Fig. 4: Simulated propagation of Boyer-Wolf Gaussian modes in the 2:1 anisotropic laser cavity and in a 2:1 anisotropic GRIN medium.

a Left, amplitude of the transverse mode of the laser cavity at the output coupler. Right, \(x\) and \(y\)-cross sections of a full round-trip propagation of the lasing mode inside the resonator cavity. The \(y\)-cylindrical mirror and the output flat mirror create a single cavity in the \(y\)-axis. While the \(x\)-cylindrical lens at the middle of the resonator creates two cavities, one with the flat mirror and one with the \(y\)-cylindrical mirror, as one can clearly observe from the propagation cross-sections. b Propagation of a Boyer-Wolf Gaussian mode in an anisotropic 2:1 GRIN medium. The Boyer-Wolf Gaussian modes are eigenmodes of such a GRIN medium and therefore propagate without diffraction. c Transmutation of the Boyer-Wolf Gaussian beams to a Weber parabolic nondiffracting beams. The metamorphosis takes place when the order, \(n\), and the waist size, \({w}_{0}\), tend towards infinity, while maintaining the ratio \({k}_{t}=2n/{w}_{0}\) constant, which becomes the transverse wavevector of the nondiffractive beam.