Diffractive optical isolator made of high-efficiency dielectric gratings only.
The working principle of an optical isolator made of two corrugated dielectric gratings is introduced. One grating acts as a polarizer, and the other acts as a quarter-wave plate used in conical incidence converting linearly polarized light into circularly polarized light. Global maxima of diffraction efficiency for surface-corrugated gratings with binary, sinusoidal, and pyramidal ridge shapes with dependence on the material index are identified. Regarding technological feasibility for use in the visible wavelength range, high-frequency gratings with a binary shape were realized. With these gratings, an extinction ratio of more than 40 dB for the polarizer is theoretically possible, and more than 20 dB was experimentally achieved. A good correlation between theoretically calculated efficiencies and birefringences based on rigorous methods and the experimental results is demonstrated.
Glaser
Tilman
T
Institute for Physical High Technology, Jena, Germany. glaser@ipht-jena.de
Schröter
Siegmund
S
Bartelt
Hartmut
H
Fuchs
Hans-Jörg
HJ
Kley
Ernst-Bernhard
EB