using OKG with CS₂ as the Kerr medium, demonstrating that STO crystal is a promising OKG medium.