High aspect ratio gratings are of interest for a couple of applications. Especially artificial birefringence based on zero order dielectric gratings are calling for small pitches (e.g. < 450 nm) and a high aspect ratio (e.g. > 10 in fused silica). One of the most difficult problems is to reach the optical parameters that are demanded. Based on e- beam writing, ion beam etching, reactive ion beam etching and chromium coating we developed a technique for the fabrication of such gratings. In result, we reached phase retardation between TM and TE polarization of more than 90 degree(s). An iterative step technique allows realization of the phase retardation of accuracy better than 1%. The highest aspect ratios of the gratings, we fabricated, were in the range of about 25 at 440 nm period and 100 nm gap.

Date Published: 31 August 1999
PDF: 8 pages
Proc. SPIE 3879, Micromachine Technology for Diffractive and Holographic Optics, (31 August 1999); doi: 10.1117/12.360534

Published in SPIE Proceedings Vol. 3879:
Micromachine Technology for Diffractive and Holographic Optics
Sing H. Lee; J. Allen Cox, Editor(s)