Abstract: A slab waveguide laser which provides efficient operation in predominantly a single mode operation includes a periodic modulation structure positioned between a slab waveguide and one of two cavity mirror reflectors. Alternatively, the periodic modulation structure may be included along the slab face. The periodicity of the periodic modulation structure is determined by the width of the waveguide to ensure that the periodic modulation is coherently self-imaged in one (or more) round trip(s) of the laser cavity. Because of the low loss propagation within the slab waveguide, overall cavity losses are minimized in both the lateral and transverse directions of the slab.

Abstract: A process for perforating a metal sheet with clean holes of substantially uniform size and shape comprises placing a suitable transparent backing tape, such as an adhesive polyethylene tape, on one surface of the metal sheet. The assembly is placed in a fixture, a laser beam generated by a pulsed Nd:YAG laser is impinged on the opposite surface of the metal sheet, and the laser parameters are chosen to control the laser beam to penetrate the metal sheet and form a plurality of small tapered holes therein without penetrating the tape. A clean metal surface results around the holes with no recast structure or dross present in and around the holes. A drilled titanium sheet of the above type is particularly suited for utility as an outer wing leading edge of an aircraft and which provides good laminar flow control efficiency.