Two-dimensional rectangular lattice distributed feedback lasers: A coupled-mode analysis of TE guided modes

Two-dimensional rectangular lattice distributed feedback lasers in a waveguide geometry are described by a coupled-mode analysis of a scalar wave equation derived from a vector field for TE guided modes. A detailed analysis is provided for a two-dimensional grating which allows the method of separation of variables for the scalar wave equation so that the threshold conditions are described by those of two orthogonal one-dimensional gratings. We present the correct definitions of threshold gain and detuning of the two-dimensional distributed feedback laser, and also the optimum design conditions for the minimization of the threshold gain. It is found that there is an optimum structural angle for the given area and periods of the two-dimensional grating.<
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