TECHNOLOGY OF THREE-DIMENSIONAL FEMTOSECOND WRITING FOR CREATING INTEGRATED OPTICS ELEMENTS

• Main Authors: N. N. Skryabin, M. A. Bukharin, S. M. Kostritskii, Yu. N. Korkishko, V. A. Fedorov, D. V. Khudyakov
• Format: Article
• Language: English
• Published: CRI «Electronics» 2018-03-01
• Series: Радиопромышленность
• Subjects: femtosecond writing; lithium niobate; refractive index; electro-optical modulator; waveguide; integrated optics
• Online Access: https://www.radioprom.org/jour/article/view/285
• ISSN: 2413-9599; 2541-870X

A permanent change in the refractive index affected by femtosecond laser pulses at a small depth (2–15 μm) under the surface of a lithium niobate crystal has been studied. Based on the technology of femtosecond writing, solutions for the problems of industrial electro-optical modulators are proposed. For interference schemes obtained by lithographic methods, a correction track with a reduced refractive index (Δn = –3 ∙ 10–3) was writing to reduce the coupling between the channels of the splitter and to increase its temperature stability. Apart from the above, a possibility of a fully femtosecond writing of a depressed cladding waveguide with a core diameter of 12 μm at small depths below the surface of a lithium niobate crystal has been demonstrated to create a noninterference electro-optical modulator based on the effect of electrooptic rotation of polarization.