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Alcohol Sensing Over O＋E＋S＋C＋L＋U Transmission Band Based on Porous Cored Octagonal Photonic Crystal Fiber

Photonic Sensors 2017年第2期7卷 123-130页

作者： bikash kumar paul Md. Shadidul ISLAM Kawsar AHMED Sayed ASADUZZAMAN Department of Information and Communication Technology Mawlana Bhashani Science and Technology University Santosh Tangail-1902 Bangladesh Group of Bio-Photomatriz Tangail-1902 Bangladesh Department of Software Engineering Daffodil International University Sukrabad Dhaka Bangladesh

A micro structure porous cored octagonal photonic crystal fiber （P-OPCF） has been proposed to sense aqueous analysts （alcohol series） over a wavelength range of 0.80 μm to 2.0 μm. By implementing a full vectorial finite element method （FEM）, the numerical simulation on the proposed O-PCF has been analyzed. Numerical investigation shows that high sensitivity can be gained by changing the structural parameters. The obtained result shows the sensitivities of 66.78%, 67.66%, 68.34%, 68.72%, and 69.09%, and the confinement losses of 2.42×10^-10 dB/m, 3.28x×10^-11 dB/m, 1.21 ×10^-6 dB/m, 4.79×10^-10 dB/m, and 4.99×10^-9 dB/m at the 1.33 ktm wavelength for methanol, ethanol, propanol, butanol, and pentanol, respectively can satisfy the condition of much legibility to install an optical system. The effects of the varying core and cladding diameters, pitch distance, operating wavelength, and effective refractive index are also reported here. It reflects that a significant sensitivity and low confinement loss can be achieved by the proposed P-OPCE The proposed P-OPCF also covers the wavelength band （O＋E＋S＋C＋L＋U）. The investigation also exhibits that the sensitivity increases when the wavelength increases like SO-band〈SE-band 〈SS-band 〈 SC-band 〈SL-band 〈SU-band. This research observation has much pellucidity which has remarkable impact on the field of optical fiber sensor.

关键词： Porous cored OPCF alcohol sensor sensitivity confinement loss transmission band

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Single polarization photonic crystal fiber filter based on surface plasmon resonance

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Frontiers of Optoelectronics 2019年第2期12卷 157-164页

作者： Md. Nazmul HOSSEN Md. FERDOUS Kawsar AHMED Md. Abdul KHALEK Sujan CHAKMA bikash kumar paul Department of Information and Communication Technology(ICT) Mawlana Bhashani Science and Technology University(MBSTU)SantoshTangail 1902Bangladesh Group of Biophotomatix SantoshTangail 1902Bagladesh Department of Software Enineering(SWE) Daffodil International UniversityShukrabadDhaka 1207Bangladesh

In this paper,we propose a photonic crystal fiber(PCF)polarization filter based on surface plasmon resonance(SPR)characteristics.Gold nanowire is used as the active plasmonic material.Light into silica core becomes coupled to gold nanowire stimulating SPR. It soplits light into two orthogonal(x-polarization and y-polarization)polarization in the second order of surface plasmon polarization.Numerical investigations of the proposed PCF filter is finite element method(FEM).By position,the performance of the propsed PCF filter is inspected rigorously.Filtering of any polarization can be obtained by properly placing the metal wires.The maximum cnfinement loss of x-polarization is 692.25dB/cm and y-polarization is 1.13dB/cm offers at resonance position 1.42μm.Such a confinement loss difference between two orthogonal polarizations makes PCF a talented candidate to filter devicees.Consequently,the recommended PCF structure is useful for polarization device.

关键词： photonic crystal fiber (PCF) surface plasmon resonance (SPR) perfectly match layer polarization filter

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Design and Optimization of Photonic Crystal Fiber Based Sensor for Gas Condensate and Air Pollution Monitoring

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Photonic Sensors 2017年第3期7卷 234-245页

作者： Md. Ibadul ISLAM Kawsar AHMED Shuvo SEN Sawrab CHOWDHURY bikash kumar paul Md. Shadidul ISLAM Mohammad Badrul Alam MIAH Sayed ASADUZZAMAN Department of Information and Communication Technology (ICT) Mawlana Bhashani Science and Technology University Santosh Tangail 1902 Bangladesh Group of Bio-photomatix Tangail 1902 Bangladesh Department of Software Engineering (SWE) Daffodil International University Sukrabad Dhaka 1207 Bangladesh

In this paper, a hexagonal shape photonic crystal fiber （H-PCF） has been proposed as a gas sensor of which both micro-structured core and cladding are organized by circular air cavities. The reported H-PCF has a single layer circular core which is surrounded by a five-layer hexagonal cladding. The overall pretending process of the H-PCF is completed by using a full vectorial finite element method （FEM） with perfectly matched layer （PML） boundary condition. All geometrical parameters like diameters and pitches of both core and cladding regions have fluctuated with an optimized structure. After completing the numerical analysis, it is clearly visualized that the proposed H-PCF exhibits high sensitivity with low confinement loss. The investigated results reveal the relative sensitivity of 56.65% and confinement loss of 2.31×10^-5 dB/m at the 1.33%tm wavelength. Moreover, effective area, nonlinearity, and V-parameter of the suggested PCF are also briefly described.

关键词： Relative sensitivity confinement loss gas sensor effective area nonlinearity and photonic crystal fiber

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Variations of the harmonic components of the X-ray pulse profile of PSR B1509–58

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Research in Astronomy and Astrophysics 2015年第1期15卷 28-36页

作者： Pragati Pradhan Biswajit paul Harsha Raichur bikash Chandra paul St Joseph’s College Singamari Darjeeling 734104 West Bengal India North Bengal University Raja Rammohanpur District Darjeeling 734013 West Bengal India Raman Research Institute Sadashivnagar Bangalore 560080 India

We used the Fourier decomposition technique to investigate the stability of the X-ray pulse profile of a young pulsar PSR B1509–58 by studying the relative amplitudes and phase differences of its harmonic components with respect to the fundamental using data from the Rossi X-Ray Timing Explorer. Like most young rotation powered pulsars, PSR B1509–58 has a high spin down rate. It also has less timing noise, allowing accurate measurement of higher order frequency derivatives which in turn helps in the study of the physics of pulsar spin down. Detailed investigation of pulse profiles over the years will help us establish any possible connection between the timing characteristics and the high energy emission characteristics for this pulsar.Furthermore, the study of pulse profiles of short period X-ray pulsars can also be useful when used as a means of interplanetary navigation. The X-ray pulse profile of this source has been analyzed for 15 yr（1996–2011）. The long term average amplitudes of the first, second and third harmonics（and their standard deviation for individual measurements） compared to the fundamental are 36.9%（1.7%）, 13.4%（1.9%） and 9.4%（1.8%） respectively. Similarly, the phases of the three harmonics（and standard deviations） with respect to the fundamental are 0.36（0.06）, 1.5（0.2） and 2.5（0.3） radian respectively. We do not find any significant variation of the harmonic components of the pulse profile in comparison to the fundamental.

关键词： pulsars： individual：（PSR B1509–58） stars： neutron X-rays

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A report on TypeⅡX-ray bursts from SMC X-1

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Research in Astronomy and Astrophysics 2018年第12期18卷 43-52页

作者： Binay Rai Pragati Pradhan bikash Chandra paul Dept.of Physics North Bengal UniversityDarjeelingWest Bengal734013India Department of Astronomy and Astrophysics Pennsylvania State UniversityPennsylvania16802USA St.Joseph's College Darjeeling-734104West BengalIndia

We study RXTE PCA data for the high mass X-ray binary source SMC X-1 between 2003–10 and 2003–12 when the source was in its high states.The source is found to be frequently bursting which can be seen as flares in lightcurves that occur at a rate of one every 800 s, with an average of 4–5 Type Ⅱ X-ray bursts per hour.We note that typically a burst was short, lasting for a few tens of seconds in addition to a few long bursts spanning more than a hundred seconds that were also observed.The flares apparently occupied 2.5% of the total observing time of 225.5 ks.We note a total of 272 flares with mean FWHM of the flare ～21 s.The rms variability and aperiodic variability are independent of flares.As observed, the pulse profiles of the lightcurves do not change their shape, implying that there is no change in the geometry of an accretion disk due to a burst.The hardness ratio and rms variability of lightcurves exhibit no correlation with the flares.The flare fraction shows a positive correlation with the peak-to-peak ratio of the primary and secondary peaks of the pulse profile.The observed hardening or softening of the spectrum cannot be correlated with the flaring rate but may be due to the interstellar absorption of X-rays as evident from the change in hydrogen column density(n_H).It is found that the luminosity of the source increases with the flaring rate.Considering that the viscous timescale is equal to the mean recurrence time of flares, we fixed the viscosity parameter α ～ 0.16.

关键词： accretion accretion discs pulsar:individual(SMC X-1) stars:neutron X-rays:binaries X-ray:burst

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