Second harmonic generation was observed in N-doped H : SiO2 films after poling under x-ray irradiation from a synchrotron at room temperature. The measurements of the photocurrent confirmed that the vitreous films have been poled. The magnitude of the induced second-order nonlinear coefficients measured from the Maker fringe is in the order of 0.001 pm V−1. This provides direct evidence that poling under x-ray irradiation is achievable at room temperature in amorphous materials.

Second harmonic generation in N-doped H : SiO2 films by poling under x-ray irradiation

Gamma-ray radiation effect on the non-resonant third-order optical nonlinearity of the germano-silicate optical fiber has been investigated by the continuous-wave self-phase modulation method. The nonlinear refractive index, ${{\rm n}_2}$ , of the gamma-ray irradiated optical fiber was found to increase linearly with the increase of the gamma-ray induced absorption. The increased ${{\rm n}_2}$ has been mainly ascribed to the NBOs and Ge-realted radiation-induced defects having hyperpolarizabilities.

Gamma-Ray Radiation Effect on Non-Resonant Third-Order Optical Nonlinearity of Germano-Silicate Optical Fiber

Gamma-ray-irradiated lead-silicate glass shows enhanced photoinduced quasi-phase-matched second-harmonic generation This is due to the formation of color centers, which serve as traps for space charge, resulting in an internal dc field due to the coherent photovoltaic effect The color center formation also enhances the χ(3) nonlinearity, which contributes to the photoinduced quasi-phase-matched second-harmonic generation as well We separate these two contributions and show their respective roles

Optical nonlinearity in gamma-ray-irradiated lead-silicate glass

Enhanced χ(3) in γ-ray irradiated bulk glass

Gamma-ray-irradiated light-flint silicate bulk glass (Schott Glass LF5), which contains a large amount of lead oxide, displays enhanced photoinduced quasi-phase-matched second-harmonic generation (PSHG), whereas nonirradiated glass under the same experimental conditions does not generate this nonlinear effect. The dependence of the efficiency of PSHG on the amount of gamma radiation (up to 530 krad) is experimentally studied, as is the role of thermal recovery (bleaching) of the color centers as a result of seeding with the second harmonic. The effect of long-term fading is studied with a sample that was irradiated 8 years ago. Gamma irradiation of boron-crown silicate glass (BK7) does not show this enhancement.

Lea Boehm

Papers

Enhanced χ(3) in γ-ray irradiated bulk glass

Enhanced photoinduced χ (2) in gamma-ray-irradiated bulk glass