Key kinematic parameters in low-loss power splitter written by femtosecond laser micromachining

Abstract

In this work we design, fabricate and characterize a 1x2 Y-branch powersplitter based on simplied coherent coupling. This device was constructed by type II waveguide structures inscribed by direct femtosecond laser writing technique in x-cut lithium niobate crystal. First of all, a theoretical study that links the kinematic and writing fuence of the process is developed so this allows us to establish the design trade o and justify the best geometry chosen. Then, the design was optimized and tested by using a commercial software, it results a compact and low-loss photonic circuit. The eciency of the proposed device is compared with two others: curved and straight splitter. Finally, the experimental results were compared with simulations and then a statistical analysis of multiple comparisons was also conducted, obtaining 3.7dB0.1dB insertion losses and 4.5% of the unbalanced coupling ratio.