Broadband antireflective structures applied to high resistive float zone silicon in the THz spectral range.
The optimal structural parameters for an antireflective structure in high resistive float zone silicon are deduced for a rectangular and a hexagonal structure. For this the dependence of the effective index from the filling factor was calculated for both grating types. The structures were manufactured by the Bosch-process. The required structural parameters for a continuous profile require an adaption of the fabrication process. Challenges are the depth and the slight positive slope of the structures. Starting point for the realization of the antireflective structures was the manufacturing of deep binary gratings. A rectangular structure and a hexagonal structure with period 50 mum and depth 500 mum were realized. Measurements with a THz time domain spectroscopy setup show an increase of the electric field amplitude of 15.2% for the rectangular grating and 21.76% for the hexagonal grating. The spectral analysis shows that the bandwidth of the hexagonal grating reaches from 0.1 to 2 THz.
Brückner
Claudia
C
Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Albert-Einstein-Strasse 7,07745 Jena, Germany. Claudia.Brueckner@iof.fraunhofer.de
Käsebier
Thomas
T
Pradarutti
Boris
B
Riehemann
Stefan
S
Notni
Gunther
G
Kley
Ernst-Bernhard
EB
Tünnermann
Andreas
A