Birefringence of 3×10−33×10-3 is demonstrated inside cross-sectional regions of 100 μμ m, inscribed by axially stretched Bessel-beam-like fs-laser pulses along the c-axis inside sapphire. A high birefringence and retardance of λ/4λ/4 at mid-visible spectral range (green) can be achieved using stretched beams with axial extension of 30–40 μμ 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.
【Research Paper】”Laser-Inscribed Stress-Induced Birefringence of Sapphire”
(School of Materials and Chemical Technology/Dr. Junko Morikawa and Dr. Saulius Juodkazis)
“Laser-Inscribed Stress-Induced Birefringence of Sapphire”
Nanomaterials 2019, 9(10), 1414.（DOI: https://doi.org/10.3390/nano9101414）