Fabrication and Measurement of Sidewall Gratings Integrated in Hybrid As2S3 -Ti:LiNbO3 Optical Waveguides

• Published in: Journal of lightwave technology Vol. 32; no. 17; pp. 2989 - 2995
• Main Authors: Xin Wang, Yifeng Zhou, Madsen, Christi K.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2014; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Couplings; Gratings; Lithium niobate; Optical device fabrication; Optical waveguides; Reflectivity; Strips; sidewall gratings; integrated optical devices; Arsenic tri-sulfide; linear tapers; waveguides; lithium niobate; electron beam lithography
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2014.2334054

In this paper, we demonstrated the fabrication and measurement of sidewall gratings integrated in a hybrid type of optical waveguide: As 2 S 3 -Ti:LiNbO 3 . This hybrid waveguide is constructed by patterning arsenic tri-sulfide (As 2 S 3 ) strips on the midline of titanium-diffused channel waveguide in lithium niobate (Ti:LiNbO 3 ). Sidewall gratings are written on both sidewalls of As 2 S 3 strips by electron beam lithography (EBL) with 3% PMMA resist and a dose 350 μC/cm 2 at 50-kV electrons. The measured reflectance bandwidth was between 2.4 and 6.7 nm. Coupling coefficients ranging from 2.5 to 8.9 mm -1 were obtained. A transmission peak with a 3-dB bandwidth of ~0.25 nm was observed in the rejection band of a 432 μm-long phase-shifted sidewall grating. Such sidewall gratings integrated in hybrid As 2 S 3 -Ti:LiNbO 3 waveguide can be used for numerous integrated optical devices including optical filters, switches, modulators, lasers, sensors, and wavelength division multiplexing (WDM).