Anisotropic reflection from femtosecond laser directly-written structures

Summary form only given. In recent years, the use of focused femtosecond laser pulses to direct-write three-dimensional arrays of waveguides, couplers and other devices within the bulk of glass has become increasingly prevalent. The study of the physical damage created by such lasers has also begun to be investigated with properties such as anomalous anisotropic light scattering, and uniaxial birefringence being observed in irradiated samples. At present, the microscopic processes underlying such anisotropies remain unclear. We have identified an additional property present in fused silica which is apparent after being irradiated by an amplified Ti:sapphire femtosecond laser system-strong reflection from the damaged region occurs only along the direction of polarization of the writing laser.