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Sub-micrometer epsilon-near-zero electroabsorption modulators enabled by high-mobility cadmium oxide

IEEE Photonics Journal (Online)

Campione, Salvatore; Wood, Michael G.; Serkland, Darwin K.; Parameswaran, Sivasubramanian P.; Ihlefeld, Jon I.; Luk, Ting S.; Wendt, J.R.; Geib, Kent; Keeler, Gordon A.

Here, epsilon-near-zero materials provide a new path for tailoring light-matter interactions at the nanoscale. In this paper, we analyze a compact electroabsorption modulator based on epsilon-near-zero confinement in transparent conducting oxide films. The non-resonant modulator operates through field-effect carrier density tuning. We compare the performance of modulators composed of two different conducting oxides, namely indium oxide (In2O3) and cadmium oxide (CdO), and show that better modulation performance is achieved when using high-mobility (i.e. low-loss) epsilon-near-zero materials such as CdO. In particular, we show that non-resonant electroabsorption modulators with sub-micron lengths and greater than 5 dB extinction ratios may be achieved through the proper selection of high-mobility transparent conducting oxides, opening a path for device miniaturization and increased modulation depth.

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High-mobility transparent conducting oxides for compact epsilon-near-zero silicon integrated optical modulators

Optics InfoBase Conference Papers

Wood, Michael G.; Campione, Salvatore; Serkland, Darwin K.; Parameswaran, Sivasubramanian P.; Ihlefeld, Jon I.; Luk, Ting S.; Wendt, J.R.; Geib, Kent M.; Keeler, Gordon A.

We study the role of carrier mobility in transparent conducting oxides integrated into epsilon-near-zero modulators. High-mobility materials including CdO enable sub-micron length electroabsorption modulators through >4dB/μm extinction ratios.

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Enhanced infrared detectors using resonant structures combined with thin type-II superlattice absorbers

Applied Physics Letters

Goldflam, Michael G.; Kadlec, Emil A.; Olson, B.V.; Klem, John F.; Hawkins, Samuel D.; Parameswaran, Sivasubramanian P.; Coon, Wesley T.; Keeler, Gordon A.; Fortune, Torben R.; Tauke-Pedretti, Anna; Wendt, J.R.; Shaner, Eric A.; Davids, Paul D.; Kim, Jin K.; Peters, D.W.

We examined the spectral responsivity of a 1.77 μm thick type-II superlattice based long-wave infrared detector in combination with metallic nanoantennas. Coupling between the Fabry-Pérot cavity formed by the semiconductor layer and the resonant nanoantennas on its surface enables spectral selectivity, while also increasing peak quantum efficiency to over 50%. Electromagnetic simulations reveal that this high responsivity is a direct result of field-enhancement in the absorber layer, enabling significant absorption in spite of the absorber's subwavelength thickness. Notably, thinning of the absorbing material could ultimately yield lower photodetector noise through a reduction in dark current while improving photocarrier collection efficiency. The temperature- and incident-angle-independent spectral response observed in these devices allows for operation over a wide range of temperatures and optical systems. This detector paradigm demonstrates potential benefits to device performance with applications throughout the infrared.

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12 Results
12 Results