Hybrid Femtosecond Laser Fabrication of Surface Y-Branch Waveguides in LiTaO<sub>3</sub> via Etching and Refractive Index Engineering

In this study, we present the development of a Y-branch superficial waveguide splitter that was fabricated using a combination of femtosecond laser writing and ablating techniques in a z-cut lithium tantalate (LiTaO3) wafer. By strategically switching focus objectives and adjusting the pulse energy, we successfully created ridge waveguides with femtosecond laser-ablated side-walls and written bottom boundaries. This unique ridge guiding structure exhibits remarkable polarization sensitivity and superior waveguiding performance, particularly at the telecommunication wavelength of 1.55 μm. The fabrication process leverages the precision and flexibility of femtosecond laser technology to achieve high-quality waveguides with well-defined geometries. The polarization sensitivity of the waveguide splitter is a significant advantage for applications in optical communication systems, where polarization control is crucial. The excellent waveguiding performance at 1.55 μm wavelength ensures efficient transmission and minimal loss, making this Y-branch splitter a promising candidate for integration into advanced photonic devices and systems.