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Of all publications in the section: 5
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Article
Kruk S., Weismann M., Bykov A. et al. ACS Photonics. 2015. Vol. 2. No. 8.

We study, both experimentally and theoretically, the second-order nonlinear response from resonant metasurfaces composed of metal–dielectric nanodisks. We demonstrate that by exciting the resonant optical modes of the composite nanoparticles we can achieve strong enhancement of the second-harmonic signal from the metasurface. By employing a multipole expansion method for the generated second-harmonic radiation, we show that the observed SHG enhancement is due to the magnetic dipolar and electric quadrupolar second-order nonlinear response of the metasurface.

Added: Nov 26, 2020
Article
Ikhsanov R., Babicheva V. E., Zhukovsky S. V. et al. ACS Photonics. 2015. Vol. 2. No. 8. P. 1039-1048.
We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of “transition absorption”, i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate photoemission rate and transition absorption for nanoparticles surrounded by various media with a broad range of permittivities and show that photoemission rate and transition absorption follow the same dependence on the permittivity. Thus, we conclude that transition absorption is responsible for the enhancement of photoemission in the surface scenario. We calculate the ratio of photoemission cross-section for a gold nanosphere embedded in different materials such as silicon, zinc oxide, and titanium dioxide. For the calculations, we include both surface and bulk mechanisms of photoemission, using quantum calculations for the former one and a three-step phenomenological approach for the latter one. By comparison of both mechanisms, we show that the role of surface mechanism in the total photoemission cannot be neglected, as it dominates in the near-infrared wavelength range. We also show that in order to increase the photoemission rate, one benefits from placing nanoparticles in materials with lower permittivity. Finally, we apply our results to the case of nanowires partially embedded in a semiconductor substrate, which is a practically relevant design for narrow-band photodetection. Summarizing these results, we show that the reported narrow-band photoemission increase can at least partially be attributed to the surface mechanism.
Added: Sep 27, 2015
Article
Moiseev E., Kryzhanovskaya N., Polubavkina Y. et al. ACS Photonics. 2017. Vol. 4. No. 2. P. 275-281.

Microdisk lasers demonstrate high performance and low threshold characteristics due to supporting of whispering gallery modes with a high quality factor. One of the challenging problems impeding some practical applications of whispering gallery mode lasers is that they have isotropic emission predominantly lying in the plane of the cavity. In this work, we present a novel method that provides both enhancement of the laser emission and modifies its directivity, making the vertical direction favorable. Electromagnetic energy outcouples from the cavity through the platinum-carbon plasmonic wire nanoantenna grown by electron-beam assisted deposition right up the side wall of the cavity. Evanescent field of whispering gallery mode excites surface plasmon polariton which propagates along the nanoantenna and scatters at its tip. We demonstrate 20× enhancement of the dominant mode intensity with 24 dB of side mode suppression increment without essential worsening of the Q-factor which remains over 3 × 104. The proposed approach of the efficient control over the spectrum, directivity, and emission efficiency from microdisk lasers could be very promising for many practical applications from telecommunication technologies to biosensing.

Added: Sep 30, 2020
Article
Melentiev P., Kalmykov A., Balykin V. ACS Photonics. 2019. Vol. 6. P. 1425-1433.

Due to losses in metals, the propagation length of the surface plasmon-polariton (SPP) waves on metal surfaces is small. This severely limits development of numerous applications of the SPP optics: in the near-infrared spectral region propagation length of SPP waves is no longer than 200 μm as for plane SPP waves and for all types of SPP waveguides. In this work, we show that the focusing of SPPs allows for the first time realizing open-type waveguide for SPP waves characterized by long distance of SPP effective propagation length up to 1 mm at a wavelength of 780 nm. We show that focused SPP waves in such a waveguide can be effectively excited by a 16 fs laser as well as be amplitude modulated within a bandwidth about 3.5 THz. The fast dynamics of the focused SPP waves is limited by the SPP group velocity dispersion. The large effective propagation length of the SPPs and its ultrahigh bandwidth open up new possibilities for using focused SPPs in different areas of plasmonics and photonics.

Added: Dec 20, 2019
Article
Нечепуренко И. А. ACS Photonics. 2018. Vol. 5. No. 12. P. 5038-5046.

A pulsed regime of short-cavity, heavily erbium-doped fiber lasers is of high interest for its possible applications in telecommunications and sensorics. Here, we demonstrate and compare these lasers in two configurations, a distributed feedback laser and a classic Fabry–Perot-type laser. We have managed to create lasers that function stably with cavities as small as 50 mm. Pulse properties such as amplitude, frequency, and duration are in a good agreement with our theoretical analysis, which takes into account spontaneous emission. We report the observation of the thermal switching effect, which consists in the pulsing regime changing to CW upon cooling the laser cavities down to liquid nitrogen temperature. We theoretically show that this effect may be explained by weakening of the up-conversion process responsible for the pulsed regime. The slowing of the up-conversion processes is due to the energy mismatch in this process, which is overcome by interaction with phonons. At low temperatures, the number of phonons decreases and pulsing switches off.

Added: Feb 7, 2019