Wyniki wyszukiwania - BazTech

1

Optimization of optical characteristics of In0.29Ga0.71As0.99N0.01/GaAs straddled nano-heterostructure

Sandhya K., Bhardwaj G., Dolia R., Lal P., Kumar S., Dalela S., Rahman F., Alvi P. A.

Opto-Electronics Review

|

2018

|

Vol. 26, No. 3

210--216

EN

Designing of a nanoscale Quantum Well (QW) heterostructure with a well thickness of ~60 Å is critical for many applications and remains a challenge. This paper has a detailed study directed towards designing of In0.29Ga0.71As0.99N0.01/GaAs straddled nanoscale-heterostructure having a single QW of thickness ~60 Å and optimization of optical and lasing characteristics such as optical and mode gain, differential gain, gain compression, anti-guiding factor, transparency wavelength, relaxation oscillation frequency (ROF), optical power and their mutual variation behavior. The outcomes of the simulation study imply that for the carrier concentration of ~2 × 10¹⁸cm⁻³ the optical gain of the nano-heterostructure is of 2100 cm⁻¹ at the wavelength is of 1.30 μm. Though the obtained gain is almost half of the gain of InGaAlAs/InP heterostructure, but from the wavelength point of view the InGaAsN/GaAs nano-heterostructure is also more desirable because the 1.30 μm wavelength is attractive due to negligible dispersion in the silica based optical fiber. Hence, the InGaAsN/GaAs nano-heterostructure can be very valuable in optical fiber based communication systems.

2

Struktura pasmowa i wzmocnienie optyczne studni kwantowych GeSn/Ge

Mączko H., Gładysiewicz M., Kudrawiec R.

Przegląd Elektrotechniczny

|

2017

|

R. 93, nr 8

13--16

PL

W niniejszej pracy zaprezentowano wyniki obliczeń struktury pasmowej i widm wzmocnienia optycznego dla studni kwantowych Ge/Ge1-xSnx/Ge. Dokonano optymalizacji składu x i grubości studni d do zastosowań w laserach półprzewodnikowych, w wyniku której uzyskano propozycje korzystnych wartości parametrów studni kwantowej: 0,15 < x < 0,17, d ~ 12 mm.

EN

In this work band structure and optical gain was calculated for Ge/Ge1-xSnx/Ge quantum wells. Ottomanization of x composition and the thickness of the well d were made for use in semiconductor lasers. As a result of optimization achieved the optimum parameter values of quantum wells: 0.15 < x < 0.17, d ~ 12 nm.

3

Modelowanie transportu elektronów w kwantowych laserach kaskadowych

Kolek A.

Elektronika : konstrukcje, technologie, zastosowania

|

2014

|

Vol. 55, nr 11

18-26

PL

W artykule omówiono metody modelowania obszaru aktywnego struktury kwantowego lasera kaskadowego. Na przykładzie struktury lasera, emitującego w zakresie średniej podczerwieni, wskazano analogie i różnice między obrazem transportu elektronowego wynikające z analizy z użyciem m.in. najprostszego modelu równań kinetycznych, metody macierzy gęstości oraz najbardziej zaawansowanym modelem bazującym na formalizmie nierównowagowych funkcji Greena. Uzupełnieniem ww. metod jest metoda Monte Carlo, w której możliwe jest m.in. uwzględnienie rozproszeń elektron-elektron oraz rozproszeń międzydolinowych.

EN

In the paper, the modeling methods of active region of quantum cascade laser (QCL) structure are reviewed. For QCL structure, emitting in the mid-infrared range, the similarities and the differences between electron transport image resulting from (i) the simplest rate equations model, (ii) the density matrix method, and (iii) the most advanced model based on nonequilibrium Green’s formalism are discussed. The Monte Carlo method, which benefits from including electron-electron, electron-photon, and intervalleys scatterings, is also considered.

4

Nanostructure model and optical properties of InAs/GaAs quantum dot in vertical cavity surface emitting lasers

Chen J., Fan W. J., Ding Y., Xu Q., Zhang X. W., Xu D. W., Yoon S. F., Zhang D. H.

Opto-Electronics Review

|

2011

|

Vol. 19, No. 4

449-453

EN

We apply 8.band k.p model to study InAs/GaAs quantum dots (QDs). The strain was calculated using the valence force field (VFF) model which includes the four nearest.neighbour interactions. For the optical properties, we take into account both homogeneous and non.homogeneous broadening for the optical spectrum. Our simulation result is in good agreement with the experimental micro.photoluminescence (µm-PL) result which is from InAs/GaAs QD vertical cavity surface emitting lasers (VCSELs) structure wafer at room temperature. Accordingly, our simulation model is used to predict the QD emission from this QD.VCSELs structure wafer at different temperature ranging from 200–400 K. The simulation results show a decrease of 41 meV of QDground state (GS) transition energy from 250–350 K. The changes ofQDGS transition energy with different temperature indicate the possible detuning range for 1.3.µm wave band QD-VCSELs applications without temperature control. Furthermore, QD differential gain at 300 K is computed based on this model, which will be useful for predicting the intrinsic modulation characteristics of QD-VCSELs.

5

Optical gain in one-dimensional photonic band gap structures with n-i-p-i crystal layers

Nefedov I.S., Gusyatnikov V.N., Marciniak M., Kononenko V.K., Ushakov D.V.

Journal of Telecommunications and Information Technology

|

2002

|

nr 1

60-64

EN

The gain enhancement in a layered periodic photonic band gap structure containing active medium based on GaAs n-i-p-i superlattices separated by A1GaAs layers is analyzed. The dependences of extinction coefficient and refractive index on excitation level and wavelength are presented. Transmission characteristics of a probe light versus excitation level are calculated. It is shown that the threshold of generation can be essentially reduced if the wavelength of probe light falls to the band gap edge.

6

Impact of mismatch-related phenomena on a room-temperature operation of nitride VCSELs.

Maćkowiak W., Nakwaski W.

Optica Applicata

|

2000

|

Vol. 30, nr 1

125-140

EN

The influence of mismatch-related phenomena (mostly strain fields and structure defects) on a room-temperature (RT) operation of possible nitride VCSELs is examined using a simple but still detailed analytical model. Intentionally introduced stress fields within nitride VCSEL quantum-well (QW) active regions (band-gap engineering) are found to have a much weaker effect on their optical gain than in the case of conventional arsenide and phosphide VCSELs. Dislocation densities (including misfit dislocations), on the other hand, have a considerable harmful impact on VCSELs thresholds, mostly because of increasing scattering losses and decreasing internal quantum efficiency. Single-quantum-well nitride VCSELs are found to be very sensitive to the above impact. A reasonable increase in a number of QWs in multiple-quantum-well VCSELs tremendously improves their performance. In the case of relatively high dislocation densities, bulk double-heterostructure VCSELs may turn out to be the best nitride designs although they may also exhibit too high thresholds to lase at RT.

7

Electromagnetic limit of the optical gain for long-wave IR diffractive optics.

Sikorski Z., Piotrowski J., Grudzień M.

Optica Applicata

|

2000

|

Vol. 30, nr 1

151-160

EN

Focal plane collection optics consisting of arrays of microlenses may be used to reduce the physical size of an infrared detector without reduction of its apparent optical size and quantum efficiency. This results in reduction of the thermal generation rate in the detector, allowing improvement of performance of infrared devices operating at elevated temperatures. We report on calculations of the optical gain achievable with the use of diffractive microlenses for long-wave (8-22 mu m) infrared (LWLR) detectors. Fast diffractive lenses are required for this application, and binary optics is the most popular technology of their fabrication. A large fraction of the binary lens surface relief is built of staircase annular structures whose width is of wavelength-scale. Therefore, the electromagnetic theory of gratings has been applied in the paper to calculate the diffraction efficiency of the Fresnel zones for the multi-phase-level lenses. It is shown that electromagnetic effects limit the speed of the LWIR diffractive lenses.