THEORETICAL STUDY OF OPTICAL CAVITIES.

A theoretical study is performed of the resonant modes of a laser cavity having end mirrors with periodic reflectivity. Two particular examples are examined the case of end mirrors constituted by two identical strip diffraction gratings, and the case of end mirrors constituted by definite-ruling phase gratings. In the first example the modes and the corresponding eigenvalues are evaluated in successive approximations. It is found that a particular frequency exists for which losses are very low, while neighboring frequencies suffer heavy losses. This effect increases very rapidly with the total number of strips in the grating. In the case of phase gratings at transverse resonance the problem can be reduced to that of a resonator terminated by strip gratings. Author