Optical coupling between pairs of waveguides made in lithium niobate crystal by means of femtosecond laser writing

E.. NEYRA ; G.A. TORCHIA; S. SUAREZ

Bruselas

Conferencia; SPIE Photonics Europe; 2014

SPIE

During the last decade, femtosecond laser writing in optical materials has shown a remarkable increase in the number of scientific and technological works published in internationals journals. Some advantages of this technique can be pointed as: one step process, possibility of 3D recorded, low cost and easy to implement on a wide range of materials. This technique also offers different optical circuit fabrication with applications in various technological fields ranging from photonics to medicine among others. In this work we study the optical coupling between pairs of waveguides fabricated by femtosecond laser writing technique. In particular, these structures are constructed by written single tracks above the optical breakdown threshold so called type II structures. The study of this coupling has been carried out both experimentally as well as by simulations based on a technique known as "beam propagation method ?(BPM). For the last, we have used commercial software (RSoft) and its particular tool, BeamProp. The waveguides were fabricated by using a micro-machining system based on a Chirped Pulse Amplification (CPA) femtosecond laser by Spectra Physics (USA). In this work, we explore the variation of the light intensity at the output from each pair of waveguides, as a function of separation between them and considering a resultant refractive index profile for these guiding structures. Good agreement for simulations and experiments has been obtained in this work. The results presented in this paper can be a suitable tool for optimize the design of optical circuits for technological purpose.