Design conditions in the middle range for implementation of integrated ring resonators in LiNbO3 by direct laser writing

P. PAGANO; D. PRESTI; R. PEYTON; F. VIDELA; G. A. TORCHIA

IET CONTROL THEORY AND APPLICATIONS

INST ENGINEERING TECHNOLOGY-IET

Año: 2020

1751-8644

The aim of this work is to design an integrated optical ring resonator to be implemented in LiN bO 3 with a 2.5 mm radius and anoperating wavelength of 1550 nm. Considering these ring parameters, a free spectral range (FSR) of 71.54 pm and a quality factorof approximately 5×10 5 were calculated. I will apply results of this work to improve the implementation of a technology basedon direct laser writing on Lithium Niobate crystals. As it is well known FDTD (Finite Difference Time Domain) method requiresmemory and is time-consuming for processing circuits with large footprints (a few square mm). As a result, for our simulations,we used the RSoft suite, in particular, the beam propagation method (BPM) which allows us to simulate large bends. Softwaredesign tools commonly represent circles by closed polygons whose geometrical parameters are not optimized to obtain bendinglosses as least as possible, as suggested by coherent coupling theory. In this sense, the suitable determination of a splice angle,shape and length for segments are key parameters in our ring design. For this purpose, an ad hoc software was implemented toovercome this drawback. In summary, a 250 sided polygon side showed a suitable coupling performance and established a newlayout approach for middle range rings.