Abstract: A light emitting element comprising diamond which contains N-V color centers in a maximum optical density of of 0.01 to 3.5 in a direction of excitation light, Ib type nitrogen atoms in a maximum optical density not larger than 0.2 in a wavelength range of 530 to 610 nm and optionally H3 color centers, which element can be efficiently produced from artificial diamond by a combination of irradiation by an electron beam or a neutron beam and annealing.

Abstract: A laser or other source of radiant electromagnetic energy removes optically transparent material (e.g., LiNbO.sub.3) to form various structures. To enhance coupling the radiant energy to the optical material, a layer of an ablative absorber (e.g., a metal or organic material) can be used. Alternately, the radiant source can be initially operated above a threshold that causes removal of a surface layer of the optical material. After selectively thus removing a surface layer of the optical material, subsequent sub-threshold applications of radiant energy remove additional optical material due to a change in the underlying material, rendering it more absorptive at the wavelength of the electromagnetic energy. Optical devices, including waveguides, can be formed, as well as isolation grooves, alignment structures, etc.