JEOS:RP - Journal of the European Optical Society Rapid publications
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Correction for mapping errors in non-null test of aspheric surface
Full text linkThe non-null testing methods have the potential to allow measurement of aspheric surfaces with large departures from a reference sphere. In a non-null configuration, the ray will return along a different path and interfere with a different reference ray. This difference in ‘’mapping†between the test and reference rays creates an additional optical path difference (OPD) contribution, which causes test part errors to be mapped to the wrong location. To correct the mapping errors in non-null test of aspheric surface, correction method are proposed by ray trace and wave-front analysis. Experiments are carried out to illustrate the effectiveness of this approach. The methods can work well, despite large deviation between the theoretic value of the aspheric and the reference wave-front
Academic innovation: are we truly ready for it?
Full text linkOptics has been in the headlines this year due to the UN-sponsored International Year of Light 2015 (IYL 2015), and due to its presence in the 2014 Nobel Prize awards. The purpose of this article is to highlight the innovation-enabling elements that were behind the work of one of the Nobel Laureates - and the stream of innovations that followed, beyond the Nobel work. I will further, from this and my personal experience, expand some thoughts on the enabling elements of academic innovation and draw some conclusions - and, in particular, try and answer the question “How can academic success be repeated?â
Development of a spectrometer for airborne measurement of droplet sizes in clouds
Full text linkThe objective of this article is to present the development and the validation in flight of an airborne probe that can measure in clouds the size of droplets whose diameters are in the range [20 µm; 200 µm]
Flat-gain wide-band erbium doped fiber amplifier by combining two difference doped fibers
Full text linkA new erbium-doped fibre amplifier (EDFA) is demonstrated using a combination of newly developed Erbium Zirconia co-doped fiber (Zr-EDF) and the commercial silica-based Erbium-doped fiber (Si-EDF) as the gain medium. Both fibers have a very high concentration of erbium ion. A compact amplifier operating in C-band region is firstly reported using a double-pass configuration. It is shown that average gains of the proposed Zr-EDF amplifier are obtained at approximately 18 dB with a gain variation of ±2 dB within C-band region. A flat-gain and wide band operation is achieved by configuring the amplifier in two stages comprising a 2 m long Zr-EDF and 9 m long Si-EDF optimised for C- and L-band operations, respectively, in a double-pass parallel configuration. A chirp fibre Bragg grating (CFBG) is used in both stages to ensure double propagation of the signal and thus to increase the attainable gain in both C- and L-band regions. At an input signal power of 0 dBm, a flat gain of 15 dB is achieved with a gain variation of less than 0.5 dB within a wide wavelength range from 1530 to 1605 nm. The corresponding noise figure varies from 6.2 to 10.8 dB within this wavelength region
Drift compensation using a multichannel slot waveguide Young interferometer
Full text linkPolymeric integrated Young interferometer sensor chips utilizing a slot waveguide have demonstrated to be sensitive, to work at visible wavelengths, to be manufacturable by simple process, and to have a reduced sensitivity to temperature fluctuations. Although slot waveguide Young interferometers have these desirable features for low-cost rapid diagnostics, the sensor readout is disturbed by mechanical drifts of the sensing system. In this paper we demonstrate that mechanical drifts of the readout system can be compensated by using a multichannel slot waveguide Young interferometer having two reference waveguides and applying a drift compensation method based on the analysis of the spatial shifts of the interferogram fringes. The applicability of the drift compensation method was studied by conducting experiments with undisturbed and with mechanically disturbed setup to measure the phase changes induced by the changes of the bulk refractive index. By applying the drift compensation method, the sample induced phase change responses were extracted from up to 18 times larger measured phase changes in the disturbed experiments proving the applicability of the method with multichannel slot waveguide Young interferometers
Effect of heat treatment on optical properties of crosslinkable Azo Chromophore doped in poly amic acid
Full text linkIn this work, we have studied the optical properties of a crosslinkable poly amic acid containing Disperse Red 1. The thin films were cured at 130, 160 and 195 °C. The structural and optical properties of the doped films were investigated by using UV-VIS spectra, and Prism Coupling techniques. The composite crosslinks during poling rendering it totally insoluble. A r33 of 1.5 pm/v was obtained after poling
Caustic region fields of an elliptical reflector covered by an anisotropic magnetized plasma layer
Full text linkTheoretical formulations of the electromagnetic (EM) field distribution in the focal or caustic region of an elliptical reflector with its curved surface coated by collisional magnetized anisotropic plasma have been derived. Both parallel and perpendicular polarizations of the normal incident wave are considered. Expressions for the EM field intensity along the focal region have been obtained accurately using Maslov’s method. The effect of the plasma-layer thickness on the reflected and transmitted field intensity distributions was investigated. Other physical parameters such as the plasma electron density, the cyclotron frequencies, and the collisional frequency have been noticed to have an evident influence on the levels of the transmitted field-intensities along the focal region. The problem discussed in this paper has, also, been solved using Kirchhoff’s approximation and the results of the two methods are found to be in a good agreement
Absorbance response of graphene oxide coated on tapered multimode optical fiber towards liquid ethanol
Full text linkThe investigation of graphene oxide (GO) for sensing applications is attractive due to its nanoscale structure and its sensing properties has yet to be fully understood. In this paper, optical response of GO coated optical fiber sensor towards ethanol is described. GO was coated onto a multimode tapered optical fiber by drop-casting technique. The coated fiber was exposed to 5–40% of ethanol in water. The films were characterized with field emission scanning electron microscope, ultraviolet-visible spectroscopy and Raman spectroscopy. The sensing is based on changes following the absorbance of the GO coated optical fiber upon exposure to ethanol. The developed sensor shows fast response and recovery with duration of 22 and 20 s, respectively. The sensor also displays high repeatability and reversibility
Improvement of performance and stability of polymer photovoltaic cells by WO3/CuPc as anode buffer layers
Full text linkIn this work, bulk-hetrojunction polymer photovoltaic cells based on poly-(3-hexylthiophene) (P3HT): [6,6]-phenyl C61 butyric acid methyl ester (PCBM) were fabricated with tungsten oxide (WO3) and copper phthalocyanine (CuPc) as anodic buffer layers. The WO3 plays an important role in reducing the interfacial resistance, efficiently extracting holes and good band structure matching between the work function of the anode and the highest occupied molecular orbital of the organic material. The insertion of CuPc improves the device In this work, bulk-hetrojunction polymer photovoltaic cells based on poly-(3-hexylthiophene) (P3HT): [6, 6]-phenyl C61 butyric acid methylester (PCBM) were fabricated with tungsten oxide (WO3) and copper phthalocyanine (CuPc) as anodic buffer layers. The WO3 plays animportant role in reducing the interfacial resistance, efficiently extracting holes and good band structure matching between the workfunction of the anode and the highest occupied molecular orbital of the organic material. The insertion of CuPc improves the deviceperformance and expands the absorption spectra range of the photovoltaic devices. The effects of WO3 and CuPc thickness on theperformance of the photovoltaic devices were investigated. The optimum thicknesses of WO3 and CuPc were 10 nm and 8 nm, respectively. The obtained power conversion efficiency of optimized cell was about 4.21%. Also, the device performance was analyzed based on thesurface roughness of bare ITO and ITO that was covered with poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) or WO3/CuPc. The device stability in an ambient atmosphere without encapsulation under continuous light irradiation was also investigated.For the cell with PEDOT:PSS, the power conversion efficiency reduced down to 50% of the maximum value (half-life) after light irradiationfor 12 h, while the half-life of device for WO3/CuPc was about 120 h. Therefore, the lifetime of unpackaged devices was improved with WO3/CuPc
Guided-mode triggered switching between TE orders of a metal-based grating-waveguide
Full text linkAn undulated metal-based dielectric slab waveguide is shown to exhibit a high contrast broadband switching effect in the angular spectrum between the 0^th order Fresnel reflection and the propagating -1^st reflected diffraction orders. The switching trigger is the synchronous collinear coupling of an incident TE plane wave to the close-to-cutoff forward- and backward-propagating fundamental TE_0 mode of the waveguide via the +1^st and -2^nd order of the periodic undulation