101 research outputs found
Recommended from our members
Miniaturization of optical spectrometers
Spectroscopic analysis is one of the most widely used analytical tools across both scientific research and industry. Whilst laboratory bench-top spectrometer systems offer superlative resolution and spectral range, their miniaturization is crucial for applications where portability is paramount, or in-situ measurements must be made. Advancement in this field over the last three decades is now yielding microspectrometers with performance and footprint near those viable for lab-on-a-chip systems, smartphones and other consumer technologies. In this review, we briefly summarize the technologies that have emerged toward achieving these aims - including miniaturized dispersive optics, narrowband filter systems, Fourier transform interferometers and reconstructive microspectrometers - and discuss the challenges associated with improving spectral resolution while device dimensions shrink ever further.EPSRC: EP/L016087/1
National Natural Science Foundation of China (51706141, 51976122
Functional inks of graphene, metal dichalcogenides and black phosphorus for photonics and (opto) electronics
We discuss the emerging role of solution processing and functional ink formulation in the fabrication of devices
based on two dimensional (2d) materials. By drawing on examples from our research, we show that these inks
allow 2d materials to be exploited in a wide variety of applications, including in photonics and (opto)electronics.
Keywords: Graphene, Transition Metal Dichalcogenides, TMDs, Black Phosphorous, Phosphorene, Functional
Inks, 2d Materials, Inkjet Printing, Ultrafast Lasers, Flexible Electronic
Surfactant-aided exfoliation of molydenum disulphide for ultrafast pulse generation through edge-state saturable absorption
We use liquid phase exfoliation to produce dispersions of molybdenum
disulphide (MoS2) nanoflakes in aqueous surfactant solutions. The chemical
structures of the bile salt surfactants play a crucial role in the exfoliation
and stabilization of MoS2. The resultant MoS2 dispersions are heavily enriched
in single and few (<6) layer flakes with large edge to surface area ratio. We
use the dispersions to fabricate free-standing polymer composite wide-band
saturable absorbers to develop mode-locked and Q- switched fibre lasers,
tunable from 1535-1565 and 1030-1070 nm, respectively. We attribute this
sub-bandgap optical absorption and its nonlinear saturation behaviour to
edge-mediated states introduced within the material band-gap of the exfoliated
MoS2 nanoflakes.Comment: 6 pages, 5 figure
Miniaturized Computational Photonic Molecule Spectrometer
Miniaturized spectrometry system is playing an essential role for materials
analysis in the development of in-situ or portable sensing platforms across
research and industry. However, there unavoidably exists trade-offs between the
resolution and operation bandwidth as the device scale down. Here, we report an
extreme miniaturized computational photonic molecule (PM) spectrometer
utilizing the diverse spectral characteristics and mode-hybridization effect of
split eigenfrequencies and super-modes, which effectively eliminates the
inherent periodicity and expands operation bandwidth with ultra-high spectral
resolution. These results of dynamic control of the frequency, amplitude, and
phase of photons in the photonic multi-atomic systems, pave the way to the
development of benchtop sensing platforms for applications previously
unfeasible due to resolution-bandwidth-footprint limitations, such as in gas
sensing or nanoscale biomedical sensing
Evanescent-wave coupled right angled buried waveguide: Applications in carbon nanotube mode-locking
In this paper we present a simple but powerful subgraph sampling primitive
that is applicable in a variety of computational models including dynamic graph
streams (where the input graph is defined by a sequence of edge/hyperedge
insertions and deletions) and distributed systems such as MapReduce. In the
case of dynamic graph streams, we use this primitive to prove the following
results:
-- Matching: First, there exists an space algorithm that
returns an exact maximum matching on the assumption the cardinality is at most
. The best previous algorithm used space where is the
number of vertices in the graph and we prove our result is optimal up to
logarithmic factors. Our algorithm has update time. Second,
there exists an space algorithm that returns an
-approximation for matchings of arbitrary size. (Assadi et al. (2015)
showed that this was optimal and independently and concurrently established the
same upper bound.) We generalize both results for weighted matching. Third,
there exists an space algorithm that returns a constant
approximation in graphs with bounded arboricity.
-- Vertex Cover and Hitting Set: There exists an space
algorithm that solves the minimum hitting set problem where is the
cardinality of the input sets and is an upper bound on the size of the
minimum hitting set. We prove this is optimal up to logarithmic factors. Our
algorithm has update time. The case corresponds to minimum
vertex cover.
Finally, we consider a larger family of parameterized problems (including
-matching, disjoint paths, vertex coloring among others) for which our
subgraph sampling primitive yields fast, small-space dynamic graph stream
algorithms. We then show lower bounds for natural problems outside this family
Real-time, noise and drift resilient formaldehyde sensing at room temperature with aerogel filaments
Formaldehyde, a known human carcinogen, is a common indoor air pollutant.
However, its real-time and selective recognition from interfering gases remains
challenging, especially for low-power sensors suffering from noise and baseline
drift. We report a fully 3D-printed quantum dot/graphene-based aerogel sensor
for highly sensitive and real-time recognition of formaldehyde at room
temperature. By optimising the morphology and doping of the printed structures,
we achieve a record-high response of 15.23 percent for 1 parts-per-million
formaldehyde and an ultralow detection limit of 8.02 parts-per-billion
consuming only 130 uW power. Based on measured dynamic response snapshots, we
also develop an intelligent computational algorithm for robust and accurate
detection in real time despite simulated substantial noise and baseline drift,
hitherto unachievable for room-temperature sensors. Our framework in combining
materials engineering, structural design and computational algorithm to capture
dynamic response offers unprecedented real-time identification capabilities of
formaldehyde and other volatile organic compounds at room temperature.Comment: Main manuscript: 21 pages, 5 figure. Supplementary: 21 pages. 13
Figures, 2 tabl
Recommended from our members
Conformal Printing of Graphene for Single- and Multilayered Devices onto Arbitrarily Shaped 3D Surfaces
Printing has drawn a lot of attention as a means of low per-unit cost and high throughput patterning of graphene inks for scaled-up thin-form factor device manufacturing. However, traditional printing processes require a flat surface and are incapable of achieving patterning on to 3D objects. Here, we present a conformal printing method to achieve functional graphene-based patterns on to arbitrarily-shaped surfaces. Using experimental design, we formulate a water-insoluble graphene ink with optimum conductivity. We then print single and multi-layered electrically functional structures on to a sacrificial layer using conventional screen printing. The print is then floated on water, allowing the dissolution of the sacrificial layer, while retaining the functional patterns. The single and multilayer patterns can then be directly transferred on to arbitrarily-shaped 3D objects without requiring any post deposition processing. Using this technique, we demonstrate conformal printing of single and multilayer functional devices that include joule heaters, resistive deformation sensors and proximity sensors on hard, flexible and soft substrates, such as glass, latex, thermoplastics, textiles, and even candies and marshmallows. Our simple strategy offers great promises to add new device and sensing functionalities to previously inert 3D surfaces.EPSRC (EP/L016087/1)
Graphene Flagshi
Wavelength tunable soliton rains in a nanotube-mode locked Tm-doped fiber laser
We report soliton rains in a tunable Tm-doped fiber laser mode locked by carbon nanotubes. We also detect their second- and third-harmonics. We achieve a tunability of over 56 nm, from 1877 to 1933 nm, by introducing a polarization-maintaining isolator and two in-line polarization controllers. This makes our system promising as a tunable filter for ultrafast spectroscopy.We acknowledge funding from ERC Grant Hetero2D, EPSRC Grants Nos. EP/L016087/1, EP/K017144/1, EP/K01711X/1 and the China Scholarship Council
Recommended from our members
Functional inks and printing of two-dimensional materials.
Graphene and related two-dimensional materials provide an ideal platform for next generation disruptive technologies and applications. Exploiting these solution-processed two-dimensional materials in printing can accelerate this development by allowing additive patterning on both rigid and conformable substrates for flexible device design and large-scale, high-speed, cost-effective manufacturing. In this review, we summarise the current progress on ink formulation of two-dimensional materials and the printable applications enabled by them. We also present our perspectives on their research and technological future prospects
- …