We study the strong coupling of dye molecules to surface plasmons polaritons of thin silver films. The dispersion splits into three branches and demonstrates avoided crossing, characteristic of strong coupling. The dispersion is further modified, when gain is introduced, by strongly pumping the dye molecules. In a series of complementary experiments, we also show that dye molecules can be strongly coupled to localized plasmons modes of rough silver films and also multilayered hyperbolic metamaterials. Our preliminary results could pave the way for a new class of hybrid plasmonic materials and metamaterials.
The behavior of spontaneous emission of emitters embedded inside metamaterials with hyperbolic dispersion has
been investigated. A simple technique has been developed to fabricate lamellar metal-dielectric hyperbolic
metamaterials on substrates which can be flat, flexible or curvilinear in geometry. Moreover, this method opens up the
possibility of functionalizing the dielectric layers by dye molecules. Utilizing this technique, we study the spontaneous
emission kinetics of emitters placed either on top, or embedded inside hyperbolic metamaterials. While we observe a
reduction in the radiative lifetimes in both cases, owing to the singularity in the density of photonic states, the effect is
much stronger when the dye molecules are inside the metamaterial, rather than on its surface.
In this work, we report the substantial compensation of loss of propagating SPPs at the interface between silver film and
optically pumped polymer with dye. The large magnitude of the effect, nearly threefold change of the reflectivity,
enables a variety of applications of "active" nanoplasmonics. In order to quantify the observed phenomenon, we have
extended the theoretical formalism relating the reflectivity in ATR experiment and the SPP propagation length to the
case of active dielectric media.
We have demonstrated that an addition of highly concentrated rhodamine 6G chloride dye to the PMMA film adjacent to
a silver film causes three-fold reduction of the imaginary part of the dielectric constant of Ag (absorption loss in metal)
and 30% elongation of the propagation length of surface plasmon polaritons (SPP). The possibility to elongate the SPP
propagation length without optical gain opens a new technological dimension to low-loss nanoplasmonics.
We discuss major factors responsible for obtaining transparent Nd3+:YAG ceramic, a prospective material for laser
applications. The relationship between the properties of starting nanopowders and the transmittance of specimens
sintered at the different "ramp-soak" conditions was established by means of spectroscopic, structural, and electronic
microscopy studies. It was found, that sample's transmittance (in some cases) depends on the duration of the holding
time at the sintering stage. This result is promising for obtaining laser quality materials. It also contributes to basic
understanding of the processes underlying fabrication of transparent laser ceramic.
We demonstrate first anti-Stokes laser in which only one pumping photon is required to produce one higher-energy emission photon. The difference of energy is drawn from phonons. This regime is realized in GaAs random laser. We also propose a laser system based on an anti-Stokes laser, which can be pumped by heat only. The temperature of the heater does not need to be high. The heat pumping energy (at practically no cost) can be provided via thermal contact of the laser element with an ambient environment, such as atmosphere, ocean, ground, etc.
Stimulated emission can be obtained in small volumes of scattering laser materials without cavity or any special optical design. Such sources of stimulated emission are known as random lasers. In random lasers, amplifying laser medium provides for gain, and scatterers (powder particles, air gaps between particles, etc.) provide for stimulated emission feedback. Above certain threshold pumping energy, the emission characteristics of random lasers change dramatically: the emission spectrum collapses to one or several narrow lines and one or several short emission pulses appear in response to a relatively long pumping pulse. Solid-state random lasers based on rare-earth doped dielectrics, dielectrics with color centers, semiconductors, scattering polymers, etc., offer challenging and not yet completely understood physics as well as promising applications, including express testing of laser materials, identification, and information processing. The focus of our presentation is on optically pumped neodymium random lasers. In particular, we discuss the dependence of the photon mean free path lt, the threshold energy density Eth/S and the slope efficiency in neodymium random lasers as a function of the mean particles size s. The experimental results are compared with the predictions of the developed models.
Stimulated emission in Nd0.5La0.5Al3(BO3)4 ceramic random laser was studied at different diameters of the pumped spot d. The developed heuristic model adequately describes the dependence of threshold pumping energy density versus d at d greater or equal to 150 micrometer. At small pumping beam diameter (less than 100 micrometer), very bright and strongly localized emission spot was observed in the center of the pumped area. The spectrum of the bright-spot emission appeared to be similar to that of 'continuum wave' light sources.