  Wave tunneling is an intriguing phenomenon spanning different branches of
physics, from quantum mechanics to classical electrodynamics and optics. The
Wigner (or phase) time is proved to be an adequate measure to describe wave
transit through a potential barrier or material layer in the tunneling regime.
Here, we analytically and numerically calculate the Wigner time for
electromagnetic-radiation propagation through the layer of both lossless and
lossy plasmas. It is shown that the plasma frequency is the key parameter
governing the value of Wigner time allowing us to interpret tunneling as due to
the reaction of plasma as a whole. We analyze the Wigner time for obliquely
incident waves of TE and TM polarizations and discuss the meaning of negative
Wigner times appearing in the lossy case in the low-frequency range and close
to the plasma frequency. The results show that plasma deserves attention as a
perspective object for tunneling studies.
