Phenomenological studies of femtosecond laser ablation on optical thin films for integrated photonics

Abstract

In this work, we present a well-supported procedure to fabricate ridge optical waveguides onto thin films of PLZT by femtosecond laser ablation. To achieve smooth-guiding structures that guarantee good optical performance we have studied the characteristics of ablation threshold for different kinematic conditions of fs laser machining and we have also explored the different ablation regimens for several fluences reached. Furthermore, we characterized the morphology and roughness of ridge waveguides through a modal analysis of scattering loss for waveguides conducted by single and multiple scans. An innovative phenomenological model that describes the sidewall roughness to process parameters is proposed in this paper. With this approach, it is possible to extend the manufacturing method of smooth-guiding structures to many optical thin films by fs micromachining, so as to create integrated photonics devices that can be addressed to different technological applications.