Lithium Niobate Electro-Optic Racetrack Modulator Etched in Y-Cut LNOI Platform

An electro-optic modulator (EOM) based on a racetrack resonator coupled to a waveguide using butterfly multi-mode interference (MMI) coupler is fabricated on Y-cut lithium niobate (LN) thin film. This is the first demonstration of a LN EOM in which the thin film of LN is etched in a Y-cut substrate...

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Bibliographic Details
Main Authors: Mohamed Mahmoud, Lutong Cai, Christian Bottenfield, Gianluca Piazza
Format: Article
Language:English
Published: IEEE 2018-01-01
Series:IEEE Photonics Journal
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Online Access:https://ieeexplore.ieee.org/document/8275483/
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Summary:An electro-optic modulator (EOM) based on a racetrack resonator coupled to a waveguide using butterfly multi-mode interference (MMI) coupler is fabricated on Y-cut lithium niobate (LN) thin film. This is the first demonstration of a LN EOM in which the thin film of LN is etched in a Y-cut substrate using chlorine-based inductively coupled plasma reactive ion etching, a process, which is readily compatible with semiconductor fabrication facility. The Y-cut LNOI platform is interesting for the integration of electro-optic and acousto-optic components, since differently from any other LN cut it facilitates taking advantage of the maximum electro-optic and piezoelectric coefficients of LN. Coupling to the racetrack was enabled using a butterfly MMI coupler, which offered operation near the critical coupling condition, hence increasing the extinction ratio (ER) of the modulator. An unloaded quality factor of 1.3 &#x00D7; 10<sup>5</sup> was extracted for this device, which is equivalent to a propagation loss of 2.3 dB&#x002F;cm. Modulation bandwidth of 4 GHz, wavelength tuning rate of 0.32 pm&#x002F;V, and an ER of more than 10 dB were experimentally measured for the EOM.
ISSN:1943-0655