ABSTRACT
We report the use of laser ablation of metal targets onto a glass substrate as a way of producing waveguiding devices. In the geometry employed, the nanosecond pulses used for the ablation pass through the glass substrate, and are focused on the metal surface, which is located in close proximity with the substrate. We present measurements of the refractive index profile obtained with this technique, and present a discussion of the physical mechanisms that produce the profiles measured.
ABSTRACT
An interpretation of the Talbot effect in a tapered gradient-index medium by number theory as the output/input relationship between the integer and the noninteger difference of position and the slope of rays is presented. Unit cell and transverse magnification for Talbot images are evaluated, and two criteria for angular magnification are defined. The study is particularized to a finite set of diffracted rays.
ABSTRACT
We present a general formulation based on the Jones-matrix theory for reciprocal nonabsorbing polarization devices, including polarization interference filters and liquid-crystal displays. The development of this formulation is based on general symmetry conditions that relate the Jones matrix when the device is illuminated from the front side and from the back side. The application to liquid-crystal displays results in a constraint of the Jones-matrix elements, which represents a generalization of the existing models that explain their modulation properties.
ABSTRACT
A generalization of the fractional Talbot effect to the case of a tapered gradient-index medium for uniform illumination is considered. A unit cell of the fractional Talbot image contains the superposition of unit cell images of the periodic object.
ABSTRACT
Nonparaxial diffraction-limited propagation of light with amplitude distribution in hyperbolic functions through an inhomogeneous planar medium with a hyperbolic secant refractive-index profile is studied by means of the stationary phase method. The irradiance distribution at geometrical shadow, edge of shadow, and a geometrically illuminated region is analyzed for a particular case.
ABSTRACT
The refractive indices of planar silver-ion-exchanged waveguides have been modified by UV excimer laser irradiation (lambda=193 nm) . The effective index changes of the fundamental modes of the waveguides after exposition are as large as 2x10(-2) . The procedure permits the fabrication of integrated optical components in a direct way, with neither the use of standard lithography nor previous sensitizing of the substrate. Optical characterization of the irradiated samples is presented. By the use of appropriate masks, we have fabricated planar Bragg gratings.
ABSTRACT
The characteristic dimensions of Bessel beams are fully determined by the corresponding Bessel functions. We consider a way of obtaining a narrower diameter of the central core of a diffractive pattern generated by the Bessel beams. The method relies on superposition of two or more Bessel beams with appropriately chosen amplitudes and widths. The disturbing influence of the aperture's edges can be eliminated by addition of the proper amplitude filter.
ABSTRACT
An analysis of the butt-joining coupling between two inhomogeneous planar optical waveguides with hyperbolic secant refractive-index profiles is made from the point of view of geometrical optics. Furthermore, the design of a new device to contract or expand a collimated beam is presented, and a relationship between sizes of the input and output beams is obtained.
ABSTRACT
The axial intensity of axicons illuminated by a coherent wave usually exhibits rapid oscillations from diffraction on the sharp edges of the aperture of the element. These oscillations can be suppressed when the diffractive version of the axicon is illuminated from a polychromatic source. This possibility is examined based on the example of the annular-aperture logarithmic axicon. The estimate for the wavelength interval of the illuminating source required for uniformization is obtained with the help of the stationary-phase method. Furthermore the shape of the radial intensity distribution can be maintained almost unchanged. These findings are confirmed by numerical evaluation of the Fresnel diffraction integral.
ABSTRACT
This feature of Applied Optics publishes papers related to the theme of the GRIN '92 Topical Meeting that was held in Santiago de Compostela, Spain, 4-6 October 1992. This introduction gives a brief explanation of gradient-index components and defines the scope of the feature.
ABSTRACT
Unconventional imaging and focusing properties are obtained when odd powers of the radial coordinate are present in a radial gradient-index profile. We calculate the transmittance function for this kind of medium under a paraxial approximation by a quasi-geometrical approach. Likewise, we analyze the pupil effect; that is, we evaluate the intensity distribution diffracted by a gradient-index axicon at the image plane.
ABSTRACT
Light transmission through a gradient-index medium, whose refractive-index profile can be represented by a one-dimensional hyperbolic secant function, is analyzed by a wave-optics approach. An asymptotic expression of the corresponding optical propagator (the Green's function) in this medium is evaluated in a such a way that nonparaxial propagation can be studied. Thus optical transformations such as focusing and collimation are obtained, and the pupil effect (diffractive effect) is shown.
ABSTRACT
Three-dimensional focal curves generated by one-dimensional gradient-index taper have been obtained when the taper is illuminated by an off-axis plane wave. The intensity distribution along the focal curve was evaluated by taking into account the particular form of the exit pupil produced by this gradient-index medium.
ABSTRACT
The general solution presented here yields smooth, continuous, and monotonic refractive-index profiles for Luneburg-Morgan lenses with a boundary index of N > 1. The new formula incorporates an original apparent-immersing method as well as the continuous-deflection-function concept recently developed by one of the authors for the description of waveguide lenses.
ABSTRACT
Diode lasers are often used as light sources for transmitting information through optical fibers. One of the inherent properties of this kind of laser is the astigmatism. Therefore, in applications that require focusing, an anamorphic system is needed. We present a theoretical study for the design of an anamorphic gradient-index lens to correct the astigmatism of the elliptical Gaussian beams emitted by diode lasers.
ABSTRACT
A preliminary study on focal curves generated by one-dimensional gradient-index tapers is presented. An asymptotic wave method is applied to derive the optical propagator and to solve propagation in these inhomogeneous media.
ABSTRACT
Arbitrary modal field coupling is analyzed and optimized by using tapered and nontapered GRIN fiber lenses as single-mode optical fiber connectors. Conditions for achieving maximum coupling efficiency are derived.
ABSTRACT
An equilateral hyperbolic zone plate has been recorded by coherent superimposition of two cylindrical waves with coplanar foci. This zone plate has been used to align quickly and easily a Mach-Zehnder interferometer.
