<title>Detailed study of plane-plane cavity fundamental mode far-field structure</title>

Simple waveguide model of arbitrary filled plane-plane cavity

“…The detection of structural anomalies in the far field of the single-mode Nd + : glass laser with plane mirrors and intracavity slit [2,3] gave the cause for the present article. Though these anomalies had obviously regular character, which had not been connected with the action of random factors, any explanation within the limits of existing theoretical conceptions [1,4,5] was not found.…”

“…We shall consider for the definiteness the cavity with a slit aperture, located at one of mirrors. This cavity is similar to that used in the experiments mentioned in the introduction [2,3]. Its optical scheme is completely equivalent to the cavity with one strip mirror and unlimited another one (Fig.…”

On problem of the rigorous diffraction quantitative description

“…As it was eventually found, the required field distribution at the slit can be composed as the sum of two components (Fig. 5), namely the diffracting wave itself and π phase shifted wave, the most part of the power of which is concentrated in a pair of separate peaks, which are clasped to the edges of a slit [13]. For the shape and height of the peaks shown in Fig.…”

“…However, as careful measurements show, the indicated correspondence is fulfilled precisely only for the plane wave diffraction. With the deviation of the amplitude distribution of a plane (quasi-plane) wave at the aperture from homogeneous one, the resulting Fourier-transform more and more differs from the real far field pattern [13].…”

“…For definiteness we shall consider such particular characteristic of this field as angular distribution of its minima. If one accepts as the initial reference point, the equidistant sequence of diffraction minima formed by the plane wave, and calculates the individual shifts of these minima after the replacement of the plane wave by an arbitrary non-uniform wave with the plane front, the common regularity arises [13]: the absolute shift of minima always decreases with moving from the center of the distribution (Fig. 4).…”