An
evanescent wave is a nearfield standing wave exhibiting exponential decay
with distance. Evanescent waves are always associated with matter, and are
most intense within one-third wavelength
from any acoustic, optical,
or electromagnetic transducer.
Optical
evanescent waves are commonly found during total internal reflection.
Monotonically
decaying wave formed when an electromagnetic wave is reflected off an interface between two different transparent dielectrics
at an angle greater than the critical angle so that total internal reflection
occurs; typically coupled to an electeromagnetic mode (standing wave) inside
a waveguide
