14 research outputs found
Control of Spontanous Emission from Quantum Emitters Using Hyperbolic Metamaterial Substrates
Hyperbolic metamaterials (HMMs) are so named for possessing a hyperboloid-shaped dispersion which gives rise to a large photonic density of states. Quantum emitters placed inside or in the near-field of a HMM have been shown to exhibit strong enhancement of spontaneous emission due to the increase in available states. This thesis focuses on enhancing spontaneous emission of quantum emitters in optical frequencies by utilizing multilayered metal/dielectric composites that form these highly anisotropic metamaterials. In conjunction with the enhanced decay rate we experimentally demonstrate two methods for shaping and directing radiation trapped in the HMM into free space by employing a new class of artificial photonic media which we term a photonic hypercrystal. The ability to significantly enhance the spontaneous emission rate and control the directionality paves the way to practical applications using hyperbolic metamaterials such as sub-wavelength lasers, single-photon sources, and ultrafast light emitting diodes
Purcell Effect in the Stimulated and Spontaneous Emission Rates of Nanoscale Semiconductor Lasers
Nanoscale semiconductor lasers have been developed recently using either
metal, metallo-dielectric or photonic crystal nanocavities. While the
technology of nanolasers is steadily being deployed, their expected performance
for on-chip optical interconnects is still largely unknown due to a limited
understanding of some of their key features. Specifically, as the cavity size
is reduced with respect to the emission wavelength, the stimulated and the
spontaneous emission rates are modified, which is known as the Purcell effect
in the context of cavity quantum electrodynamics. This effect is expected to
have a major impact in the 'threshold-less' behavior of nanolasers and in their
modulation speed, but its role is poorly understood in practical laser
structures, characterized by significant homogeneous and inhomogeneous
broadening and by a complex spatial distribution of the active material and
cavity field. In this work, we investigate the role of Purcell effect in the
stimulated and spontaneous emission rates of semiconductor lasers taking into
account the carriers' spatial distribution in the volume of the active region
over a wide range of cavity dimensions and emitter/cavity linewidths, enabling
the detailed modeling of the static and dynamic characteristics of either
micro- or nano-scale lasers using single-mode rate-equations analysis. The
ultimate limits of scaling down these nanoscale light sources in terms of
Purcell enhancement and modulation speed are also discussed showing that the
ultrafast modulation properties predicted in nanolasers are a direct
consequence of the enhancement of the stimulated emission rate via reduction of
the mode volume.Comment: 12 pages, 5 figure
Recent advances in solid-state organic lasers
Organic solid-state lasers are reviewed, with a special emphasis on works
published during the last decade. Referring originally to dyes in solid-state
polymeric matrices, organic lasers also include the rich family of organic
semiconductors, paced by the rapid development of organic light emitting
diodes. Organic lasers are broadly tunable coherent sources are potentially
compact, convenient and manufactured at low-costs. In this review, we describe
the basic photophysics of the materials used as gain media in organic lasers
with a specific look at the distinctive feature of dyes and semiconductors. We
also outline the laser architectures used in state-of-the-art organic lasers
and the performances of these devices with regard to output power, lifetime,
and beam quality. A survey of the recent trends in the field is given,
highlighting the latest developments in terms of wavelength coverage,
wavelength agility, efficiency and compactness, or towards integrated low-cost
sources, with a special focus on the great challenges remaining for achieving
direct electrical pumping. Finally, we discuss the very recent demonstration of
new kinds of organic lasers based on polaritons or surface plasmons, which open
new and very promising routes in the field of organic nanophotonics
Control of Light-Matter Interaction in 2D Semiconductors
In this thesis we discuss the control of light matter interaction in low dimensional nanostructure cavity light confining structures. These structures have controllable dispersion properties through design which can be exploited to modify the interaction of light and matter. We will discuss two different types of light confining microcavities: a dielectric cavity and a metal cavity. The specific design of the cavity gives rise to the confinement of the electric field in the center where the nano-materials are placed. In this work, the main material was on the new class of two- dimensional semiconductors of transition metal dichalcogenides (TMDs). Due to the large binding energy and strong oscillator strength, in TMDs the strong coupling could be observed at room temperature. Specifically the valley polarization as an extra degree of freedom of the polaritons was demonstrated in the thesis. The realization of valley polaritons in two-dimensional semiconductor microcavities presents the first step towards engineering valley-polaritonic devices.
In the later of the thesis, we will also discuss the enhancement of the spontaneous emission of quantum emitters at optical frequencies by utilizing artificially designed photonic hypercrystal (PHC) and hyperbolic metamaterial (HMM). Here the large photon density of states (PDOS) in the hyperbolic media was exploited.The ability to significantly enhance the spontaneous emission rate and control the directionality give rise to the possibility of realizing the practical applications such as ultrafast light emitting diodes, sub-wavelength lasers and high resolution imaging
Half-Wave Dipolar Metal-Semiconductor Laser
Nano-scale lasers harnessing metallic plasmons hold promise across physical
sciences and industrial applications. Plasmons are categorized as surface
plasmon polaritons (SPP) and localized surface plasmons (LSP). While SPP has
gained popularity for nano-lasers by fitting a few cycles of SPP waves into
resonators, achieving LSP lasing in single nanoparticles remains an elusive
goal. Here, we highlight the equivalence of LSP and SPP within resonant systems
and present lasers oscillating in the lowest-order LSP or, equivalently,
half-cycle SPP. This diffraction-limited dipolar emitter is realized through
strong coupling of plasmonic oscillation in gold and dielectric resonance in
high-gain III-V semiconductor in the near infrared away from surface plasmon
frequencies. The resulting single-mode stimulated emission peak exhibits
linewidth Q factors over 50 at room temperature, with wide tunability spanning
from 1190 to 1460 nm determined by resonator sizes ranging from 190 to 280 nm.
A semiconductor laser model elucidates the temporal and spectral buildup
dynamics under optical pumping. Notably, linewidth Q values surpassing 250 are
attained from higher-order, isolated laser particles within live biological
cells. These results offer fresh perspectives in nanophotonics and indicate
promising opportunities for multiplexed biological applications