No abstract

The waveguide beamsplitters with diverse configurations in LiNbO 3 crystal have been produced by direct femtosecond laser writing of a family of optical-lattice-like cladding structures. By on demand design of the lattice tracks with "defect" lines, the efficient beam guiding and tailoring have been implemented in the structures. With a family of three-element integration of structures, three-dimensional (3-D) 1 × 3 beamsplitting at the telecommunication wavelength of 1550 nm was realized. Different from the Type I modification of LiNbO 3 waveguides, the guiding cores of the optical-lattice-like cladding waveguide structures we fabricated locate in regions that are surrounded by the laser-induced-tracks. This paper opens the alternative way to construct complex integrated platforms in LiNbO 3 crystal by using femtosecond laser writing.

No abstract

No abstract

We report on the fabrication of the dual-line waveguides and cladding waveguide in z-cut MgO:LiNbO 3 crystal by femtosecond laser inscription. Due to the diverse modification of refractive index along TE/TM polarization induced by femtosecond laser pulses, the two geometries exhibit different guiding performances: the dual-line waveguides only support extraordinary index polarization, whilst the depressed cladding waveguide supports guidance along both extraordinary and ordinary index polarizations. The measured optical damage of these waveguides at the wavelength of 532 nm is higher than that of the previously reported ion-implanted waveguides in Zr-doped LiNbO 3 . The propagation loss of depressed cladding waveguide is measured as low as 0.94 dB/cm at 632.8 nm wavelength. It is found that the optical damage threshold (~10 5 W/cm 2 ) of the dual-line waveguide is one order of magnitude higher than that of the cladding waveguide (~10 4 W/cm 2 ).