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

Abstract

Optical waveguides are far more than mere connecting elements in integrated optical systems and circuits. Benefiting from their high optical confinement and miniaturized footprints, waveguide structures established based on crystalline materials, particularly, are opening exciting possibilities and opportunities in photonic chips by facilitating their on-chip integration with different functionalities and highly compact photonic circuits. Femtosecond-laser-direct writing (FsLDW), as a true three-dimensional (3D) micromachining and microfabrication technology, allows rapid prototyping of on-demand waveguide geometries inside transparent materials via localized material modification. The success of FsLDW lies not only in its unsurpassed aptitude for realizing 3D devices but also in its remarkable material-independence that enables cross-platform solutions. This review emphasizes FsLDW fabrication of waveguide structures with 3D layouts in dielectric crystals. Their functionalities as passive and active photonic devices are also demonstrated and discussed.

Lab‐on‐a‐Contact Lens Platforms Fabricated by Multi‐Axis Femtosecond Laser Ablation

“…[19] Femtosecond lasers are currently used for the fine machining of stents, [20] catheters, heart valves, polymer fibers and tubes. [21,22] Recent studies also report on the use of femtosecond laser ablation to produce hierarchical, periodic structures [23][24][25][26][27] in optical crystals, [28] and to aid the synthesis of nanoparticles for medical applications. [22,29,30] Here, femtosecond laser inscription technology was applied to commercial contact lens devices.…”

Anisotropic Superhydrophobic Properties of Bioinspired Surfaces by Laser Ablation of Metal Substrate inside Water

“…Laser fabrication has been developed to construct superhydrophobic surfaces. [ 19,24–29 ] Although the femtosecond laser is a potential fabrication method owing to its low thermal effect, its poor economy, and low efficiency hinder its applications, [ 30,31 ] while the nanosecond laser has found wide applications in microfabrication processing with much better characteristics of high stability, and high energy. However, the heat accumulation by nanosecond laser scribing and dicing causes significant thermal damage to the substrate.…”

Diode-Pumped Fluorescence in Visible Range From Femtosecond Laser Inscribed Pr:LuAG Waveguides

“…A large number of techniques have been employed with the aim of fabricating waveguide structures with high optical performances [21][22][23]. Femtosecond laser inscription (FLI) has emerged as an unprecedented three dimensional (3D) waveguide fabrication technology, which can be manifested in plentiful transparent materials [21,[24][25][26][27]. During the FLI process, high optical energy at the laser focus would be deposited inside the materials due to the nonlinear multi-photon absorption, resulting in a highly localized structural modification to the materials, one example of which is refractive index (RI) change that is responsible for the formation of waveguide structures [28,29].…”