Femtosecond-Laser Writing of Tracks with Depressed Refractive Index in Crystals

摘要

Fabrication and characterization of tracks in calcium fluoride and crystalline quartz are described. These tracks were created using ultrashort near-infrared (NIR) laser pulses in a manner similar to that of writing waveguides in glasses. Unlike the tracks in glasses the laser-written tracks in crystals have the depression of the refractive index. The magnitude of the depression is about 0.01 or more that may enable creation of high-contrast structures in crystals. Depending on the writing conditions the tracks' diameter may vary from around 1μm to 10 μm.