Poly-Si/SiO/sub 2/ laminated walk-off polarizer having a beam-splitting angle of more than 20

A spatial walk-off polarizer having a split angle of more than 20/spl deg/ in both the 1.3 and 1.5 /spl mu/m wavelength regions has been fabricated for the first time. The polarizer consists of alternate laminated layers of poly-Si and silica. The new polarizer makes the best use of the characteristics of crystal Si, namely high refractive index, and low absorption coefficients in the longer wavelength regions. A rather simplified fabrication process that utilizes the RF sputtering method is also proposed, in which only the oxygen-intake valve is used to control the deposition of poly-Si and silica layers from a single-crystal Si target. The fabricated polarizer has beam splitting angles as large as 22 and 21/spl deg/ at wavelengths of 1.30 and 1.55 /spl mu/m, respectively, being roughly four times larger than those of rutile or calcite.