FABRICATION, MODELING, AND CHARACTERIZATION OF FORM-BIREFRINGENT NANOSTRUCTURES

A 490-nm-deep nanostructure with a period of 200 nm was fabricated in a GaAs substrate by use of electron-beam lithography and dry-etching t echniques. The form birefringence of this microstructure was studied n umerically with rigorous coupled-wave analysis and compared with exper imental measurements at a wavelength of 920 nm. The numerically predic ted phase retardation of 163.3 degrees was found to be in close agreem ent with the experimentally measured result of 162.5 degrees, thereby verifying the validity of our numerical modeling. The fabricated micro structures show extremely large artificial anisotropy compared with th at available in naturally birefringent materials and are useful for nu merous polarization optics applications. (C) 1995 Optical Society of A merica