Plastic deformation as nature of femtosecond laser writing in YAG crystal

Abstract

Longitudinal inhomogeneity of tracks inscribed in a YAG crystal and the statistics of nonlinear transmittance of the writing beam is studied under conditions of direct femtosecond laser writing in non-thermal mode. Nonlinear transmittance fluctuations inherent in the laser writing were discovered, and their correlation with track inhomogeneity is established. A model of femtosecond laser writing in crystals is built that includes three modes of plastic deformation in the laser impact zone. The modification threshold of the femtosecond direct laser writing is identified with reaching yield stress.

3D Laser Writing of Low‐Loss Cross‐Section‐Variable Type‐I Optical Waveguide Passive/Active Integrated Devices in Single Crystals

“…Following a single scan at this mutation threshold, a circular-shaped track with a substantial positive RI change becomes apparent (Figure 1). Plastic deformation was proposed as the mechanism for ultrafast laser-induced modification in YAG single crystals, [44] which typically involves the generation of lattice point defects, dislocations, stacking faults, and twins. [45,46] The high resolution transmission electron microscope (HRTEM) images captured in the WG region provide a compelling proof for this hypothesis, highlighting edge dislocation and stacking fault in the Fourierfiltered image of the HRTEM image (Figure 4a) and three differ-ent orientations of lattice fringes (Figure 4b).…”

Optical Thin Films Fabrication Techniques—Towards a Low-Cost Solution for the Integrated Photonic Platform: A Review of the Current Status

“…Photolithography and FIB micromachining, on the other hand, are slower. In addition, materials, including glasses [149,150], crystals [19,151], and polymers [152,153], WG…”

“…Photolithography and FIB micromachining, on the other hand, are slower. In addition, materials, including glasses [149,150], crystals [19,151], and polymers [152,153], WG structures can now be written on directly. Compared to the most popular techniques for the development of WG, fs-laser writing has the advantages of quick production, versatility in WG design, high three-dimensional accuracy, and easy integration of the resulting WG structures with optical fiber E-beam lithography and PECVD.…”