Aims. Future astrophysics and cosmic microwave background space missions operating in the far-infrared to millimetre part of the spectrum will require very large arrays of ultra-sensitive detectors ...in combination with high multiplexing factors and efficient low-noise and low-power readout systems. We have developed a demonstrator system suitable for such applications. Methods. The system combines a 961 pixel imaging array based upon Microwave Kinetic Inductance Detectors (MKIDs) with a readout system capable of reading out all pixels simultaneously with only one readout cable pair and a single cryogenic amplifier. We evaluate, in a representative environment, the system performance in terms of sensitivity, dynamic range, optical efficiency, cosmic ray rejection, pixel-pixel crosstalk and overall yield at an observation centre frequency of 850 GHz and 20% fractional bandwidth. Results. The overall system has an excellent sensitivity, with an average detector sensitivity \hbox{$\mathrm{\langle NEP_{det}\rangle =3\times10^{-19}\;\WHz}$}⟨NEPdet⟩=3×10-19W/Hz measured using a thermal calibration source. At a loading power per pixel of 50 fW we demonstrate white, photon noise limited detector noise down to 300 mHz. The dynamic range would allow the detection of ~1 Jy bright sources within the field of view without tuning the readout of the detectors. The expected dead time due to cosmic ray interactions, when operated in an L2 or a similar far-Earth orbit, is found to be <4%. Additionally, the achieved pixel yield is 83% and the crosstalk between the pixels is <−30 dB. Conclusions. This demonstrates that MKID technology can provide multiplexing ratios on the order of a 1000 with state-of-the-art single pixel performance, and that the technology is now mature enough to be considered for future space based observatories and experiments.
Changes in the secondary and tertiary structure of DNA upon binding to silver, gold, and palladium nanoparticles (NPs) in solution were studied using UV spectroscopy, viscometry, dynamic light ...scattering, flow birefringence, and atomic force microscopy. A method for preparation of NP bioconjugates with DNA was developed. The enhancement of optical anisotropy of the macromolecule upon its contacts with metal NPs was detected. The effect of the formed structures on the persistence length of DNA and on the volume effects in the system was analyzed. A mechanism of NP formation upon the reduction of DNA-bound metal ions was proposed.
Photocatalytic glass-ceramics doped with metallic Ag, semiconductor AgBr, and hybrid metal-semiconductor Ag-AgBr nanostructures were synthesized
via
low-temperature Na
+
-Ag
+
ion exchange. The ...spectral features of the nanostructures in the silicate glass matrix as well as their photocatalytic performance were studied in detail. Glass-ceramics containing hybrid metal-semiconductor nanostructures were shown to possess one order of magnitude higher photocatalytic activity compared to their counterparts with metallic and semiconductor nanostructures. Hybrid metal-semiconductor nanostructures allow enhancement of the net density of photogenerated hot electrons.
Photocatalytic glass-ceramics with various nanostructures were obtained
via
Na
+
-Ag
+
ion exchange. Glass-ceramics with hybrid metal-semiconductor nanostructures possessed an order of magnitude higher photocatalytic activity.
•The magneto-optical response considerably increases due to the plasmon resonances.•In nested 2D nanostructures, the sign of polarization rotation can be inverted.•Due to the nested arrangement, the ...responses of can be strongly altered.
Nested square 2D lattice of gold nanospheres encased in a film of bismuth-substituted yttrium iron garnet (Bi:YIG) have been studied. Symmetry, structural and dielectric parameters of such nanostructures have been found to define the number of plasmon resonances and their spectral positions. As compared with a conventional film of Bi:YIG, the magneto-optical response of the studied nanostructures considerably increases due to the plasmon resonances, and the sign of polarization rotation is defined by a configuration of the localized near fields. Also, we demonstrate that, due to the nested arrangement, the optical and magneto-optical responses of the nanostructures can be strongly altered with a negligible change in their structural parameters.
We demonstrate the existence of a spectrally narrow localized surface state, the so-called optical Tamm state, at the interface between one-dimensional magnetophotonic and nonmagnetic photonic ...crystals. The state is spectrally located inside the photonic band gaps of each of the photonic crystals comprising this magnetophotonic structure. This state is associated with a sharp transmission peak through the sample and is responsible for the substantial enhancement of the Faraday rotation for the corresponding wavelength. The experimental results are in excellent agreement with the theoretical predictions.
The Bloch surface wave resonance (SWR) was visualized with the aid of plasmon absorption in a dielectric/metal/dielectric sandwich terminating a one-dimensional photonic crystal (PhC). An SWR peak in ...calculated spectra of such a plasmonic photonic crystal (PPhC) slab comprising a noble or base metal layer was demonstrated to be sensitive to a negligible variation of refractive index of a medium adjoining to the slab. The considered structure of PPhC slabs can be of practical importance because the metal layer is protected by a capping dielectric layer from contact with analytes and, consequently, from deterioration. We found that, in case of PPhC slabs, gold (the key element of the surface plasmon resonance-based biosensors) can be replaced by other metals. The PPhC-based sensors can be low-cost, reusable, and robust sensors having a sensitivity surpassing that of the known optical sensors.
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