Zero infrared reflectance anomaly in doped silicon lamellar gratings. III. Electric field phase and energy flux distributions across the grating profile

Spatial (in-depth by lateral) electric field phase and Poynting vector distributions inside zero-reflectance binary lamellar gratings in variously doped n-Si irradiated by a normally incident TE polarized plane electromagnetic wave of wavelength 10.6 μm are studied. The electric field phase distribution surfaces for such gratings in dielectric-like Si up to the uppermost lossy case appear to have a channel with abrupt vertical walls formed by π to -π jumps of the electric field phase. For the gratings in metallic-like Si it is shown that the normal component of the Poynting vector vanishing in the grating line achieves a relatively large (as compared to a grating with the same doping but a high reflectance) negative value in the grating groove center. Such a flux confinement supports the idea of a cavity-resonance nature of the total absorption.