Propagation of Gaussian beams in dielectric waveguides

The propagation of Gaussian beams in both a homogeneous medium and a lenslike medium is treated. The correct Helmholz equation derived by the author is used to obtain the analytic solutions, taking into account the diffraction effect. Based on this, the beamwidth and the form of the wavefront are considered. The beamwidth will increase monotonically in the homogeneous medium and will be sinusoidal in the lenslike medium; that is, in the lenslike medium, the width will alternately increase and decrease.<
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