Fabrication of semi-cylindrical channels for one-dimensional fiber array edge couplers

Abstract: Photonic Integrated Circuits (PICs) are essential for high-speed and compact optoelectronic applications, yet efficient optical coupling to PIC remains a critical challenge, where minimizing insertion losses is crucial for high-performance applications. Fiber arrays are commonly used as edge couplers for PICs. In this work, we demonstrate the fabrication of semi-cylindrical channels on glass substrates using femtosecond laser micromachining for fiber arrays edge couplers. This method enables the formation of narrow, well-defined grooves in glass substrates with submicron accuracy, facilitating reliable fiber positioning for improved coupling efficiency. Experimental results demonstrate the feasibility of this approach for dense fiber arrays, with a narrow separation of \sim 3 {\mu}m.