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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 , Dispersion engineered photonic biosensor: from a chip-for-the-lab to a lab-on-chipPublicationtype: Doctoral Thesis175 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Manufacturing variability estimations for deposited silicon photonic circuitsWe present a comprehensive study of deposited silicon microring resonators for photonic-integrated circuitry. Refractive index, thickness, and widths variations are estimated. The statistical deviations are sufficiently low to realize photonic circuits of high quality for instance deposited on various substrates and integrated with heterogeneous materials.Publicationtype: Conference Paper122 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Optofluidic biomolecule sensors based on a-Si:H microrings embedded in silicon-glass microchannelsThe large-scale and low-cost fabrication of high sensitivity sensors for the real-time detection of biochemicals and molecular substances opens up new opportunities in the areas of bioanalytic screening and medical diagnostics. Planar integrated photonic resonators that can be fabricated with a low footprint, in spatial and wavelength multiplexed arrangements, and that enable integration with microfluidics on the wafer scale have emerged as a promising sensing platform for these application fields. We realized an optofluidic and label-free biosensor that is based on hydrogenated amorphous silicon microring resonators embedded in silicon/glass microfluidic channels for analyte injection and biomolecule immobilization. The optofluidic sensor merits for refractive index and biomolecule sensing are evaluated by sensitivity and detection limit simulations, whereas a proof of concept is demonstrated by real-time protein immobilization experiments of functionalized resonators.Publicationtype: Journal Article121 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Optofluidic a-Si:H-based photonic lab-on-chip with dispersion engineered resonance spectra(IEEE, 2017-01-11); ; ; ; We report on a lab-on-chip sensor system based on integrated-optical resonators. The photonic components were realized in CMOS-process compatible amorphous silicon and the microfluidic interface enabling directed analyte transport was fabricated with soft-lithography technology. The developed sensor features optical resonators with dispersion engineered resonance spectra (DERS) to match optical resonance peaks over a wavelength region of several free spectral ranges. Resonance shifts caused by changes in refractive index of the investigated analyte are tracked by red-shifting a reference spectrum through the thermo-optic effect using electrical micro-heaters. With the DERS preserving the unambiguousness of the direct proportional relation between resonance shift and necessary heating power, this sensing principle enables direct electronic readout of analyte property changes. The sensor system therefore reduces the number and the size of peripheral devices usually necessary for the analysis of integrated optical devices, resulting in a broader range of potential application scenarios.Publicationtype: Journal Article161 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Energy-efficient wavelength multiplexers based on hydrogenated amorphous silicon resonatorsOptical multiplexers are key components of modern data transmission systems that have evolved from long-haul fiber communication applications down to the photonic interconnect level on-chip, which demand high bandwidths and low-power photonic links with small footprint. We present compact, energy-efficient, and high-bandwidth optical add/drop multiplexers that are based on complementary metal-oxide-semiconductor (CMOS) backend-compatible hydrogenated amorphous silicon microring resonators. We study the manufacturing nonuniformity of the as-fabricated devices and analyze the static power consumption that is required to actively align the multiplexers to a 100-GHz grid by using state-of-the-art microheaters. The microring filter banks are in excellent agreement with the design and satisfy a good tradeoff between concurrent properties of high-data-rate capability, low filter loss, high channel isolation, and manufacturing uniformity, which facilitates the operation with low static power consumption. In addition, we demonstrate that it is possible to permanently correct the unavoidable fabrication imperfections and to arrange the individual wavelength channels by a postfabrication trimming method so that the static power is reduced by more than an order of magnitude and allows minimization of these parts of the overall power requirements of such photonic integrated circuits down to record low metrics of a few femtojoules per bit.Publicationtype: Journal ArticleScopus© Citations 12 296 362 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Label-free photonic biosensors fabricated with low-loss hydrogenated amorphous silicon resonatorsThe precise detection of chemicals and biomolecules is of great interest in the areas of biotechnology and medical diagnostics. Thus, there is a need for highly sensitive, small area, andlow-cost sensors. We fabricated and optically characterized hydrogenated amorphous silicon photonic resonators for label-free lab-on-chip biosensors. The sensing was performed with small-footprint microdisk and microring resonators that detect a refractive-index change via the evanescent electric field. Homogeneous sensing with NaCl and surface-sensing experiments with immobilized bovine serum albumin (BSA) were carried out. A sensitivity as high as 460 nm/RIU was measured for NaCl dissolved in deionized water for the disk, whereas about 50 nm/RIU was determined for the ring resonator. The intrinsic limits of detection were calculated to be 3.3 × 10-4 and 3.2 × 10-3 at 1550-nm wavelength. We measured the binding of BSA to functionalized ring resonators and found that molecular masses can be detected down to the clinically relevant femtogram regime. The detection and quantification of related analytes with hydrogenated amorphous silicon photonic sensors can be used in medical healthcare diagnostics like point-of-care-testing and biotechnological screening.Publicationtype: Journal ArticleScopus© Citations 22 304 393