In response to ever growing data traffic, significant efforts are being made to increase optical network capacity.
One promising candidate is mode-division multiplexing (MDM) in few-mode fibers, which uses space as a new
information-bearing dimension. A fundamental element for MDM is a modal transformer. Modal transformation
can be implemented in a free-space basis by using multi-region phase plates. In this work we present the design,
fabrication and characterization of monolithic binary phase plates by highly-uniform Ag+/Na+ ion-exchange in
glass. Diffracted optical field intensities have been measured and high quality mode transformation has been
confirmed.
In this work is presented a macroscopic quantum-mechanical analysis of quantum light progression in different
kinds of integrated photonic waveguide structures with coupled modes, and therefore with validity, for instance,
for integrated optical waveguides (conventional integrated optics), photonic crystal waveguides, nano-optical
waveguides (plasmonic modes) and so on. The main goal of the work is to give a consistent and explicit derivation
of the quantum Momentum operator, and therefore to calculate the corresponding Heisenberg's Equations.
Quantum propagation of nonclassical light states are analyzed in different linear and nonlinear integrated devices.
In this work we present an analysis of the propagation, based on the Dirac equation, of spinor-electron quantum
modes, that is, of spinor-electron guided waves in asymmetric 2D and 1D semiconductor nanostructures.
Spinor-electron modes are calculated by means of Dirac equation in an asymmetric 2D semiconductor structures,
analogous to the wellknown optical modes of the conventional integrated optics; moreover, by means of standard
methods well stablished in integrated photonics, such as Marcatili method or Knox-Toulios method, 1D electron
waveguides are studied. The study of these nanoelectronic devices based on electron waveguides in semiconductors
is directed to understand better the possibilities of linking between nanoelectronic and nanophotonic
devices.
In this work we present the study of step-index channel directional couplers which can be fabricated on a buffer planar guide in a such a way that they can be properly designed to support separable modal fields, though the index profile is non separable. The main advantage of this approach is the great simplicity in the analysis, design and
fabrication of the directional couplers, or other different integrated strucutures, since it is possible to apply, for instance, the effective index method obtaining a quasi-exact solution for the modal fields. Analytical and numerical results will be presented to confirm that an accurate design of the operation properties of the
directional coupler can be achieved.
A nonlinear integrated optical device, presenting an intrinsic bistable behaviour by means of the Kerr effect produced by counterpropagating beams, is presented. The proposed feedback mechanism, which preserves the spatial shape of the beams, is based on the transverse modal coupling of the beams to optical fibers through integrated multilenses. An optimum waveguiding design is presented to allow both the fabrication of this device by hybrid
integration on glass and show the results of bistability.
Ion-Exchanged Glass Integrated Optics has received a considerably attention during the laser years because of their well-known advantages. On the other hand, ion- exchanged waveguide components are finding important applications in the implementation of analogue processing devices, optical sensing devices and some kind of circuit for optical communications. Many of these develop devices are based on channel guides, however planar components with optical confinement in only one dimension have been also recognized to be among the basic components of glass integrated optics. In this paper we show the specific advantages of using these kinds of integrated optical elements. Thus, conventional photolithographic techniques can be used with a great accuracy but within the high requirements needed for channeled devices. Likewise, as it will be shown, the components can be realized by simple selective ion-exchange processes in a few steps, and with a high transmission of guided light, in a monomode regime, through the various boundaries shaping the planar components. Finally, their planar configuration facilitates considerably the use of glass integrated devices with other materials and thus a high-performance hybrid optical devices can be achieved. In short, we show various approaches to the design and fabrication of planar components and presents several passive components implementing simple functions such as: beam-splitting, focusing, and so on, which are important for optical sensing and processing applications.
We present a technique to directly process silver ion- exchanged planar waveguides fabricated in soda-lime glass. The technique, that is regarded as complementary to the conventional lithography but with the inherent advantages of the direct processing of the material, is based on laser writing with a focused laser bema from an Ar+ laser, which induces a redistribution and aggregation of the small sliver clusters created in the glass during the ion-exchange process. We give a theoretical explanation of the physical processes that take place in the glass and expose experimental reslut of processing of silver ion-exchanged guides under different irradiation conditions. We expose the possible applications of this technique to integrated optics for 2D waveguiding, to optoelectronics for one-step electrode and waveguide fabrication, to planar optics for patterning of reflective components and to diffractive optics to fabricate conventional elements. We finally demonstrate some of this applications presenting devices fabricated by means of this technique.
A simple, effective and low cost laser writing lithographic system is presented. This system with a simple optical design and interferometric control of the alignment is able to produce smallest optical features as 1 micrometers wide with high quality edges to produce prototypes of integrated optical elements by ion exchange in research laboratories. Results of several kinds of mask that can be generated for this systems as well as some of the integrated elements produced are shown.
Non linear ion-exchange at surface and post-annealing processes are presented in a combined form to fabricate waveguide elements. Variational approaches are used to determine both the index profiles achieved and their waveguiding characteristics. Relationships between optical and fabrication parameters are derived. Their usefulness to both fabrication and designing of waveguide elements is shown.
It is known that the ion-exchange process in glass is described by a non linear diffusion equation whose solutions represent the index profile of the waveguide formed. The diffusion equation depends on the relative mismatch of the incoming and original ion mobilities, characterized by the parameter (alpha) . If they are equal, the diffusion equation becomes linear, and its solutions are normally used as an approximation for non-linear processes. Nevertheless, empirical solutions often provide a better modelization, but they must be found in each particular case of diffusion. In this work, we develop a perturbative method for solving the non linear equation, thus approximated analytical solutions can be obtained up to intermediate (alpha) -values ((alpha) equals 0.5). We have applied it to a simple surface thermal waveguide. By another hand, a proper dependent variable change is performed in the diffusion equation, and then the perturbative method is applied. It provides a solution much more exact that can be used with great accuracy up to (alpha) equals 0.8, which is a situation where Gaussian functions are normally used as empirical solutions. The method can be applied to more complex situations as buried waveguides, field-assisted processes and so on.
Lateral ion-exchange, arising in the fabrication of waveguide elements by masking techniques, is modelized. The effective index method is used in order to analyze the effects on the light transmission when the side diffusion creates an effective graded index transition. Preliminary results are presented by using both a wave and geometrical approaches in the paraxial region. They show that the lateral ion-exchange modifies the paraxial parameters and it must be taken into account when the system's aberrations are corrected.
An analytical modelling of buried waveguides is presented. These waveguides are fabricated by a purely thermal ion back diffusion in glass, which is enhanced by applying an electric field across the substrate. The model is based on an approximation of low ionic concentration with arbitrary variation, in such a way that an approximate nonlinear diffusion equation can be solved under different boundary and initial conditions.
The preliminary results of a round-robin test to check the reproducibility of the measurement of the main optical characteristics of gradient-like planar waveguides are reported. The test involves seven research laboratories in Europe and Canada. The effective indexes of a set of planar waveguides produced by K+/Na+ ion-exchange have been measured in each laboratory and the refractive-index profiles have been reconstructed by various numerical methods. The comparison between the reconstructed profiles and the directly measured one is also shown for one of the waveguides under test.
GRIN media characterized by a hyperbolic secant profile of the refractive index (HSPRI) have been widely analyzed by geometrical optics and it is well known that these media are free of aberrations for meridional rays." This behaviour provides optimum transmission capabilities and optical transformations such as focusing and collimation.
We propose a new metrologic application of zone plates, using interferometric techniques, in order to detect changes in the refraction index of a dielectric parallel plate under the influence of the environmental parameters. The key of this kind of interferometer is a couple of circular zone plates produced with the proper combination of initial phase shift, in order to suppress the constant phase factors introduced with the system in the equilibrium state. In this way we are in quadratic condition and then we can measure the variation parameters with great accuracy and with the advantage of knowing the sign of it produced under external actions. The influence of the several fabrications parameters are discussed.
Use of GRIN Fiber Lenses as SMF-to-SMF connectors is analyzed.
Coupling conditions are derived under Gaussian mode approximation in
order to obtain maximum coupling efficiency.
We present results for the Modal Coupling Efficiency among the different regions of an Integrated Optical Device module fabricated in LiNbO3 by using numerical and variational calculations.
We analyze the exact Fresnel diffraction in a GRIN Fiber Lens (GFL) due to its finite extent when it is illuminated by a modal gaussian illumination. Its influence in Single Mode Fibers (SMF) interconnections is shown.
Colllaating and Focusing operations of icrolenses (N) arrays coupled to a channel waveguide (U) array have been optimized for its use in integrated optical device aodules.
Coupling efficiency optimization in a multichannel device composed by a SingleMode Fiber (51fF) array coupled to a GRIN Fiber Lens (FL) array is studied. Curves of coupling efficiency limited by diffraction in each pair GFLSMF is analyzed.
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