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Item type:Publication, Access status: without files , SiC-SiO2 MEMS-DBR based widely tunable optical filters around 1550 nm with narrow FWHMEver growing optical data transmission networks and miniaturization of spectroscopic equipment demand for small, energy efficient and mass-produced optical components. Here we present distributed Bragg reflector (DBR) mirror based widely tunable optical Fabry-Perot filters comprising a novel material combination namely, silicon carbide (SiC) and silicon dioxide (SiO ) layers with refractive indices of 2.46 and 1.45, respectively. The resulting refractive index step of 1, provides high reflectivites (>99.5 %) with wide stopbands of more than 300 nm [1]. Hence, large wavelength tuning range and a narrow full width at half maximum (FWHM) filtered signals can be produced. Structuring the dielectric layers by surface micromachining creates a free standing movable mirror supported by four beams. Due to inherent stress created during low-temperature plasma enhanced chemical vapor depositions (PECVD) we obtain a tunable stable plane concave resonator. In the end the cross section of a filter shows a fixed bottom DBR deposited on a silicon substrate, a tunable airgap and an electrothermally actuated top MEMS DBR with a gold electrode for heating current I . On the substrate backside where the filtered signal is exiting an anti-reflection coating is deposited.Publicationtype: Conference Paper42 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , All-dielectric metasurfaces for infrared absorption spectroscopy applicationsWe present a nanophotonic method capable of detecting mid-infrared molecular fingerprints without the need for spectrometry, frequency scanning, or moving mechanical parts. We leverage dielectric metasurfaces featuring ultra-sharp resonances each tuned to discrete frequencies, enabling us to sample molecular absorption signatures over the mid-IR spectral range.Publicationtype: Conference Paper7 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Permanent optimization of large-FSR dual-microring bandpass filters(2019-06); ; Energy-efficient communication links are crucial for future processors and optoelectronic microchips in order to continue growths in computing and information technologies [1]. Wavelength-division multiplexing (WDM) techniques based on silicon photonic circuits are ideal for high bandwidths data communication systems with small footprints [2,3]. Compact double ring resonators (DRRs) provide excellent properties to realize spectral filters with flat-top transmission characteristics, providing a steep roll-off with low channel crosstalk at dense frequency grids. Hence, cascaded DRRs as illustrated in Fig. 1 (a) are well-suited for integrated WDM systems on optoelectronic microchips. The high refractive index of silicon facilitates small ring perimeters and the wide free spectral range (FSR ∝1/Lr) enables multiplexing tens of data channels to a common bus waveguide. The high energy-efficiency which is enhanced by the strong thermo-optic effect (TOE) combined with the short physical lengths is another relevant advantage of the compact size. However, manufacturing variability and associated photonic component deviations remain a serious drawback [4]. Hence, most recent works use thermal heaters for the dynamic filter control as well as to counterbalance inevitable manufacturing deviations [5-7].Publicationtype: Conference Paper176 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Enhanced circular dichroism and chiral sensing with bound states in the continuumWe reveal that optical chirality at the nanoscale can be boosted dramatically by bound states in the continuum (BIC). We predict the enhancement of chiroptical signals from nanostructures supporting quasi-BICs in mid-IR with a record-high efficiency.Publicationtype: Conference Paper8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , High Temperature Optical MetamaterialsWe investigate spectrally selective high temperature stable metamaterial emitters for thermophotovoltaics. We demonstrate band-edge emitters based on a W-Hf02 multilayer metamaterial stable up to 1400°C. Conditions for improved selectivity and thermal stability are discussed.Publicationtype: Conference Paper18 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , All-Dielectric Metasurfaces for Infrared Absorption Spectroscopy Applications(2019-05-01); 6