We report an experimental observation of radiation-induced optical absorption in undoped congruent lithium niobate (LiNbO₃) crystals between the 190 nm and 3200 nm wavelength range. It was found that high-dose (up to 288 Gy) gamma rays did not significantly affect the optical absorption of LiNbO₃ during that wavelength range. However, upon the order of 10¹⁶ cm⁻² neutron irradiation, the change in the absorption coefficient was up to 0.6 cm⁻¹ at a wavelength of 532 nm and remained after 13 days in the dark at room temperature. The nonlinear optical performance was characterized by conducting third-order quasi-phase-matched second harmonic generation in neutron-irradiated periodically-poled LiNbO₃, showing that the phase-matching condition was altered, and the conversion efficiency was still comparable with a non-irradiated one.

We report a line-narrowed electro-optic periodically-poled-lithium-niobate (PPLN) Q-switched laser with intra-cavity optical parametric oscillation using a grazing-incidence grating, producing 8-ns, 5-\mu J pulses at 10-kHz repetition rate when pumped with a 10-W diode laser at 808 nm. The output wavelength is centered at 1554.3 nm with a 0.03-nm spectral width. Wavelength tuning is achieved by rotating a mirror and changing the crystal temperature.

We report a cascaded mode-locked Nd:YVO ₄ laser at 1064 nm with direct in-band pumping at 914 nm. A 25-mm-long MgO doped periodically-poled LiNbO ₃ crystal was used to produce mode-locked laser pulses. A volume Bragg grating was used to manipulate the output spectrum of the laser. In the positive Kerr-lens scheme, the output power was 3.81 W at 166.8-MHz repetition rate. In the negative Kerr-lens scheme, the output power was 4.81 W at 108.6-MHz repetition rate. Typical pulse duration and the full-width-at-half-maximum spectral width were 35 ps and 0.05 nm, respectively, yielding a time-bandwidth product of 0.5.

Electro-optic (EO) Bragg deflectors have been extensively used in a variety of applications. Recent developments show that bandwidths and deflection efficiencies, as well as angular bandwidths, would significantly limit the utilization of EO Bragg deflectors, especially for applications which need strong focusing, such as intra-cavity applications. In this paper, we introduce a broadband EO Bragg deflector based on periodically-poled lithium niobate with a monolithic dual-grating design. We analyzed the deflection properties of this device by using a modified coupled wave theory and showed that this device can be still efficient for a small beam radius under strong focusing, whereas a single-grating one becomes very inefficient. Using a 1064-nm laser beam with a 100-μm beam radius, we obtained a 74% deflection efficiency with a 190-V bias voltage with a 0.5-mm-thick and 7.5-mm-long dual-grating sample. The acceptance angle for the Bragg condition of this device is as large as a few tens of mrad. The potential bandwidth of this device exceeds 500 nm if the proper operation region is chosen.