wavelength-division demultiplexing by superimposed gratings (supergrating) in a planar waveguide is modeled, accounting for intergrating coupling, and a theoretical decoupling criterion that serves as a guideline for ...
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wavelength-division demultiplexing by superimposed gratings (supergrating) in a planar waveguide is modeled, accounting for intergrating coupling, and a theoretical decoupling criterion that serves as a guideline for practical design is presented. Superimposed gratings were formed by direct photoinscription in a photosensitive silica planar waveguide, which is a promising method for practical optical circuit applications. A 1 x 8 channel wavelength-division multiplexer is demonstrated experimentally as a proof-of-concept study. The effects on experimental performance of wavelength-selectivity broadening and finite photosensitive index-modulation depth are discussed. (C) 1997 Optical Society of America.
We introduce a Z-scan technique as a tool to characterize small phase shift (< 1 rad) and photodarkening, both effects induced inside photosensitive materials by light illumination. Theoretical analysis supported b...
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We introduce a Z-scan technique as a tool to characterize small phase shift (< 1 rad) and photodarkening, both effects induced inside photosensitive materials by light illumination. Theoretical analysis supported by experiments is presented for permanent refraction and absorption Gaussian profiles. Simple relations are derived in order to estimate the changes in the linear coefficients. Particularly, we investigate quantitatively the photoinduced modifications in the linear optical constants of As(2)S(3) caused by subbandgap irradiation (17 ps, 1064 nm). (C) 2009 Optical Society of America
Optical waveguide structures have been fabricated on polysilicon-on-insulator. Structural and optical properties of the waveguides are studied by X-ray diffraction, atomic force microscopy, scanning electron microscop...
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Optical waveguide structures have been fabricated on polysilicon-on-insulator. Structural and optical properties of the waveguides are studied by X-ray diffraction, atomic force microscopy, scanning electron microscopy, and transmission measurements. Reasons for the waveguide loss are discussed. It is found that surface roughness can be responsible for a waveguide loss of more than 60 dB cm(-1) and that additional loss mechanisms probably exist. Methods of smoothing the surface are discussed. (C) 2003 Kluwer Academic Publishers.
Oxygen-doped lithium fluoride crystals were colored electrolytically by using a pointed cathode and a flat anode at various temperatures and electric field strengths, which mainly benefit appropriate coloration temper...
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Oxygen-doped lithium fluoride crystals were colored electrolytically by using a pointed cathode and a flat anode at various temperatures and electric field strengths, which mainly benefit appropriate coloration temperatures and electric field strengths as well as anode structure of used electrolysis apparatus. Characteristic spectral bands of O2--V-a(+) dipoles and O2--V-a(+) dipole complexes and magnesium-related F, M, magnesium-perturbed F-2(+), oxygen-perturbed F-2(+), F-3(-) color centers were observed in absorption spectra of the colored crystals. Current-time curves for the electrolytic colorations and their relationships with the electrolytic coloration processes were given. Color-center formation in the electrolytic coloration was explained. (c) 2006 American Institute of Physics.
The concept, design and realisation of integrated uniplanar antenna-mixer and MESFET local oscillator is presented in this paper. All circuits are realised on one side of the dielectric substrate in coplanar waveguide...
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The concept, design and realisation of integrated uniplanar antenna-mixer and MESFET local oscillator is presented in this paper. All circuits are realised on one side of the dielectric substrate in coplanar waveguide technique (CPW). Isotropic conversion gain is more than 4 dB better and bandwidth is broader than in the solution known so far. Presented circuits are also more simple for realisation.
A coplanar waveguide radial line stub resonator is experimentally characterised with respect to stub radius, sectoral angle, substrate thickness and relative dielectric constant. A simple closed-form design equation, ...
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A coplanar waveguide radial line stub resonator is experimentally characterised with respect to stub radius, sectoral angle, substrate thickness and relative dielectric constant. A simple closed-form design equation, which predicts the resonance radius of the stub, is presented.
We report highly versatile nanosensors using polymer single nanowires. On the basis of the optical response of waveguiding polymer single nanowires when exposed to specimens, functionalized polymer nanowires are used ...
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We report highly versatile nanosensors using polymer single nanowires. On the basis of the optical response of waveguiding polymer single nanowires when exposed to specimens, functionalized polymer nanowires are used for humidity sensing with a response time of 30 ms and for NO2 and NH3 detection down to subparts-per-million level. The compact and flexible sensing scheme shown here may be attractive for very fast detection in physical, chemical, and biological applications with high sensitivity and small footprint.
Guided-wave directional couplers having good polarisation-maintaining characteristics have been made in glass and assembled with polarisation maintaining fibre arrays fabricated by a novel technique using capillaries ...
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Guided-wave directional couplers having good polarisation-maintaining characteristics have been made in glass and assembled with polarisation maintaining fibre arrays fabricated by a novel technique using capillaries on a V-grooved substrate. The extinction ratios of the output ports were over 31 dB for waveguide chips and 26 dB for fibre array-assembled devices, respectively.
Two new techniques for exciting a linearly tapered slot antenna (LTSA) with coplanar waveguide (CPW) are introduced. In the first approach, an air bridge is used to couple power from a CPW to an LTSA. In the second ap...
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Two new techniques for exciting a linearly tapered slot antenna (LTSA) with coplanar waveguide (CPW) are introduced. In the first approach, an air bridge is used to couple power from a CPW to an LTSA. In the second approach, power is electromagnetically coupled from a finite CPW (FCPW) to an LTSA. Measured results at 18 GHz show excellent return loss and radiation patterns.
The use of thin polymer films in optical planar integrated optical circuits is rapidly increasing. Much interest, therefore, has been devoted to characterizing the optical and mechanical properties of thin polymer fil...
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The use of thin polymer films in optical planar integrated optical circuits is rapidly increasing. Much interest, therefore, has been devoted to characterizing the optical and mechanical properties of thin polymer films. This study focuses on measuring the elasto-optical properties of three different polymers;polystyrene, polymethyl-methacrylate, and benzocyclobutane. The out-of-plane elastic modulus, refractive index, film thickness, and birefringence of thin polymer films were determined by means of the prism coupling technique. The effect of the applied stress on the refractive index and birefringence of the films was investigated. Three-dimensional finite element method analysis was used so as to obtain the principal stresses for each polymer system, and combining them with the stress dependent refractive index measurements, the elasto-optic coefficients of the polymer films were determined. It was found that the applied stress in the out-of-plane direction of the thin films investigated leads to negative elasto-optic coefficients, as observed for all the three thin polymer films. (C) 2004 American Institute of Physics.
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