Fabrication of Bragg gratings with deep grooves in LiNbO3 ridge optical waveguide

Abstract

The fabrication of LiNbO3 (LN) Bragg gratings, which have the grooves of 400nm depth, in LN ridge optical waveguide is shown in this paper. The 400nm depth grooves in LN Bragg gratings with high uniformity, precision and no damage were achieved for the first time. In order to fabricate the fine structure of LN Bragg gratings, we optimized the condition for LN dry etching and introduced the Cr metal as a mask material to our fabrication process. We also have investigated the favorable structure to realize the large optical group delay and discussed the importance to fabricate the Bragg gratings with deep grooves. We successfully fabricated Bragg gratings in LN ridge optical waveguide and demonstrated the measurement of transmission property. The etching process developed in this paper brought good performance to the fabrication of the deep grooves in LN Bragg gratings.From these results, the possibility of large group delay and slow-wave electro-optic modulators in LN optical waveguides was revealed.