This review provides an insight into the recent developments of photonic crystal (PhC)-based devices for sensing and imaging, with a particular emphasis on biosensors. We focus on two main classes of ...devices, namely sensors based on PhC cavities and those on guided mode resonances (GMRs). This distinction is able to capture the richness of possibilities that PhCs are able to offer in this space. We present recent examples highlighting applications where PhCs can offer new capabilities, open up new applications or enable improved performance, with a clear emphasis on the different types of structures and photonic functions. We provide a critical comparison between cavity-based devices and GMR devices by highlighting strengths and weaknesses. We also compare PhC technologies and their sensing mechanism to surface plasmon resonance, microring resonators and integrated interferometric sensors.
Following the very promising results obtained by the solar cell community, metal halide perovskite materials are increasingly attracting the attention of other optoelectronics researchers, especially ...for light emission applications. Lasing with both engineered and self-assembled resonator structures, such as microcrystal networks, has now been successfully observed, with the low cost and the simple solution-based process being a particular attraction. The ultimate in simplicity, however, would be to observe lasing from a continuous thin film, which has not been reported yet. Here, we show random lasing action from such a simple perovskite layer. Our lasers work at room temperature; they are deposited on unpatterned glass substrates and they exhibit a minimum threshold value of 10 µJ/cm
. By carefully controlling the solution processing conditions, we can determine whether random lasing occurs or not, using identical precursors. A rather special feature is that some of the films exhibit single and dual mode lasing action, which is rarely observed in random lasers. Our work fully exploits the simplicity of the solution-based process and thereby adds an important capability into the emerging field of perovskite-based light emitters.
The monitoring of biomolecular interactions is a key requirement for the study of complex biological processes and the diagnosis of disease. Technologies that are capable of providing label-free, ...real-time insight into these interactions are of great value for the scientific and clinical communities. Greater understanding of biomolecular interactions alongside increased detection accuracy can be achieved using technology that can provide parallel information about multiple parameters of a single biomolecular process. For example, electro-optical techniques combine optical and electrochemical information to provide more accurate and detailed measurements that provide unique insights into molecular structure and function. Here, we present a comparison of the main methods for electro-optical biosensing, namely, electrochemical surface plasmon resonance (EC-SPR), electrochemical optical waveguide lightmode spectroscopy (EC-OWLS), and the recently reported silicon-based electrophotonic approach. The comparison considers different application spaces, such as the detection of low concentrations of biomolecules, integration, the tailoring of light-matter interaction for the understanding of biomolecular processes, and 2D imaging of biointeractions on a surface.
Abstract
Dielectric metasurfaces support resonances that are widely explored both for far-field wavefront shaping and for near-field sensing and imaging. Their design explores the interplay between ...localised and extended resonances, with a typical trade-off between Q-factor and light localisation; high Q-factors are desirable for refractive index sensing while localisation is desirable for imaging resolution. Here, we show that a dielectric metasurface consisting of a nanohole array in amorphous silicon provides a favourable trade-off between these requirements. We have designed and realised the metasurface to support two optical modes both with sharp Fano resonances that exhibit relatively high Q-factors and strong spatial confinement, thereby concurrently optimizing the device for both imaging and biochemical sensing. For the sensing application, we demonstrate a limit of detection (LOD) as low as 1 pg/ml for
Immunoglobulin G
(IgG); for resonant imaging, we demonstrate a spatial resolution below 1 µm and clearly resolve individual
E. coli
bacteria. The combined low LOD and high spatial resolution opens new opportunities for extending cellular studies into the realm of microbiology, e.g. for studying antimicrobial susceptibility.
Pure-quartic solitons Blanco-Redondo, Andrea; de Sterke, C Martijn; Martijn, de Sterke C ...
Nature communications,
01/2016, Letnik:
7, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Temporal optical solitons have been the subject of intense research due to their intriguing physics and applications in ultrafast optics and supercontinuum generation. Conventional bright optical ...solitons result from the interaction of anomalous group-velocity dispersion and self-phase modulation. Here we experimentally demonstrate a class of bright soliton arising purely from the interaction of negative fourth-order dispersion and self-phase modulation, which can occur even for normal group-velocity dispersion. We provide experimental and numerical evidence of shape-preserving propagation and flat temporal phase for the fundamental pure-quartic soliton and periodically modulated propagation for the higher-order pure-quartic solitons. We derive the approximate shape of the fundamental pure-quartic soliton and discover that is surprisingly Gaussian, exhibiting excellent agreement with our experimental observations. Our discovery, enabled by precise dispersion engineering, could find applications in communications, frequency combs and ultrafast lasers.
Many novel susceptibility tests are being developed to tackle the worldwide problem of antimicrobial resistance (AMR). The key driver behind these developments, that is the need to reduce the ...response time, requires an understanding of which bacterial characteristic needs to be monitored to provide a rapid and ideally universal signature of susceptibility. Many characteristics have already been studied, most notably bacterial growth, metabolism and motility. Here, we consider electrical impedance to directly access bacterial metabolism, which can be considered a fundamental indicator of bacterial viability. By studying the electrical response of individual bacteria to an antibiotic challenge, we detect antimicrobial action close to its biological limit. Specifically, we find that it takes 30–60 min to register significant changes in impedance for clinical concentrations of antibiotics, in line with other rapid indicators. Our findings suggest that 60 min is the fundamental lower limit of response time for a realistic susceptibility test at clinically relevant antibiotic concentrations.
•We introduce a microfluidic device capable of electrical impedance spectroscopy of single bacteria.•Electrical signatures of three different antibiotics on a few bacteria are measured within 60 minutes.•Detection is limited by the time of action of the antibiotics, suggesting a lower response time of ∼1 hour for practical susceptibility tests.
We present a systematic procedure for designing "flat bands" of photonic crystal waveguides for slow light propagation. The procedure aims to maximize the group index - bandwidth product by changing ...the position of the first two rows of holes of W1 line defect photonic crystal waveguides. A nearly constant group index - bandwidth product is achieved for group indices of 30-90 and as an example, we experimentally demonstrate flat band slow light with nearly constant group indices of 32.5, 44 and 49 over 14 nm, 11 nm and 9.5 nm bandwidth around 1550 nm, respectively.
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