  The concept of the PT-symmetry, originating from the quantum field theory,
has been intensively investigated in optics, stimulated by the similarity
between the Schr\"odinger equation and the paraxial wave equation that governs
the propagation of light in a guiding structure. We go beyond the bounds of the
paraxial approximation and demonstrate, using the solution of the Maxwell's
equations for light beams propagating in deeply subwavelength waveguides and
periodic lattices with "balanced" gain and loss, that the PT symmetry may stay
unbroken in this setting. Moreover, the PT-symmetry in subwavelength optical
structures may be restored after being initially broken upon the increase of
gain and loss. Critical gain/loss levels, at which the breakup and subsequent
restoration of the PT symmetry occur, strongly depend on the scale of the
structure.

Optics;Pattern Formation and Solitons