Laser-Inscribed Stress-Induced Birefringence of Sapphire.
Hua FanMeguya RyuReo HondaJunko MorikawaZhen-Ze LiLei WangJovan MaksimovicSaulius JuodkazisQi-Dai ChenHong-Bo SunPublished in: Nanomaterials (Basel, Switzerland) (2019)
Birefringence of 3 × 10 - 3 is demonstrated inside cross-sectional regions of 100 μ m, inscribed by axially stretched Bessel-beam-like fs-laser pulses along the c-axis inside sapphire. A high birefringence and retardance of λ / 4 at mid-visible spectral range (green) can be achieved using stretched beams with axial extension of 30-40 μ m. Chosen conditions of laser-writing ensure that there are no formations of self-organized nano-gratings. This method can be adopted for creation of polarization optical elements and fabrication of spatially varying birefringent patterns for optical vortex generation.