The 2016 celebration of the 125th anniversary of the birth of Academician S I Vavilov, the outstanding physicist of the last century, provides an opportunity to compare what is going on today at the ...Russian Academy of Sciences (reforms, new members election, etc.) to the days long ago that preceded the foundation of the P N Lebedev Physical Institute (FIAN). The role of S I Vavilov and his academician colleagues in fighting bureaucracy and bureaucrats to create real academic science in our country is examined in this short paper.
Effective interaction of light with quantum emitters is important for the development of efficient high-frequency nanophotonic devices. One of the most attractive ways of solving this problem is the ...employment of nanopatch antennas (NPAs) with various efficient photon emitters. In the present study, we investigated the properties of the NPAs with different geometries involving a Ru(bpy)32+ complex (tris(2,2'-bipyridine) ruthenium(II) hexafluorophosphate) which was taken as a highly stable emitter. An increase in the radiation power of the metalorganic system was experimentally obtained. In particular, an increase in the photoluminescence intensity of the emitter was observed, and a significant reduction (down to 7 ns) in the lifetime of the excited states in the Ru-complex (with 'free' lifetime of about 850 ns) was demonstrated for an inhomogeneous 'aluminum-silver nanoparticle' system incorporating the Ru-complex. The increase in the spontaneous emission rate of Ru(bpy)32+ was attributed to the Purcell effect. The averaged values of the Purcell factors obtained for the emitter in the resonator with pentagonal and hexagonal silver nanoparticles were 100 and 120, respectively. It was shown that in an NPA with single vertically oriented emitters, the maximum values of the Purcell factors can be as high as 103. Also, radiation patterns were simulated showing that the radiation maximum is observed at an angle of about 50° to the surface of the nanoantenna. Luminescence enhancement factors for the studied types of NPAs were obtained both experimentally and theoretically.
Modern microchip-scale transceivers are capable of transmitting data at rates of the order of several terabits per second. In this regard, there is an urgent need to improve the interfaces connecting ...the chips and extend the bandpass of the interconnections. We use an approach combining silicon nitride nanophotonic circuits with 3D polymer waveguides fabricated by direct laser writing, which can be used as photonic interconnections or photonic wire bonds (PWB). These structures are designed, simulated, fabricated, and optimized for better light transmission at the telecommunication wavelength. An important part of this work is the study of the telecom signal transmission in a 3D polymer waveguide connecting two silicon nitride facing tapers. Two cases are considered: the tapers are one opposite the other or misaligned. Initially, the PWB shape was chosen to be Gaussian and then optimized: the top was circle-shaped and with the lower part still being Gaussian. Transmission losses were measured for both types of waveguides with different shapes. The idea of an optical multi-level crossing for photonic integrated circuits is also suggested as a solution to the problem of interconnections within a single chip.
Hybrid materials containing organic components and colloidal semiconductor nanocrystals of various shapes, sizes and structures of shells are widely used for developing novel nanophotonic and ...optoelectronic devices. Unique optical properties of semiconductor nanocrystals, which can be effectively, controlled using quantum confinement effects, as well as the possibility to synthesize multi-layered structures of various sizes and shapes with different relative dimensions of the core and the shell draw enduring interest. At the same time, organic semiconductor materials are less expensive than their inorganic counterparts are.
Two-photon laser polymerization (TPP) is a state-of-the-art technology that allows for the submicron-resolution printing of freeform 3D objects to be harnessed in various applications, including ...physics, biology, medicine, and materials science. The TPP is based on using photosensitive polymeric materials that impose restrictions on the minimum feature size and limit the functionality of printed structures within the capabilities of polymers. One of the promising yet insufficiently studied methods for overcoming these limitations is pyrolysis–high-temperature annealing of polymer objects in an inert atmosphere. It may allow both to decrease the size of the objects and modify their chemical composition. Here, we compare the effect of pyrolysis on solid objects being tens of micrometers in size printed by TPP from three commercially available photoresists: IP-Dip, OrmoComp, and SZ2080. For the annealing temperatures of 450°C and 690°C in an argon atmosphere, we assessed the changes in size, chemical composition, and adhesion to the silicon wafer substrate. Our data may be promising for developing pyrolysis as a standard post-processing method for structures created via TPP technology.
Luminescence properties of water-soluble hybrid associates of semiconductor colloidal CdS quantum dots (QDs) with average size of 2.5nm, 3.2nm, 4.2nm and J-aggregates of ...3,3′-di-(γ-sulfopropyl)-4,4′,5,5′-dibenzo-9-ethylthiacarbocyanine betaine pyridinium salt (Dye) in gelatin were investigated using the methods of absorption, steady-state and time-resolved luminescence spectroscopy. The decrease in luminescence intensity of CdS QDs and increase in luminescence intensity of Dye J-aggregates were detected with increasing of Dye concentration. It was shown that curves of luminescence decay of CdS QDs are non-exponential. The decreasing of luminescence lifetime of CdS QDs with increasing of Dye J-aggregates concentration was observed. It was concluded that dynamic quenching due to non-radiative resonance energy transfer takes place. It was shown that overlap integral between luminescence spectra of CdS QDs and absorption spectra of Dye J-aggregates increases with the increase of average diameter of CdS QDs and luminescence decay of CdS QDs is accelerated. Energy transfer efficiency for all three sizes of QDs was more than 31%.
Abstract
Color centers in nanodiamonds are promising candidates for the creation of high-speed sources of single photons without blinking and degradation. Color centers in HPHT nanodiamonds have been ...investigated. The luminescence decay curves of color centers have been measured. Second order correlation functions were measured for nanodiamonds with sizes from 50 nm to 250 nm. Conclusions about the energy structure of color centers were made based on the correlation functions.
In the last few years, a great interest has attracted structures called plasmonic nanopatch antennas (PNA). As a rule, the nanopatch antenna consists of a metallic nanoparticle located above the ...metal surface and separated from it by a layer of dielectric. In PNA, significant amplification of local electromagnetic fields is possible, which allows reaching high densities of the local electronic states of the emitter placed inside the PNA. In such structures it is possible to achieve the Purcell factor of the order of 103, which gives an advantage to PNA in comparison with dielectric one, where the Purcell factor is several units. High Purcell factor allows to create sources of single photons with a frequency of up to 100 GHz. In this paper, calculations of plasmon resonance dependences on various structure parameters on the example of PNA with a triangular silver nanoprism are carried out.
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•Hybrid organic/inorganic light-emitting-diode based on CdSe nanoplatelets is designed.•Nanoplatelets have average thickness d=1.5nm and lateral sizes a=15nm and b=47nm.•Our device ...operates at the wavelength of 515nm with the turn-on voltage of 5.5V.•CdSe nanoplatelets are potentially attractive for fabricating LEDs with pure color.
We report on the fabrication of a hybrid light-emitting-diode based on colloidal semiconductor CdSe nanoplatelets as emitters and organic TAZ 3-(Biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole and TPD N, N′-bis (3-methylphenyl)-N, N′-bis (phenyl)-benzidine materials as the electron and hole transporting layers. Electroluminescent and current–voltage characteristics of the developed hybrid device with the turn-on voltage of 5.5V and the radiation wavelength of 515nm have been obtained. Semiconductor nanoplatelets like CdSe are attractive for the fabrication of hybrid LEDs with low operating voltages, spectrally pure color and short-wavelength electroluminescence, which is required for RGB devices.
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