title: Fabrication of polarization-independent waveguides deeply buried in lithium niobate crystal using aberration-corrected femtosecond laser direct writing.
abstract: Writing optical waveguides with femtosecond laser pulses provides the capability of forming three-dimensional photonic circuits for manipulating light fields in both linear and nonlinear manners. To fully explore this potential, large depths of the buried waveguides in transparent substrates are often desirable to facilitate achieving vertical integration of waveguides in a multi-layer configuration, which, however, is hampered by rapidly degraded axial resolution caused by optical aberration. Here, we show that with the correction of the spherical aberration, polarization-independent waveguides can be inscribed in a nonlinear optical crystal lithium niobate (LN) at depths up to 1400 μm, which is more than one order of magnitude deeper than the waveguides written with aberration uncorrected femtosecond laser pulses. Our technique is beneficial for applications ranging from miniaturized nonlinear light sources to quantum information processing.
authors.affiliation: State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.|School of Physical Science and Technology, Shanghai Tech University, Shanghai 200031, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.|School of Physical Science and Technology, Shanghai Tech University, Shanghai 200031, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Qi
authors.affiliation: State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.|School of Physical Science and Technology, Shanghai Tech University, Shanghai 200031, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Liu
authors.affiliation: State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liao
authors.affiliation: State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chu
authors.affiliation: State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.|State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.|Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Cheng