We report on the single-step fabrication of stressed optical waveguides with tubular depressed-refractive-index cladding in phosphate glasses by the use of focused femtosecond hollow laser beams. Tubelike low index regions appear under direct exposure due to material rarefaction following expansion. Strained compacted zones emerged in domains neighboring the tubular track of lower refractive index, and waveguiding occurs mainly within the tube core fabricated by the engineered femtosecond laser beam. The refractive index profile of the optical waveguide was reconstructed from the measured transmitted near-field intensity.
© 2012 Optical Society of America
Original Manuscript: May 8, 2012
Revised Manuscript: June 20, 2012
Manuscript Accepted: June 27, 2012
Published: July 23, 2012
Xuewen Long, Jing Bai, Wei Zhao, Razvan Stoian, Rongqing Hui, and Guanghua Cheng, "Stressed waveguides with tubular depressed-cladding inscribed in phosphate glasses by femtosecond hollow laser beams," Opt. Lett. 37, 3138-3140 (2012)