Abstract

A novel structure for coupled arrays of rf excited strip waveguide CO₂ lasers has yielded a single-lobe diffraction-limited far-field power distribution. In this new structure, the regions separating the array elements do not have enough optical gain to support laser oscillations, so the array is separated into individual strip waveguide channels that are coupled through the leaking of radiation into each other. Also, these regions do not introduce much loss to the in-phase locked super mode; thus the oscillating array mode is the one in which the fundamental waveguide modes in all channels are strongly locked in-phase. The structure is all metal and is easy to fabricate, and it uses the simple Fabry-Perot resonator. The strong locking between the elements, reflecting a wide locking range, translates itself into a generous tolerance to the geometry of the individual waveguides in the array. Two- and five-element arrays have been tested and both gave stable in-phase locked fundamental modes. The near-field and far-field power distributions have been measured, and the preliminary results show that the far-field center lobe has a diffraction-limited power distribution characteristic of the dimension of the array.

© 1991 Optical Society of America