Sharif Digital Repository

We present an analytical method for solution of one-dimensional optical systems, based on the differential transfer matrices. This approach can be used for exact calculation of various functions including reflection and transmission coefficients, band structures, and bound states. We show the consistency of the WKB method with our approach and discuss improvements for even symmetry and infinite periodic structures. Moreover, a general variational representation of bound states is introduced. As application examples, we consider the reflection from a sinusoidal grating and the band structure of an infinite exponential grating. An excellent agreement between the results from our differential... 

A new formulation for the solution of wave propagation in inhomogeneous optical systems, based on the extension of conventional differential-transfer matrices into modified differential-transfer matrices, is given. In justification of our proposed method, several examples are presented, and the greater accuracy of our modified differential transfer matrices compared with that of conventional differential-transfer matrices is observed in several cases. It is also shown that the modified differential-transfer-matrix method is accurate enough even in those cases that the conventional differential-transfer-matrix method fails to yield acceptable results. © 2005 Optical Society of America  

Optical fibers, in particular, glass fibers, are mostly used in the field of optical communication, however in recent years new optical sensors based on the optical fibers have been reported in literature and produced commercially. Extrinsic and intrinsic character of the fibers have been implemented in development of such sensing devices. Glass Optical Fibers (GOF) because of low attenuation are more suitable for the optical communication purposes while Plastic Optical Fibers are advantageous for the linking purpose and some sensing operations. Considering this point different (POF) optical fiber sensors have been developed by author to show potential applications of POFs in sensor... 

Thin films of (WO3)1 - x-(Fe2O 3)x composition were deposited by thermal evaporation on glass substrates and then all samples were annealed at 400 °C in air. Optical properties such as transmittance, reflectance, and optical bandgap energy of the "as deposited" and the annealed films were studied using ultraviolet-visible spectrophotometry. It was shown that the annealing process did not substantially change the optical transmittance and reflectance of all the films except the films having x = 0.75. By increasing Fe2O 3 content in the films from x = 0 to x = 0.75, optical bandgap energy decreased from 3.4 to about 1.3 eV and from 3.1 to 2.1 eV for the "as deposited" and the annealed samples,... 

The roughness of glass surfaces after different stages of etching is investigated by reflection measurements with a spectrophotometer, light scattering, atomic force microscopy (AFM, on a small scale) and profilometry (on a large scale). The results suggest that there are three regimes during etching, according to their optical reflectivity and roughness. The first and the second regimes are studied by the Kirchhoff theory and the third one is studied by the optical geometric theory. Also, the roughness obtained by optical scattering is compared with the AFM results. Copyright © 2005 John Wiley & Sons, Ltd  

Design and performance of a two-stage optical beam shaping system based on a plastic fiber-bundle prism-coupled waveguide is described in this study. Such systems offer practical means to modify and change the output beam shape at two stages and also provide quantitative information concerning the output beam intensity profile. It is possible to obtain reflection and image transmittance data by using a light source for the illumination and image analysis by a CCD/digital camera. Using the active lighting, the reflection data and image profiles for the output beam are obtained by a CCD camera and presented in this study. The photograph picture of the illuminating LED beam just at its output... 

Operation of an optomechanical system for color reflection study is reported. The reported system consists of a double-fiber optical design and an electro-mechanical scanning system. In the double-fiber arrangement one fiber transmits the source light to the target surface and the second one sends the reflected light off the sample target to a photodetector. By scanning the double-fiber probe in one-direction reflection properties of different color liquid samples are investigated in this study. A cubic cell made of glass material is used as the liquid container and reflection signals are compared for different filled color liquids. The maximum reflection signals are: for the yellow color... 

Determination of the surface structure using the light reflection is an important issue. The aim is to study such surface reflections using an opto-mechanical system. The effects of the fiber arrangements in the operation of an opto-pair probe system for surface profiling are described. The opto-mechanical testing system consists of a double-fiber optical probe design and an electro-mechanical scanning system. Reflection signals for the plane and cylindrical surfaces made with different curvatures and materials are investigated with both probes and the results are compared. The reflection signal for the plane surface is independent of the double-fiber orientation in probe but for the curves... 

In this study surface profiling is performed by using a scanning system and an opto-pair fiber design. In this method one fiber transmits the laser light to the target and the second one transmits back the light reflected off the target to a photodetector. The monitoring of the reflected light signal from a surface is accomplished by converting the photon light into an electric signal and measuring by a digital multimeter. By scanning an object mounted on a XYZ-translational stage the reflection signal profiles are obtained for plane and curved surfaces. Output reflection signal variations in the X-, Y-, and Z-directions are measured for different plane and cylindrical surfaces and compared....