Lithium niobate optical modulators: Devices and applications

Abstract

Optical modulators, using acousto-optic, magneto-optic or electro-optic effects, as the principal components for external modulation of lightwaves, have presently played the important role in modern long-haul ultra-high speed optical communications and photonic signal processing systems. LiNbO 3 is an ideal host material for such modulators. In this paper we present: (i) a brief overview the electro-optic interaction in LiNbO 3 optical waveguides and the travelling electric waves for modulation; (ii) fabrication techniques of optical waveguides and electrodes for the excitation of microwave and millimeter waves, including the prospects of the uses of ultra-thick “brick-wall like” type by synchrotron deep X-ray LIGA process; (iii) a comprehensive modelling of the travelling wave electrodes for the design of interferometric optical modulators, including different electrode structures. Tilted and thick and “brick-wall” like electro-plated electrodes are modelled and confirmed with implemented modulators operating up to 26 GHz in diffused LiNbO 3 optical interferometric waveguide structures; (iv) the design and implementation of LiNbO 3 single or dual drive as modulators for modulating lightwaves in modern transmission systems as ultra-high speed pulse carvers, generators of modulation formats (NRZ, RZ, CS-RZ, DPSK, DQPSK, etc.) and photonic signal processors.