The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this paper we show the characterization of erbium-doped fibers, doing special emphasis on the study of the noise figure. The signal gain and OSNR has been measured for a set of EDF's lengths and pump powers, for future optimization of remotely pumped amplification in PONs. The NF is obtained form the set of measurements and the importance of usually disregarded terms of more general noise figure...
We have demonstrated an efficient nonresonant optical pumping scheme for high-Q scar modes in a two-dimensional quadrupole-deformed microlaser. We could obtain the dependence of pumping efficiency on the pumping angle from the cavity-modified fluorescence and from the measurement of threshold pump, which is inversely proportional to the pumping efficiency. Up to three-fold enhancement in the pumping...
We observed whispering gallery resonances (WGMs) in semiconductor micropillars by employing geometry in which both excitation and collection of emission is in a direction normal to the sidewall surface of the pillars. The spectral positions of the peaks are found to be in a good agreement with the results of numerical modeling performed by finite difference time domain technique. The quality factors...
We found alternate oscillations in AlGaAs/GaAs single-quantum-well (SQW) quasi-stadium laser diodes (QSLD). The alternate oscillations in QSLD can be well explained by the interactions of two different cavity modes due to the geometrical symmetry of QSLD. Unlike the alternate oscillations in semiconductor ring lasers that need the waveguides to extract the light signals, the alternate oscillation...
We have presented two contactless modes of electromodulation spectroscopy as tools for detailed nondestructive characterization of low dimensional semiconductor device structures. Several examples have been shown for different solutions of the laser structures for applications in 1.3 - 1.55 mum telecommunication range. The ways for determining their fundamental properties which are related then to...
Static cross gain saturation and dynamical small signal cross gain modulation are experimentally and theoretically investigated in order to judge the multi wavelength amplification capability of quantum dot semiconductor optical amplifiers (QD SOA). The measurements reveal the carriers in the excited states of the QDs to act as an effective reservoir, where QDs of different sizes participate in the...
Business uptake of IP-centric services has been strong and necessitates reliable, highly-available, high-quality Internet access. Real time services such as mission-critical broadcast video, video conferencing and voice over IP (VoIP) have low tolerance for short-term network outages. However, applications like bulk data transfer maybe much more resistant to such events. Many different network resilience...
The path computation element (PCE) framework provides functions and protocol extensions to address the computation of paths that span multiple routing areas or administrative domains in support of traffic engineering (TE) in multi-protocol label switching (MPLS) or generalized MPLS (GMPLS) networks. A PCE node typically resides at the domain or area border and is capable of computing optimal/diverse...
In this paper a multi-domain optical service environment is envisioned to demonstrate the role of the distributed control plane and management processes based on different standardization approaches. Emerging reliability requirements are discussed and the performance of optical networks is investigated by simulations on several control and/or management failure cases. The simulation results are extended...
We review recent progress in fabrication, characterization, and applications of ultra-high-Q crystalline whispering gallery mode (WGM) resonators. We report on the experimental observations of power-dependent, non-exponential decay of light stored in WGMs caused by stimulated Raman scattering in the resonator host material. We show that a proper thermal annealing leads to a significant increase of...
The efficiency of optical transport is studied in one-dimensional (ID) chains and in 3D lattices of coupled microspheres with ~1-3% size disorder. To couple light into such structures we used sources of light formed by dye-doped fluorescent microspheres. Using techniques of spatially resolved scattering spectroscopy we observed large propagation losses (~ 3 dB per sphere) along the chain at the frequencies...
We employ a focused laser beam both as an optical probe and as a tool to tune in situ the spectral position of modes of semiconductor optical microcavities containing quantum dots (QDs) as emitters. Laser-heating of a microcavity placed inside a cryostat is used either to locally enhance the refractive index or to controllably desorbs cryogettered gases. The latter approach allows us to controllably...
We report a demonstration of lasing in a two-dimensional (2D) microcavity which is a semiconductor diode structure with a stadium shape finely formed by reactive-ion-etching technique and pumped by electric current injection. The laser exhibits output over a wide angle, although the fundamental lasing modes have highly complex wave structures which do not correspond to any simple set of rays inside...
We have numerically investigated oscillatory lasing modes in a coupled circular microcavity laser by solving the Schrodinger-Bloch equation with a nonlinear interaction between the light field and the lasing medium. Uniform pumping in the lasing process generates some special patterns as stationary ones, and the patterns are repeatedly shown during the lasing process. In this case, the patterns may...
The far-field emission pattern of a two-dimensional circular microresonator with a point scatterer inside, at some distance away from the centre, is investigated theoretically. We demonstrate that the presence of the scatterer leads to significant enhancement in the directionality of the outgoing light in comparison with whispering gallery modes of a circular resonator without scatterer. Numerical...
Lasing properties of a circular dielectric microdisk laser are investigated. We find the possibility of directional output emissions based on a triangular shaped mode structure which can be constructed by superposition of a few whispering gallery modes. We also find that the directionality of emission beams is enhanced by selectively applied external pumping.
We present whispering-gallery mode terahertz quantum-cascade lasers with either "single-mode" or "double- mode" emission depending on the rotational symmetry of such resonators. Strong mode confinement in the growth and in-plane directions are provided by a double-plasmon waveguide and due to the strong impedance mismatch between the gain material and air. These ultra-compact devices...
The characteristics of quasi-bound states of a highly deformed microcavity were investigated in both theory and experiment. Five distinct mode groups were observed with cavity quality factors different by several orders of magnitude in the range of 104 - 106. Consistently they had quite different intracavity mode distributions. However, their far-field emission patterns were found to be almost identical,...
New services and high bandwidth demanding applications will dramatically change the operator's requirements with respect to future network architectures and topologies. The advent of bandwidth-intensive video applications will stimulate the design of high throughput and flexible network architectures. In this network evolution All-optical Label Swapping (AOLS) can play a key role. AOLS is a key functional...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.