Universität Stuttgart

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Institute: search.filters.UBSInstitut.Institut für Elektrische und Optische NachrichtentechnikAuthor: search.filters.author.Hoppe, Niklas

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    ItemOpen Access
    Silicon integrated dual-mode interferometer with differential outputs
    (2017) Hoppe, Niklas; Scheck, Pascal; Sweidan, Rami; Diersing, Philipp; Rathgeber, Lotte; Vogel, Wolfgang; Riegger, Benjamin R.; Southan, Alexander; Berroth, Manfred
    The dual-mode interferometer (DMI) is an attractive alternative to Mach-Zehnder interferometers for sensor purposes, achieving sensitivities to refractive index changes close to state-of-the-art. Modern designs on silicon-on-insulator (SOI) platforms offer thermally stable and compact devices with insertion losses of less than 1 dB and high extinction ratios. Compact arrays of multiple DMIs in parallel are easy to fabricate due to the simple structure of the DMI. In this work, the principle of operation of an integrated DMI with differential outputs is presented which allows the unambiguous phase shift detection with a single wavelength measurement, rather than using a wavelength sweep and evaluating the optical output power spectrum. Fluctuating optical input power or varying attenuation due to different analyte concentrations can be compensated by observing the sum of the optical powers at the differential outputs. DMIs with two differential single-mode outputs are fabricated in a 250 nm SOI platform, and corresponding measurements are shown to explain the principle of operation in detail. A comparison of DMIs with the conventional Mach-Zehnder interferometer using the same technology concludes this work.
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    ItemOpen Access
    Integrated dispersive structures for bandwidth-enhancement of silicon grating couplers
    (2020) Klenk, Rouven H.; Schweikert, Christian; Hoppe, Niklas; Nagy, Lotte; Elster, Raik; Vogel, Wolfgang; Berroth, Manfred
    In photonic integrated circuits grating couplers are commonly used to establish an efficient and stable fiber-to-chip link. However, the actual coupling efficiency of a fiber-to-chip interface depends strongly on the used wavelength and exhibits a maximum at a distinct target wavelength, determined by grating design parameters. In this paper, an enhancement of the optical bandwidth of silicon grating couplers by adding integrated dispersive structures is discussed. These are realized by single layers, prism-like geometries and additional silicon nitride gratings. Theoretical considerations for a bandwidth-enhancement by dispersive layers are performed and applied to an existing grating coupler design. A simulated 1dB-bandwidth of up to 90 nm at a maximum efficiency of - 0.65 dB in the C-band could be achieved, which is an enhancement to a factor of about 2 compared with the original coupler design.