Ultra Wideband Dual-Output Thin Film Lithium Niobate Intensity Modulator

Abstract

This paper presents the design, optimization, fabrication, and characterization of a dual-output, wideband, thin-film lithium niobate Mach-Zehnder Modulator (TFLN-MZM). The device is designed with ridge etched waveguides for operation at a 1.55 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m wavelength. The dual-output is achieved using a 2×2 multi-mode interference (MMI) splitter with an extinction ratio (ER) of over 40 dB. The measured DC half-wave voltage (V <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_\pi$</tex-math></inline-formula> ) is 1.02 V. To achieve wideband operation, segmented electrodes are optimized to provide both wideband index matching and low loss. Accordingly, the measured 3 dB bandwidth is 95 GHz and the radio-frequency (RF) electrode loss is 0.24 dB/(cm˙GHz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{1/2}$</tex-math></inline-formula> ). The motivation for this device is in balanced microwave photonic links (MPLs) for Radio-Frequency-over-Fiber (RFoF) applications.