Abstract: An optical device is presented comprising: a cavity defining a cavity axis of light propagation; at least two optical elements having their optical axes, respectively, and being aligned along said cavity axis such that the optical axes of the optical elements coincide with said cavity axis; and a positioning unit associated with at least one of said at least two optical elements. The positioning unit is configured and operable for providing controllable axial rotation of said at least one optical element about the cavity axis, thereby enabling controllable fine adjustment of orientation of said at least one optical element relative to the at least one other optical element, while keeping the aligned positions of the optical elements with respect to said cavity axis.

Abstract: An optical device is presented comprising: a cavity defining a cavity axis of light propagation; at least two optical elements having their optical axes, respectively, and being aligned along said cavity axis such that the optical axes of the optical elements coincide with said cavity axis; and a positioning unit associated with at least one of said at least two optical elements. The positioning unit is configured and operable for providing controllable axial rotation of said at least one optical element about the cavity axis, thereby enabling controllable fine adjustment of orientation of said at least one optical element relative to the at least one other optical element, while keeping the aligned positions of the optical elements with respect to said cavity axis.

Abstract: A method of fabricating an invertedly poled domain structure having alternating sections of opposite electric polarities, from a ferroelectric crystal wafer (1) having two opposite polar surfaces, comprises patterning at least one of the two polar surfaces of the wafer to comprise a plurality of alternating discrete regions, of which first regions are adapted for and second regions are protected from the direct application thereto of an electric contact; applying to both polar surfaces of the wafer electrically conducting electrodes (10 and 11) so that the first regions are in direct contact with the electrodes and the second regions are protected from such a contact; and applying to the electrodes an electrical field (20) of the intensity E. The electrical field is applied to the wafer at a working temperature by heater/cooler (15).