Enhanced light outcoupling in microdisk lasers via Si spherical nanoantennas
High-index dielectric (Si) nanoantennas providing outcoupling of light from InAs/Ga(Al)As quantum dot (QD) microdisk lasers have been designed. The spatial distribution of light emitted from optically pumped QD microdisk lasers with a single Si spherical nanoantenna placed on the top surface of the microdisk was studied experimentally by confocal optical microscopy. Dependences of the emission intensity on the size and position of the Si nanoan- tenna were investigated. It was found that the laser mode to be outcoupled can be selected by choosing the nanosphere position with respect to the mode electromagnetic field maximum. Optimization of the Si nanoantenna parameters resulted in a 23-fold increase of the emission intensity at the location of the Si nanoantenna (whereas the total intensity enhanced 4 times) compared to the emission intensity from the initial microdisk laser without significant deterio- ration of the resonator quality factor.
High-performance injection microdisk (MD) lasers grown on Si substrate are demonstrated for the first time, to the best of our knowledge. Continuous-wave (CW) lasing in microlasers with diameters from 14 to 30 μm is achieved at room temperature. The minimal threshold current density of 600 A/cm2600 A/cm2 (room temperature, CW regime, heatsink-free uncooled operation) is comparable to that of high-quality MD lasers on GaAs substrates. Microlasers on silicon emit in the wavelength range of 1320–1350 nm via the ground state transition of InAs/InGaAs/GaAs quantum dots. The high stability of the lasing wavelength (𝑑𝜆/𝑑𝐼=0.1 nm/mAdλ/dI=0.1 nm/mA) and the low specific thermal resistance of 4×10−3°C×cm2/W4×10−3°C×cm2/W are demonstrated.
Lasers based on semiconductor whispering gallery mode (WGM) resonators represent a perfect platform for active small footprint high-sensitive devices for biodetection. Biochemical samples typically require aqueous solution, and the resonator should be placed into a cuvette with water or in a microfluidic chip. The characteristics of modern semiconductor WGM lasers with an active region based on InAs/InGaAs quantum dots (QDs) make them promising for creating compact highly sensitive devices for biodetection. Deep localization of carriers in InAs/InGaAs QDs and suppressed lateral migration helps us to obtain room-temperature lasing in microdisk lasers immersed in an aqueous medium. In this work, we studied the sensitivity of the microdisk laser resonance spectral position to the refractive index of the surrounding material by changing the salinity of the water solution. We also successfully detected model proteins (secondary antibodies attached to the microdisk surface) via measurement of the lasing threshold power. The proteinprotein interaction on the microdisk surface manifests itself by an increase in the laser threshold power. Thus, in this work we demonstrated, for the first time, the possibility of using QD semiconductor microdisk lasers for detection of proteins in a microfluidic device.
Concentration of light into a nanospot is essential for the heat assisted magnetic recording, biomedical imaging, sensing, and nanolasing. We propose a novel all-dielectric optical field concentrator, which focuses the light, pumped through the waveguide, into a hot nanospot, which is much smaller than the wavelength. The dissipative loss, which is characteristic to a plasmonic nanoantenna, is absent in the dielectric concentrator. Therefore, the detrimental thermal effects almost vanish, which gives an opportunity to use the concentrator for the heat-assisted magnetic recording. The electric field is much enhanced in the proposed new device at the vertex of the dielectric beak, which is attached to the dielectric resonator. The resonator in turn is pumped through the special waveguide. The electric field enhancement and concentration is achieved by longitudinal polarization of the beak vertex, which is exposed to em electric field generated by the pumped resonator. The spatial scale of the hot spot, where the field concentrates, is determined by the curvature of the vertex and can be of few nanometers. We take as a design concept the cylindrical waveguide, the spherical resonator, and the elliptic beak. The rectangular, 2.5-dimensional design of the light concentrator is also considered.
A method of hybrid integration of quantum dot microdisk lasers with silicon wafer is proposed and realized. In addition to the possibility of combining microlasers with various silicon-based electronic and photonic devices, this makes it possible to significantly improve heat removal from the active region of the microlaser. The thermal resistance normalized to the mesa area reaches the level of about 0.002 (K/W)*cm2, which is significantly lower than the corresponding values of QD microlasers on GaAs substrate and monolithically grown on Si. As a result, the threshold current as well as current-induced shift of emission wavelength are reduced in continuous-wave regime.
We show that using dense arrays of InGaAs quantum well-dots enables uncooled high-frequency applications with a GHz-range bandwidth. A maximum 3-dB modulation frequency of about 6 GHz was found. The K-limited maximal frequency of 13 GHz was estimated from the modulation response analysis. The experimental values of the energy-todata reaches 1.5 pJ/bit for the smallest diameter under study (10 μm). A 23 μm in diameter microlaser exhibits open eye diagram up to 12.5 Gbit/s and is capable of error-free 10 Gbit/s data transmission at 30ºC without temperature stabilization. Our results demonstrate the potential to achieve miniature high-speed on-chip light sources for optical communication applications using lasers with a diameter of only a few micrometers.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.