RESUMO
We propose using cross-correlation frequency-resolved optical gating for dispersion characterization of optical elements with high dispersion, such as ultrashort pulse stretchers and compressors. The technique is based on spectrally resolved second-order cross correlation (sum frequency generation) of a stretched pulse with a reference short pulse. Dispersion of optical elements with a high pulse stretching ratio can be completely characterized using this method, even with moderate resolution of spectral measurements of the cross-correlation signal. The proposed technique is used to measure dispersion of a chirped Bragg grating recorded in photo-thermo-refractive glass. It was found that dispersion of these gratings is almost linear with wavelength and has approximately the same slope with opposite signs for two orientations of the grating with opposite faces of the grating used as the input face. Analysis of higher-order dispersion of the grating shows some variations of dispersion across the aperture of the grating, mostly in the amount of third-order dispersion contribution.
RESUMO
We demonstrate a novel technique for locking and tuning of a near-degenerate nanosecond optical parametric oscillator (OPO) using a transversely chirped volume Bragg grating. When the grating was translated, the OPO signal wavelength could be tuned from 1011 to 1023 nm (3.5 THz). The OPO was based on a periodically poled KTiOPO(4) as a nonlinear crystal and was pumped at 532 nm with up to 1.9 mJ of energy. The generated signal at an energy of 0.37 mJ had a bandwidth of 0.50 nm and a suppression of broadband background of >30 dB. The demonstrated technique is widely applicable for the construction of narrowband tunable sources.