The main achievement of the modern plasmonics is the concentration of light into nanospots that are much smaller than the wavelength. Nanospot concentration is beneficial for various applications: biomedical imaging and sensing, optical microscopy with single-molecule resolution, heat assisted magnetic recording (HAMR), QED studies, nanolasing, etc. Until now, plasmonic metal nanoantennae, sub-wavelength apertures or metallic near field concentrators (NFCs) are used for this purpose. The main advantage of the metal NFC is their capabilities to localize plasmonic modes, which can be excited by the incident transverse em wave. However, the metal NFCs have large optic loss so we propose a novel all-dielectric NFC, which allows focusing the light into a sub-wavelength hot nanospot, without the dissipative loss. The detrimental dephasing and thermal effects almost vanishes in the dielectric NFC opening new opportunities in the magnetic recording and quantum plasmonics. The ability to concentrate light is important not only to fundamental physics studies, but also to practical device applications. For example, microcavities can force the atoms or quantum dots to emit spontaneous photons in a desired direction or can provide an environment, where dissipative mechanisms such as spontaneous emission are overcome. The electric field is much enhanced in the proposed new device at the vertex of the dielectric beak, which is attached to the tablet dielectric resonator. The resonator in turn is pumped through the plane waveguide. The electric field is enhanced due to longitudinal polarization of the beak vertex, which is excited by em field of the pumped resonator.
Plasmon nanolasers, also known as SPASERs, were suggested by Bergman and Stockman in 2003. Quantum plasmonics attract much attention in recent years due to the numerous potential applications in the plasmonics. We consider thermal effects in the metal nanoresonator immersed in the active, laser medium. The size of the resonator is much less than the wavelength. The plasmon field inside the nanoresonator operates as a quantum object. Due to the nanosize of the resonator, the internal plasmon electric field is about the atomic field even for few plasmon quants. The coupling between the plasmon field and plasmon resonator is anomalous strong. We develop the quantum dynamics of the plasmon field and show that the SPASER may be the subject of thermal instability. The loss in SPASER increases with increasing the temperature when the average number of the plasmons is maintained at the stationary level. Therefore, the heat generation increases with increasing the temperature. This positive feedback results in the thermal instability. When the energy, accumulated in the plasmon nanoresonator, exceeds the instability threshold the temperature increases exponentially. We find the increment of the temperature growth and lifetime as function of the loss in metal and the structure of the plasmon resonator. We consider how the thermal instability influences the luminescence and find how the lasing threshold is changed. The coherence of the light emitted by the plasmon laser is also considered. The thermal stability of the nanolaser is crucial for any practical application.
The quantum-mechanical and thermal phenomena in the plasmonic nanoparticle and resonator are investigated. We develop quantum plasmonics by quantizing the collective electron motion in the surface plasmon. The operator of the electric field inside the metal nanoparticle is found. Thus obtained quantum electric field is anomalous large even for few plasmon quanta. The strong electric field, which value is comparable with the atomic field, results in huge electric current and overheating the metal nanoparticle when it operates as a resonator for the plasmon laser (SPASER). It is shown the overheating thermal instability can explode the particle.
Quantum-mechanical theory of the plasmon nanoresonator laser is presented. The Hamiltonian equations of motion are obtained for the plasmon field in the time domain. Then the plasmon field is quantized to develop the quantum plasmonics (QP). QP equations are solved and dynamics of the plasmon laser is obtained. We show that the plasmon laser is essentially thresholdless device in the nanosize limit, which radiation is coherent regardless of the pumping rate. We obtain the statistics of quanta, intensity, spectrum and linewidth of the radiation. Theory can also be applied to the usual photonic microlasers, metal-dielectric lasers and other small cavity devices.
KEYWORDS: Signal to noise ratio, Sensors, Telecommunications, Free space optical communications, Receivers, Digital signal processing, Optical tracking, Fiber couplers, Beam splitters, Retroreflectors
For Free Space Optical Communication (FSOC) systems, employed on moving platform or communicating
with a moving remote terminal, the quality of the communication channel strongly depends upon the tracking
performance. In these systems quadrant Position Sensitive Detectors (PSD) are commonly used for beam tracking.
This paper presents the results of significantly improved performance in acquisition and tracking of the FSOC system
using a custom made 8-segments PSD and minimizing the tracking spot size on the detector.
We consider plasmonic nanoantennas immersed in active host medium. Specifically shaped metal nanoantennas can
exhibit strong magnetic properties in the optical spectral range due to the excitation of Magnetic Resonance Plasmons
(MRP). A case when a metamaterial comprising such nanoantennas can demonstrate both "left-handiness" and negative
permeability in the optical range is considered. We show that high losses predicted for optical "left-handed" materials
can be compensated in the gain medium. Gains required to achieve local generation in such magnetic active
metamaterials are calculated for real metals
Implementation of long-range laser communication systems holds great promise for high-bandwidth applications. They are viewed as a technology that in the nearest future will handle most of the "last mile" communication traffic for the individual subscribers, corporate offices, military, and possibly deep space probes. Indeed, lasers allow for concentration of energy within tightly focused beams and narrow spectral interval, thus offering high throughput, information security, weight and size of components and power requirements that could not be matched by RF systems. However, the advantages of optical communication systems come in the same package with several major challenges. In particular, high data rates should be complemented by high-precision wide-bandwidth position control of a laser beam. In many applications the ability to maintain a link is affected by the complex maneuvers performed by mobile communication platforms, resident vibrations, and atmospheric effects. The search for the most effective and reliable way to shape and steer the laser beam is an on-going effort. This paper is focused on the application of acousto-optic technology as an alternative to electro-mechanical devices. With realization that an acousto-optic Bragg cell is only a component of the entire communication system, which should perform complex tasks of acquisition, pointing, and tracking of the remote terminal, we present an attempt to consider this problem from the "systems" point of view.
Interactive numerical simulator, based on MATLAB/SIMULINK platform, for virtual experimentation and optimization of frequency tunable optically pumped dimer laser has been created. Nonperturbative theory considering features of quantum coherence and interference effects at Doppler broadened transitions under two strong driving fields accounting for collisions and other kinetic processes in vapor-gas mixture as well as for propagation effects in optically thick medium is developed. The results are in good agreement with real experiments.
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