Femtosecond laser fabrication of volume-phase gratings in CdSxSe1-x-doped borosilicate glass at a low repetition rate

摘要

Volume-phase gratings (VPGs) were fabricated in CdSxSe1-x quantum-dot-doped borosilicate glass at a low repetition rate (800 nm, 140 fs, 1 kHz). The VPGs were designed based on rigorous coupled wave analysis simulations. Results indicate that the inscribed thickness (L) is the key parameter to maximize the diffraction efficiency at order 1. Microscope images of the cross sections and diffraction efficiency measurements were taken in order to characterize the modification of the material at different laser-inscription parameters. A maximum VPG diffraction efficiency of 67% (at order 1) was achieved. Also, a refractive index change of Delta n = 2.25.10(-3) is estimated from these VPG diffraction efficiency measurements. The measurements regarding polarization-insensitive diffraction efficiency showed that the birefringence produced in the substrate is negligible. (C) 2019 Optical Society of America