Application of optical Kerr gate with SrTiO ₃ crystal in acquisition of gated spectra from a supercontinuum

We investigate the optical Kerr effect of SrTiO ₃ (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 cm ²/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 CS ₂ as the Kerr medium, demonstrating that STO crystal is a promising OKG medium.