Abstract
The femtosecond laser micromachining of transparent optical materials offers a powerful and feasible solution to fabricate versatile photonic components towards diverse applications. In this work, we report on a new design and fabrication of ridge waveguides in LiNbO3 crystal operating at the mid-infrared (MIR) band by all-femtosecond-laser microfabrication. The ridges consist of laser-ablated sidewalls and laser-written bottom low-index cladding tracks, which are constructed for horizontal and longitudinal light confinement, respectively. The ridge waveguides are found to support good guidance at wavelength of 4 μm. By applying this configuration, Y-branch waveguiding structures (1 × 2 beam splitters) have been produced, which reach splitting ratios of ∼1:1 at 4 μm. This work paves a simple and feasible way to construct novel ridge waveguide devices in dielectrics through all-femtosecond-laser micro-processing.
Highlights
As the basic components in integrated photonics, optical waveguides could confine light propagation within small volumes with dimensions of micrometric or sub-micrometric scales, in which higher optical intra-cavity intensities could be achieved compared with bulk materials[1]
The novel ridge waveguide and Y-branch structures have been achieved in LiNbO3 crystal via all-laser-micromachining, which pave a promising way for a wide variety of applications in many disciplines
The novel ridge waveguides in LiNbO3 crystal are fabricated by all-laser-micromachining technique
Summary
As the basic components in integrated photonics, optical waveguides could confine light propagation within small volumes with dimensions of micrometric or sub-micrometric scales, in which higher optical intra-cavity intensities could be achieved compared with bulk materials[1]. In dielectric crystals, a planar waveguide may be formed by ion irradiation or ion implantation in the first step, and second processing with other techniques, such as wet or dry etching, ion-beam enhanced etching, diamond blade dicing, and laser ablation, on the planar waveguide may be implemented to remove the selected parts of the planar waveguide surface, constructing the ridge waveguides[12,13,14,15,16] These traditional fabrication solutions require combination of at least two-step processing of diverse techniques. Our work demonstrated a flexible and convenient manner to construct novel ridge geometries in dielectrics via all-femtosecond-laser micro-processing for photonic applications
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