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.
Sci Rep. 2017 Jan 23;7:41211. doi: 10.1038/srep41211.
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.
利用飞秒激光脉冲写入光学波导，为以线性和非线性方式操控光场提供了形成三维光子电路的能力。为了充分挖掘这一潜力，人们通常希望在透明衬底中形成具有较大掩埋深度的波导，以利于在多层结构中实现波导的垂直集成，但这受到由像差导致的轴向分辨率迅速劣化的阻碍。在这里，我们展示了通过对像差的校正，可以在非线性光学晶体铌酸锂（LN）中写入深度达 1400μm 的偏振无关波导，这比用未校正像差的飞秒激光脉冲写入的波导深一个数量级以上。我们的技术有利于从小型化非线性光源到量子信息处理等各种应用。
