  In this work, for the first time of our knowledge, we present a
well-supported procedure to fabricate ridge optical waveguides onto thin films
of PLZT by femtosecond laser ablation. In order to achieve smooth guiding
structures to guarantee good optical performance, we have studied the ablation
threshold characteristics for different kinematic conditions of fs laser
machining and also we have explored the different ablation regimens for several
fluencies reached. Besides, we characterize the morphology and roughness of
ridge waveguides through a modal and scattering loss analysis, for waveguides
made with single and multiple scan. An innovative phenomenological model that
relates the sidewall roughness to process parameters is proposed in this paper.
Conducting this approach it is possible to extend the fabrication method of
smooth guiding structures by fs micromachining to many optical thin films in
order to develop integrated photonics devices addressed to different
technological applications.
