Bragg Gratings Made in Reverse Proton Exchange Lithium Niobate Waveguides With a Femtosecond IR Laser and a Phase Mask

摘要

Three-decibel reflecting Bragg gratings were made in buried reverse proton exchange lithium niobate waveguides with high-power femtosecond infrared radiation from a regenerative Ti:sapphire amplifier and a phase mask. Two superposed gratings were observed: a relief grating on the surface of the crystal with a 300-nm corrugation depth and a subsurface grating in phase with the surface grating. Atomic force and optical microscopy were used to characterize the grating's physical structure.