Gigahertz speed operation of epsilon-near-zero silicon photonic modulators

Journal Article · 21 February 2018 · Optica

DOI: https://doi.org/10.1364/optica.5.000233 · OSTI ID:1421586

Wood, Michael G.  ^[1]; Campione, Salvatore  ^[1]; Parameswaran, S. ^[1]; Luk, Ting S. ^[1]; Wendt, Joel R. ^[1]; Serkland, Darwin K. ^[1]; Keeler, Gordon A. ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Optical communication systems increasingly require electro-optical modulators that deliver high modulation speeds across a large optical bandwidth with a small device footprint and a CMOS-compatible fabrication process. Although silicon photonic modulators based on transparent conducting oxides (TCOs) have shown promise for delivering on these requirements, modulation speeds to date have been limited. Here, we describe the design, fabrication, and performance of a fast, compact electroabsorption modulator based on TCOs. The modulator works by using bias voltage to increase the carrier density in the conducting oxide, which changes the permittivity and hence optical attenuation by almost 10 dB. Under bias, light is tightly confined to the conducting oxide layer through nonresonant epsilon-near-zero (ENZ) effects, which enable modulation over a broad range of wavelengths in the telecommunications band. Our approach features simple integration with passive silicon waveguides, the use of stable inorganic materials, and the ability to modulate both transverse electric and magnetic polarizations with the same device design. Using a 4-μm-long modulator and a drive voltage of $2{\mathrm{V}}_{pp}$, we demonstrate digital modulation at rates of 2.5 Gb/s. We report broadband operation with a 6.5 dB extinction ratio across the 1530–1590 nm band and a 10 dB insertion loss. This work verifies that high-speed ENZ devices can be created using conducting oxide materials and paves the way for additional technology development that could have a broad impact on future optical communications systems.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); SNL Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: NA0003525
• OSTI ID: 1421586
• Alternate ID(s): OSTI ID: 1432341
• Report Number(s): SAND2018-0422J; 659953
• Journal Information: Optica, Vol. 5, Issue 3; ISSN 2334-2536
• Publisher: Optical Society of AmericaCopyright Statement
• Country of Publication: United States
• Language: English