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Modelowanie i optymalizacja antymonkowych laserów typu VCSEL

Piskorski Ł., Walczak J., Dems M., Beling P., Sarzała R.. P.

Przegląd Elektrotechniczny

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2015

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R. 91, nr 9

150-153

PL

W niniejszej pracy zaprezentowano wyniki komputerowej symulacji progowej pracy antymonkowego lasera o emisji powierzchniowej z pionową wnęką rezonansową z wykorzystaniem samouzgodnionego modelu lasera opisującego zjawiska elektryczne, termiczne, rekombinacyjne i optyczne. Obliczenia wykonano dla struktury dostosowanej do emisji promieniowania o długości fali 2,6 μm. Pokazane zostały zalety wprowadzenia ograniczenia dla rozpływu prądu w postaci złącza tunelowego oraz zbadano wpływ przesunięcia warstw powstałego na skutek jego wytworzenia na ograniczanie wzbudzania się modów wyższego rzędu. Zmniejszanie przesunięcia, o wartości początkowej wynoszącej 55 nm, o 35 nm spowodowało wzrost strat dla modów LP11 i LP21 odpowiednio 7 i 25 razy przy wzroście prądu progowego jedynie o 10%. Dalsza redukcja przesunięcia przyczynia się do wyraźnego wzrostu prądu progowego: 20% dla 40 nm oraz 50% dla 45 nm.

EN

In this work results of the threshold operation of antimonide-based vertical-cavity surface-emitting laser have been presented with the aid of the comprehensive fully self-consistent optical-electrical-thermal-recombination numerical model. Calculations have been carried out for the structure emitting at 2.6 μm. The advantages of incorporating the tunnel junction for current confinement have been shown and the influence of a layer shift caused by presence of the tunnel junction on the mode selectivity has been examined. It was shown that reducing the layer shift, with initial height equal to 55 nm, by the 35 nm leads to 7 and 25 times higher mode losses for LP11 and LP21 modes, respectively, and only 10% higher threshold current for the LP01 mode. Further reduction of the layer shift leads to high increment of the threshold current value: 20% for 40 nm reduction and 50% for 45 nm one.

2

Determining a Complex Solar Radio Burst Type II on 2nd November 2014 Driven by a Hydra Solar Flare As A Blast Waves

Hamidi Z. S., Ibrahim M. B., Shariff N. N. M., Monstein C.

International Letters of Chemistry, Physics and Astronomy

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2015

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Vol. 47

87--93

EN

Recent data of a complex solar radio burst type II is analyzed and reviewed. The monitoring of solar radio burst was done by using the Compact Astronomical Low cost, Low frequency Instrument for Spectroscopy and Transportable Observatory (CALLISTO) from BLEIN 7 meter dish telescope at ETH, Zurich in frequency range of 25 until 1000 MHz. During the inspection of the X-ray spectrum, we observed that the C3-category flare was caused by a filament of magnetism, which rose up and erupted between 0400 and 0600 UT. This occurred three hours before the signature of solar radio burst type II. There are some of the material in the filament fell back to the sun, causing a flash of X-rays where it hit the Sun surface. This is a Hydra Flare which occurred without sunspots. On the basis of these results, we suggest that a single shock in the leading edge of the CME could be the source of the multiple type II bursts and support the notion that the CME nose and the CME-streamer interaction are the two main mechanisms able to generate the bursts.

3

Enormous Eruption of 2.2 X-class Solar Flares on 10th June 2014

Hamidi Z. S., Shariff N. N. M.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 17, iss. 3

249--257

EN

The observational of active region emission of the Sun contain an critical answer of the time-dependence of the underlying heating mechanism. In this case, we investigate an X2.2 solar flare from a new Active Region AR2087 on the southeast limb of the Sun. The solar flare peaked in the X-rays is around 11:42 UT. It was found that the snapshot of this event from the Solar Dynamics Observatory (SDO) channel with the GOES X-ray plot overlayed. The flare is very bright causes by a diffraction pattern. We explore a parameter space of heating and coronal loop properties. Based on the wavelength, it shows plasma around 6 million Kelvin. At the same time, data from the NOAA issued an R3 level radio blackout, which is centered on Earth where the Sun is currently overhead at the North Africa region. This temporary blackout is caused by the heating of the upper atmosphere from the flare. The blackout level is now at an R1 and this will soon pass. Other than the temporary radio blackout for high frequencies centered over Africa this event will not have a direct impact on us. Until now, we await more data concerning a possible Coronal Mass Ejections (CMEs) but anything would more than likely not head directly towards Earth. An active region AR2087 just let out an X1.5 flare peaking at 12:52 UT. This shows plasmas with temperatures up to about 10 Million Kelvin. This event is considered one of the massive eruption of the Sun this year.

4

An Analysis of Solar Burst Type II, III, and IV and Determination of a Drift Rate of a Single Type III Solar Burst

Hamidi Z. S., Ibrahim M. B., Shariff N. N. M., Monstein C.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 19, iss. 2

160--170

EN

The main feature of solar radio type II, III and IV burst is outlined. In this event there are three combinations of bursts that related to the solar flare phenomenon on 6th July 2012. This event is one of good example to observe how far the influence of type II burst could impact the formation of type IV burst and III solar bursts. At first stage, it was observed that a sub-type of H burst form within 2 minutes before type IV solar burst form. The type IV burst is due to the eruption of active region AR 1515 with a fine structure (FS). We used a Blein CALLISTO data in this case. Further analysis also showed that the total energy of the burst are in the range of 4.875 × 10-25 J to 8.48 × 10-25 J and plasma frequency is equal to 1.24 × 104 Hz. Therefore, we could say that in this case, before the solar burst type III occurred, the ejection of CMEs already ejected.

5

A Case Study of Explosion A Single Solar Burst Type III and IV Due to Active Region AR1890

Hamidi Z. S., Ibrahim M. B., Shariff N. N. M., Monstein C.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 19, iss. 2

171--180

EN

Using data from a BLEIN Callisto site, we aim to provide a comprehensive description of the synopsis formation and dynamics of a a single solar burst type III and IV event due to active region AR1890. This eruption has started since 14:15 UT with a formation of type III solar burst. To investigate the importance of the role of type III solar burst can potentially form a type IV solar burst, the literature review of both bursts is outlined in detailed. The orientation and position of AR1890 make the explosion of a class C-solar flare is not directly to the Earth. Nevertheless, it is clear that the interactions of others sunspots such as AR1893,AR1895,AR1896, AR1897 and AR1898 should be studied in detail to understand what makes the type III burst formed before the type IV solar burst.

6

Application of active region model for detection of liver cancer

Tracz P., Szczepaniak P. S., Tomczyk A.

Journal of Medical Informatics & Technologies

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2011

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Vol. 17

263--268

EN

Active region models are methods for automatic image segmentation. The models are able to detect shapes of irregular borders. In the present paper, the method is examined using medical images of liver changed locally by cancer cells.

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Optical characterisation of strained-layer In/sub x/Ga/sub 1-x/As/GaAs MQW LED grown by MOVPE.

Sęk G., Ciorga M., Bryja L., Misiewicz J., Radziewicz D., Ściana B., Tłaczała M.

Optica Applicata

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2000

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Vol. 30, nr 1

183-188

EN

We present the use of photoreflectance (PR) spectroscopy combined with the standard photoluminescence (PL) and electroluminescence (EL) for the room temperature optical investigation of strained-layer multiple quantum well (MQW) In/sub x/Ga/sub 1-x/As/GaAs light emitting diode (LED) for 1040 nm. In the PR spectra, except the fundamental transition observed also in the emission spectra, two extra features related to the active region of the device have been seen. The presence of these two excited state transitions allowed the band structure to be analysed and the correctness of the device performance to be checked. We repeated the measurements after the top p-doped GaAs cladding layer had been etched off and discussed the changes of the built-in electric field.