Optimisation of microstructured waveguides in z-cut LiNbO3 crystals
  We present a practical approach to the numerical optimisation of the guiding properties of buried microstructured waveguides, which can be fabricated in a z-cut lithium niobate (LiNbO3) crystal by the method of direct femtosecond laser inscription. We demonstrate the possibility to extend the spectral range of low-loss operation of the waveguide into the mid-infrared region beyond 3{\mu}m. 
Huseyin Karakuzu, Mykhaylo Dubov, Sonia Boscolo, Leonid A.Melnikov,   Yulia A. Mazhirina
physics.optics