65 research outputs found
A mini-module with built-in spacers for high-throughput ultrafiltration
Ultrafiltration membrane modules suffer from a permeate flow decrease arising
during filtration and caused by concentration polarization and fouling in,
e.g., fermentation broth purification. Such performance losses are frequently
mitigated by manipulating the hydrodynamic conditions at the membrane-fluid
interface using, e.g., mesh spacers acting as static mixers. This additional
element increases manufacturing complexity while improving mass transport in
general, yet accepting their known disadvantages such as less transport in dead
zones. However, the shape of such spacers is limited to the design of
commercially available spacer geometries. Here, we present a methodology to
design an industrially relevant mini-module with an optimized built-in 3D
spacer structure in a flat-sheet ultrafiltration membrane module to eliminate
the spacer as a separate part. Therefore, the built-in structures have been
conceptually implemented through an in-silico design in compliance with the
specifications for an injection molding process. Ten built-in structures were
investigated in a digital twin of the mini-module by 3D-CFD simulations to
select two options, which were then compared to the empty feed channel
regarding mass transfer. Subsequently, the simulated flux increase was
experimentally verified during bovine serum albumin (BSA) filtration. The new
built-in sinusoidal corrugation outperforms conventional mesh spacer inlays by
up to 30% higher permeation rates. The origin of these improvements is
correlated to the flow characteristics inside the mini-module as visualized
online and in-situ by low-field and high-field magnetic resonance imaging
velocimetry (flow-MRI) during pure water permeation
Nanothermoforming of hierarchical optical components utilizing shape memory polymers as active molds
Coherent terabit communications with microresonator Kerr frequency combs
Optical frequency combs enable coherent data transmission on hundreds of
wavelength channels and have the potential to revolutionize terabit
communications. Generation of Kerr combs in nonlinear integrated microcavities
represents a particularly promising option enabling line spacings of tens of
GHz, compliant with wavelength-division multiplexing (WDM) grids. However, Kerr
combs may exhibit strong phase noise and multiplet spectral lines, and this has
made high-speed data transmission impossible up to now. Recent work has shown
that systematic adjustment of pump conditions enables low phase-noise Kerr
combs with singlet spectral lines. Here we demonstrate that Kerr combs are
suited for coherent data transmission with advanced modulation formats that
pose stringent requirements on the spectral purity of the optical source. In a
first experiment, we encode a data stream of 392 Gbit/s on subsequent lines of
a Kerr comb using quadrature phase shift keying (QPSK) and 16-state quadrature
amplitude modulation (16QAM). A second experiment shows feedback-stabilization
of a Kerr comb and transmission of a 1.44 Tbit/s data stream over a distance of
up to 300 km. The results demonstrate that Kerr combs can meet the highly
demanding requirements of multi-terabit/s coherent communications and thus
offer a solution towards chip-scale terabit/s transceivers
High-speed, low drive-voltage silicon-organic hybrid modulator based on a binary-chromophore electro-optic material
We report on the hybrid integration of silicon-on-insulator slot waveguides with organic electro-optic materials. We investigate and compare a polymer composite, a dendron-based material, and a binary-chromophore organic glass (BCOG). A record-high in-device electro-optic coefficient of 230 pm/V is found for the BCOG approach resulting in silicon-organic hybrid Mach-Zehnder modulators that feature low UpL-products of down to 0.52 Vmm and support data rates of up to 40 Gbit/
Single-laser 32.5 Tbit/s Nyquist WDM transmission
We demonstrate 32.5 Tbit/s 16QAM Nyquist WDM transmission over a total length
of 227 km of SMF-28 without optical dispersion compensation. A number of 325
optical carriers are derived from a single laser and encoded with
dual-polarization 16QAM data using sinc-shaped Nyquist pulses. As we use no
guard bands, the carriers have a spacing of 12.5 GHz equal to the Nyquist
bandwidth of the data. We achieve a high net spectral efficiency of 6.4
bit/s/Hz using a software-defined transmitter which generates the electrical
modulator drive signals in real-time.Comment: (c) 2012 Optical Society of America. One print or electronic copy may
be made for personal use only. Systematic reproduction and distribution,
duplication of any material in this paper for a fee or for commercial
purposes, or modifications of the content of this paper are prohibite
40 GBd 16QAM signaling at 160 Gb/s in a silicon-organic hybrid modulator
We demonstrate for the first time generation of 16-state quadrature amplitude modulation (16QAM) signals at a symbol rate of 40 GBd using silicon-based modulators. Our devices exploit silicon-organic hybrid (SOH) integration, which combines silicon-on-insulator slot waveguides with electro-optic cladding materials to realize highly efficient phase shifters. The devices enable 16QAM signaling and quadrature phase shift keying (QPSK) at symbol rates of 40 GBd and 45 GBd, respectively, leading to line rates of up to 160 Gbit/s on a single wavelength and in a single polarization. This is the highest value demonstrated by a silicon-based device up to now. The energy consumption for 16QAM signaling amounts to less than 120 fJ/bit – one order of magnitude below that of conventional silicon photonic 16QAM modulators
Silicon-organic hybrid (SOH) integration and photonic multi-chip systems: Technologies for high-speed optical interconnects
Limitations of silicon photonics can be overcome by hybrid integration of silicon photonic or plasmonic circuits with organic materials or by photonic multi-chip systems. We give an overview on our recent progress regarding both silicon-organic hybrid (SOH) integration and multi-chip integration enabled by photonic wire bonding
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