A SIMPLE RELATIONSHIP BETWEEN DIRECTIVITY AND LINEWIDTH OF A PLANAR MICROCAVITY LASER

On the basis of the analysis of the cavity quasimode structure, the relationship between the directivity and the linewidth of the output beam from a laser with a planar microcavity is examined assuming a narrow spectral width of the laser medium. A simple relation is obtained which implies that, in a planar laser, the directivity is determined by the net loss of the laser similarly to the laser linewidth.