Lasing modes in equilateral-triangular laser cavities

We report the study of lasing modes in broad-area, equilateral-triangular laser cavities. An alternative approach is proposed to study optical modes in equilateral triangular cavities in an analytical form. The modes were obtained by examining the simplest optical paths inside the cavity, which yields the final solution with the boundary conditions. The cavities can be fabricated from semiconductor heterostructures grown on ~111!oriented substrates, which can be easily cleaved into equilateral triangular shapes. Such a design takes advantage of total internal reflection at the cleaved facets of the cavity for circulating modes. Experimental results are obtained from cavities fabricated from a superlattice structure of In0.13Ga0.87As/GaAs grown on a ~111! GaAs substrate.