Femtosecond laser direct writing of flexibly configured waveguide geometries in optical crystals: fabrication and application

Schematic illustration of a typical experimental setup for FsLDW operation.

Schematic illustrations FsLDW of (a) single-line waveguides based on smooth Type-Ⅰ modification, (b) stress-induced double-line waveguides based on two parallel Type-Ⅱ laser tracks, and (c) depressed-cladding waveguides.

Schematic illustration of nonlinear waveguide channels based on FsLDW single-/multi-line geometries.

(a) Schematic illustration of Y-branch waveguide channels based on FsLDW double-line geometry39. (b) The microscopic photograph of the splitting region in a FsLDW Yb:YAG waveguide splitter39. (c) The cross-sectional microscopic photograph of a FsLDW Nd:YAG waveguide array43. (d) Reconstructed refractive index profile of the fabricated waveguide array43. Scale bars denote 30 µm. Figure reproduced with permission from: (a, b) ref.39 and (c, d) ref.43, Optical Society of America.

(a) Schematic illustration of curved waveguide channels based on FsLDW depressed-cladding geometries34. (b) Schematic illustration of three-element 3D photonic-lattice-like cladding photonic structures for beam splitting and ring-shaped beam transformation31. Figure reproduced with permission from: (a) ref.34, SPIE; (b) ref.31, Optical Society of America.

Schematic illustration of a MZI EO modulator with Y-branch waveguide channels based on FsLDW double-line geometries58.

(a) Lasing performance of FsLDW curved Yb:YAG double-line waveguides with different curvature radii R38. (b–e) Output modal profiles of FsLDW beam splitters and ring-shaped beam transformers49, 50. Figure reproduced with permission from: (a) ref.38, Optical Society of America; (b, e) ref.49, Springer Nature; (c, d) ref.50, IEEE.

Modal profiles of SHG (1064→532 nm) and 1×4 beam splitting from photonic-lattice-like KTP cladding waveguides69.