Characterization of Laser Ablated SrAl2O4:Eu2+, Dy3+ Thin Films Deposited on the Optimum Substrate Temperature Range
Issue:
Volume 6, Issue 1, March 2018
Pages:
1-7
Received:
18 November 2017
Accepted:
21 December 2017
Published:
16 January 2018
Abstract: The morphological, structural and photoluminescence (PL) of laser ablated SrAl2O4:Eu2+, Dy3+ thin films deposited on optimum substrate temperature range of 200-500°C are reported. The 200-500°C substrate temperature was considered, since on that range, low cost highly emitting SrAl2O4:Eu2+, Dy3+ thin films are always produced. The surface morphology analysis of the films was done by using the scanning electron microscopy (SEM) and atomic force microscopy (AFM). The energy dispersive X-ray spectrometer (EDS) was employed for elemental composition analysis. The structural analysis was done by the X-ray diffraction (XRD) technique. The photoluminescence (PL) data collection was done by using Cary Eclipse fluorescence spectrophotometry. The films were excited by the UV light from the xenon lamp. The highest green emission intensity with a peak at 517 nm and highest initial afterglow intensity were recorded by the sample that was deposited at 350°C. The green peak at 517 nm is attributed to 4f65d1 → 4f7 Eu2+ transitions. AFM images with well defined grains were observed on the films deposited at temperatures higher than 200°C. The EDS elemental composition analysis showed that the films consist of all the main elements of SrAl2O4:Eu2+, Dy3+, i.e., Al, Sr, O. The changes in the film photoluminescence and morphology with the substrate temperature are discussed.
Abstract: The morphological, structural and photoluminescence (PL) of laser ablated SrAl2O4:Eu2+, Dy3+ thin films deposited on optimum substrate temperature range of 200-500°C are reported. The 200-500°C substrate temperature was considered, since on that range, low cost highly emitting SrAl2O4:Eu2+, Dy3+ thin films are always produced. The surface morpholog...
Show More
The Effect of He-Ne and Diode Lasers on the Electrical Characteristics of Silicon Diode
Yousif Hassan Alsheikh Abd Alraheim,
Zainab Abdulla Mohamed Taha,
Zainab Mohamed Taha
Issue:
Volume 6, Issue 1, March 2018
Pages:
8-13
Received:
30 October 2017
Accepted:
11 November 2017
Published:
18 January 2018
Abstract: The effect of He-Ne (632.8 nm) and diode (650 nm) lasers on the electrical characteristics of silicon diode have been studied. The electrical characteristics of the diode were recorded before laser irradiations, then the diode is subjected to He-Ne laser for 5 and 10 minutes and then the diode electrical characteristics were recorded for each time of exposure and the same was done in the case of irradiation with diode laser. The electrical characteristics of the diode before and after laser irradiations were compared and thermal effect was noticed when compared the effect of lasers irradiation and the well known temperature effect on the electrical characteristics of the diode. It was found that the effect of the He-Ne (632.8 nm) and diode laser (650 nm) on the electrical characteristics of silicon diode at exposure time of 5 minutes were comparable but for 10 minutes of exposure the effect of He-Ne laser irradiation on the characteristics was different from that of diode laser and this is due to the fact that the two lasers has different properties.
Abstract: The effect of He-Ne (632.8 nm) and diode (650 nm) lasers on the electrical characteristics of silicon diode have been studied. The electrical characteristics of the diode were recorded before laser irradiations, then the diode is subjected to He-Ne laser for 5 and 10 minutes and then the diode electrical characteristics were recorded for each time ...
Show More
BER Performance of PDM 4-QAM Optical Transmission System Considering the Effects of PMD and GVD Using Exact Probability Density Function
Kazi Abu Taher,
Satya Prasad Majumder
Issue:
Volume 6, Issue 1, March 2018
Pages:
14-19
Received:
20 January 2018
Accepted:
11 February 2018
Published:
14 March 2018
Abstract: A noble theoretical approach is presented to evaluate the bit error rate (BER) performance of an optical polarization division multiplexed (PDM) 4-multilevel quadrature amplitude modulation (4-QAM) transmission system under the combined influence of polarization mode dispersion (PMD) and group velocity dispersion (GVD) in a single mode fiber (SMF). The analysis is carried out considering a coherent homodyne receiver. The exact probability density function (pdf) fluctuation due to PMD and GVD is evaluated from its moments using a Monte-Carlo simulation technique. Average BER is evaluated by averaging the conditional BER over the pdf of the random phase fluctuation. BER performance results are evaluated for different system parameters. It is found that PDM 4-QAM coherent homodyne system doubles the data rate but suffers more power penalty than the 4-QAM system. Results show that for a BER of 10-9 at DGD of 0.5T and GVD value of 1700 ps/nm the PDM 4-QAM system needs 2.21 dB more power than 4-QAM systems giving the leverage of doubling the data rate.
Abstract: A noble theoretical approach is presented to evaluate the bit error rate (BER) performance of an optical polarization division multiplexed (PDM) 4-multilevel quadrature amplitude modulation (4-QAM) transmission system under the combined influence of polarization mode dispersion (PMD) and group velocity dispersion (GVD) in a single mode fiber (SMF)....
Show More
