International Journal of Online Engineering最新文献

{"title":"Speed Performance Degradation of Electrooptic Modulator Devices by Neutrons Irradiations at High temperature Effects","authors":"Ahmed Nabih, Z. Rashed","doi":"10.5923/J.IJOE.20110101.01","DOIUrl":"https://doi.org/10.5923/J.IJOE.20110101.01","url":null,"abstract":"In the present paper, we have deeply investigated the transmission efficiency degradation of electrooptic modulator devices in thermal irradiated hard environments over wide range of the operating parameters. It is well known that the radiation-induced electrooptic modulator defects can modify the initial doping concentrations, creating generation-recombination centres and introducing trapping of carriers. Additionally, rate of the lattice defects is thermally activated and reduces for increasing irradiation temperature as a result of annealing of the damage. Both the ambient temperature and the irradiation dose possess sever effects on the electro-optical characteristics and consequently the performance characteristics of electroptic modulator devices. As well as we have deeply developed the modelling basics of electrooptic modulator devices, which may be used to analyzed the modulator quantum efficiency, dark current, modulating voltage, modulating frequency, 3-dB bandwidth, transmitted signal bandwidth, modulator quality factor, modulator sensitivity, modulator sensitivity bandwidth product, switching voltage, modulator device performance index, operating switching time and speed response of these irradiated electrooptic modulator devices after different irradiation fluences.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"19 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88327383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A high-performance Test-Bed Dedicated for Responsivity Measurements of Infrared Photodetectors in a Wide Band of Low Temperatures","authors":"L. A. Faria, L. Nohra, N. Gomes, F. Alves","doi":"10.5923/J.IJOE.20120203.01","DOIUrl":"https://doi.org/10.5923/J.IJOE.20120203.01","url":null,"abstract":"Nowadays, the detection in the infrared band (IR) has shown great importance in several areas such as skin illnesses detection, remote sensor and in different military devices. The responsible for such detection is, basically, photodetector arrays (FPA) sensitive to infrared radiation. This paper presents a modular and adaptative test-bed, based upon an arrangement of 24 electro and optical components divided in four major functional blocks, providing methodological procedures that allows an accurate design verification of infra-red photodetectors. The target metric that the system is con- ceived to provide is Responsivity. In essence, the developed system differs from the previous ones by its adaptability and its hardware modularity conception that allows an easy reconfiguration to test different kinds of photodetectors. Here we compare a theoretical calculation of responsivity with actual experimental measurements, allowing low temperature meas- urements between 16K and 100K, in wavelength from 0.7μm up to 12μm (0.8μm to 1.0μm in this work) and the possibility to set detectors with up to 10 I/O electric terminals. The operational validation of this test-bed is achieved with a studied Quantum Well Infrared Photodetectors (QWIP), exhibiting high compliance with the expected theoretical results.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"9 1","pages":"12-17"},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87360494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optical and Other Measurement Techniques of Carrier Lifetime in Semiconductors","authors":"Y. Arafat, F. M. Mohammedy, M. Hassan","doi":"10.5923/J.IJOE.20120202.02","DOIUrl":"https://doi.org/10.5923/J.IJOE.20120202.02","url":null,"abstract":"In this paper, various methods for characterization of semiconductor charge carrier lifetime are reviewed and an optical technique is described in detail. This technique is contactless, all-optical and based upon measurements of free carrier absorption transients by an infrared probe beam following electron-hole pair excitation by a pulsed laser beam. Main features are a direct probing of the excess carrier density coupled with a homogeneous carrier distribution within the sample, enabling precision studies of different recombination mechanisms. The method is capable of measuring the lifetime over a broad range of injections (10 13 -10 18 cm -3 ) probing the minority carrier lifetime, the high injection lifetime and Auger recombination, as well as the transition between these ranges. Performance and limitations of the technique, such as lateral resolution, are addressed while application of the technique for lifetime mapping and effects of surface recombination are also outlined. Results from detailed studies of the injection dependence yield good agreement with the Shockley-Read-Hall theory, whereas the coefficient for Auger recombination shows an apparent shift to a higher value, with respect to the traditionally accepted value, at carrier densities below 2×10 17 cm -3 . Data also indicate an increased value of the coefficient for bimolecular recombination from the generally accepted value. Measurement on an electron irradiated wafer and wafers of exceptionally high carrier lifetimes are also discussed within the framework of different recombination mechanisms.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"19 1","pages":"5-11"},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83521763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear Material Based All-Optical Parallel Subtraction Scheme: an Implementation","authors":"S. Sahu, R. Pal, Shantanu Dhar","doi":"10.5923/J.IJOE.20110101.02","DOIUrl":"https://doi.org/10.5923/J.IJOE.20110101.02","url":null,"abstract":"Non-linear material based all-optical switching mechanism is utilized here to implement the all-optical paral- lel subtraction scheme. Optical tree architectures here convert analog optical signal to the corresponding digital one. A two bit all-optical binary parallel subtractor has been proposed and which may be elevated to a higher bit parallel subtractor in course using all-optical half-subtractor and a full-subtractor. These are constructed by a composite slab of linear medium (LM) and non-linear medium (NLM) and it is the building block of our proposed subtructor circuit. These circuits are all-optical and fully parallel in nature. It can also gear up to the highest ability of optical performance in high-speed all-optical computing system.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"199 1","pages":"7-11"},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76162723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physical Properties of Zn x Cd 1-x S Nanocrytalline Layers Synthesized by Solution Growth Method","authors":"K. Nagamani, V. Reddy, Y. Lingappa, K. Reddy, R. Miles","doi":"10.5923/J.IJOE.20120202.01","DOIUrl":"https://doi.org/10.5923/J.IJOE.20120202.01","url":null,"abstract":"In recent years, zinc cadmium sulphide (ZnxCd1-xS) alloy compounds have paid much attention in the fields of opto-electronics, particularly in photovoltaic devices because of its tunable energy gap and the lattice parameters. The energy band gap of ZnxCd1-xS is controlled by the change of Zn-composition in order to suit the material properties with that of absorber material in solar cells. In this paper, we report on the effect of Zn-composition on physical properties of ZnxCd1-xS thin films deposited on corning glass substrates by solution growth method. The layers were prepared for different 'x' values that vary in the range, 0 - 1.0 at. %. The as-grown layers were characterized using EDAX, XRD, SEM, and UV-Vis-NIR spectrophotometers. All the layers showed a strong (002) plane as the preferred orientation that exhibited the hexagonal crystal structure. The composition of the layers agrees approximately with that of the elements in the solution. The films showed an average optical transmittance of 72 % at a zinc composition of 0.75 with a band gap of 3.88 eV.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"24 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2012-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80807058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectral Efficient Coding Schemes in Optical Communications","authors":"T. Lotz, W. Sauer-Greff, R. Urbansky","doi":"10.5923/J.IJOE.20120204.01","DOIUrl":"https://doi.org/10.5923/J.IJOE.20120204.01","url":null,"abstract":"Achieving high spectral efficiency in optical transmissions has recently attracted much attention, aiming to satisfy the ever increasing demand for high data rates in optical fiber communications. Therefore, strong Forward Error Correction (FEC) coding in combination with multilevel modulation schemes is mandatory to approach the channel capacity of the transmission link. In this paper we give design rules on the joint optimization of coding and signal constellations under practical considerations. We give trade-offs between spectral efficiency and hardware complexity, by comparing coding schemes using capacity achieving constellations with bit-interleaved coded modulation and iterative decoding (BICM-ID) against applying conventional square quadrature amplitude modulation (QAM) constellations but employing powerful low complexity low-density parity-check (LDPC) codes. Both schemes are suitable for optical single carrier (SC) and optical orthogonal frequency-division multiplexing (OFDM) transmission systems, where we consider the latter one in this paper, due to well-studied equalization techniques in wireless communications. We numerically study the performance of different coded modulation formats in optical OFDM transmission, showing that for a fiber optical transmission link of 960 km reach the net spectral efficiency can be increased by ≈0.4 bit/s/Hz to 8.61 bit/s/Hz at a post FEC BER of <10-15 by using coded optimized constellations instead of coded 64-QAM.In this paper we propose a high spectral efficient coded modulation scheme for implementation in future optical communication systems operating at data rates beyond 400 Gb/s. In detail, we adapt the “Turbo Principle” to BICM-ID[8] and combine it with a high-rate outer algebraic code to obtain a post-FEC BER <10-15, which is a typical demand in optical transponders. Furthermore we give simple design principles for the design of BICM-ID based on the extrinsic information transfer (EXIT) chart analysis[9]. The optical channel is considered to be weakly-nonlinear. Therefore the proposed techniques are also applicable for single-carrier transmission; however we consider OFDM since it appears to be more appropriate for the high order modulation formats and efficient equalization algorithms that are well established in wireless communications.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"33 1","pages":"18-25"},"PeriodicalIF":0.0,"publicationDate":"2012-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82886323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-Contact Vibration Sensor Using Bifurcated Bundle Fiber for Real Time Monitoring of Diesel Engine","authors":"P. Kishore, D. Dinakar, M. S. Shankar, K. Srimannarayana, P. V. Rao, D. Sengupta","doi":"10.5923/J.IJOE.20120201.02","DOIUrl":"https://doi.org/10.5923/J.IJOE.20120201.02","url":null,"abstract":"A non-contact vibration sensor is demonstrated using bifurcated bundle fiber based on the principle of extrinsic reflective intensity modulation for monitoring the health condition of the diesel engine. An IR-source is used along with glass fibers to avoid the effect of stray light in sensing. The encapsulation of the sensor enables easy alignment, flexible handling and usage in harsh environments. The sensor is capable of measuring the frequencies up to 650Hz with vibration amplitude resolution of 10µm, enough to monitor the vibrations generated in heavy machines like diesel engine.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"484 1","pages":"4-9"},"PeriodicalIF":0.0,"publicationDate":"2012-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86767219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"50 GHz Spaced 25 × 40 Gbit/s WDM Transmission Over 560 km Using SMF-Based Large Effective Area Fiber (LEAF)","authors":"M. Nahas","doi":"10.5923/J.IJOE.20120201.04","DOIUrl":"https://doi.org/10.5923/J.IJOE.20120201.04","url":null,"abstract":"In this paper, we present 50 GHz spaced 25 × 40 Gbit/s WDM transmission over 560 km using SMF-based Large Effective Area Fiber (LEAF) in a recirculating loop. The paper uses band-limited RZ signals carrying 2 31 -1 PRBS data, and shows that transmission distance of 560 km can be achieved with BER ≤ 10 -9 using 1 mW peak power and 4 ps pulse-width for each data signal. To attain this, optical filters with sharp transmission characteristics are used in both transmitter and receiver. The results demonstrated in this paper are based on simulation, and the author believes that the propagation distance reached in the paper is the longest distance achieved for such system","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"33 6 1","pages":"17-20"},"PeriodicalIF":0.0,"publicationDate":"2012-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82774132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multivariate Statistical Analysis in Planning Experiments for a New Strontium Bromide Vapour Laser","authors":"I. Iliev, S. Gocheva-Ilieva, K. Temelkov, N. Vuchkov, N. Sabotinov","doi":"10.5923/J.IJOE.20120201.03","DOIUrl":"https://doi.org/10.5923/J.IJOE.20120201.03","url":null,"abstract":"The subject of investigation is a SrBr2 laser generating at a wavelength λ = 6.45 µm. This type of laser gen- eration is finding ever wider application in medicine when working with soft and bone tissue providing rapid subsequent recovery. Of all laser sources generating at this wavelength, the new SrBr2 laser is gaining ever more ground due to its ad- vantages and is therefore of commercial interest. With the goal of developing new, higher-powered SrBr2 lasers, in this paper, the so-called phenomenological modeling has been used for the first time for this type of laser. An estimation of the degree of influence of 7 independent input laser quantities on laser output power has been performed using factor and regression analysis. A methodology has been developed with the help of which a series of new SrBr2 lasers with higher output power than existing ones has been predicted. Problems related to the planning of the experiment have been partially solved - car- rying out of filtering and extremal experiment.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"68 1","pages":"10-16"},"PeriodicalIF":0.0,"publicationDate":"2012-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79505419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optomechanical Properties of 10% PVA (Polyvinylalcohol) in Presence of CoCl 2 and 44% Ethanol Water Compositions","authors":"M. Hamada, E. Gomaa, N. A. El-Shishtawi","doi":"10.5923/j.ijoe.20120201.01","DOIUrl":"https://doi.org/10.5923/j.ijoe.20120201.01","url":null,"abstract":"The optical and mechanical properties of 10% by weight for PVA (Polyvinyl alcohol) in presence of different CoCl2 concentrations in absence and presence of 44 % by weight ethanol - water solvents were estimated at 298.15 K. The evaluated optical parameters like molar refraction (RM),specific refractivity(e) and molecular polarizability (α) were com- pared and discussed with that of mechanical tension parameters like elastic modulus and Shear modulus.","PeriodicalId":14375,"journal":{"name":"International Journal of Online Engineering","volume":"71 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2012-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82464382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}