Akademik Veri Yönetim Sistemi
PHYSICAL REVIEW B, cilt.97, 2018 (SCI-Expanded)
Based on operations prescribed under the paradigm of complex transformation optics (CTO) [F. Teixeira and W. Chew, J. Electromagn. Waves Appl. 13, 665 (1999); F. L. Teixeira andW. C. Chew, Int. J. Numer. Model. 13, 441 (2000); H. Odabasi, F. L. Teixeira, and W. C. Chew, J. Opt. Soc. Am. B 28, 1317 (2011); B.-I. Popa and S. A. Cummer, Phys. Rev. A 84, 063837 (2011)], it was recently shown in [G. Castaldi, S. Savoia, V. Galdi, A. Alu, and N. Engheta, Phys. Rev. Lett. 110, 173901 (2013)] that a complex source point (CSP) can be mimicked by parity-time (PT) transformationmedia. Such coordinate transformation has amirror symmetry for the imaginary part, and results in a balanced loss/gain metamaterial slab. A CSP produces a Gaussian beam and, consequently, a point source placed at the center of such a metamaterial slab produces a Gaussian beam propagating away from the slab. Here, we extend the CTO analysis to nonsymmetric complex coordinate transformations as put forth in [S. Savoia, G. Castaldi, and V. Galdi, J. Opt. 18, 044027 (2016)] and verify that, by using simply a (homogeneous) doubly anisotropic gain-media metamaterial slab, one can still mimic a CSP and produce Gaussian beam. In addition, we show that a Gaussian-like beams can be produced by point sources placed outside the slab as well. By making use of the extra degrees of freedom (the real and imaginary parts of the coordinate transformation) provided by CTO, the near-zero requirement on the real part of the resulting constitutive parameters can be relaxed to facilitate potential realization of Gaussian-like beams. We illustrate how beam properties such as peak amplitude andwaist location can be controlled by a proper choice of (complex-valued) CTOJacobian elements. In particular, the beam waist location may be moved bidirectionally by allowing for negative entries in the Jacobian (equivalent to inducing negative refraction effects). These results are then interpreted in light of the ensuing CSP location.