Femtosecond laser direct-write waveplates based on stress-induced birefringence

摘要

The use of femtosecond lasers to introduce controlled stress states hasrecently been demonstrated in silica glass. We use this technique, incombination with chemical etching, to generate and control stress-inducedbirefringence over a well-defined region of interest, demonstratingdirect-write wave plates with precisely tailored retardance levels. Thistailoring enables the fabrication of laser-written polarization optics that canbe tuned to any wavelength for which silica is transparent and with a clearaperture free of any laser modifications. Using this approach, we achievesufficient retardance to act as a quarter-wave plate. The stress distributionwithin the clear aperture is analyzed and modeled, providing a generic templatethat can be used as a set of design rules for laser-machined polarizationdevices.