A Polygonal Model to Design and Fabricate Ion-Exchanged Diffraction Gratings

Carlos Montero-Orille,Xesús Prieto-Blanco,Jesús Liñares,Héctor González-Núñez

doi:10.3390/app11041500

Carlos Montero-Orille, Xesús Prieto-Blanco + Show 2 more

Open Access

https://doi.org/10.3390/app11041500

Copy DOI

Journal: Applied sciences	Publication Date: Feb 7, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: University of Santiago de Compostela

Abstract

We propose a simple polygonal model to describe the phase profile of ion-exchanged gratings. This model enables the design of these gratings, as well as the characterization of the ion-exchange process itself. Several ion-exchanged gratings were fabricated to validate the model and to characterize the process involved in their fabrication. From this characterization, we show the practical utility of the model by designing and fabricating both a grating that removes the zero order and a three splitter. The performance of these two elements was good, although the first one stood out especially because only 0.5% of the power remained in the zero order after diffraction. This polygonal model could be useful to design more complex diffractive elements.

Highlights

Diffractive Optical Elements (DOEs) are widely used in different fields such as holography [1], spectroscopy [2], astronomy [3], and so on
Ion-exchange changes the refractive index of suitable substrates, typically in a region of some micrometers under its surface
We propose a simple polygonal model for the phase profile achieved following thermal ion-exchange processes

Summary

Introduction

Diffractive Optical Elements (DOEs) are widely used in different fields such as holography [1], spectroscopy [2], astronomy [3], and so on. The gratings with this kind of profile have significant advantages They can be mathematically analyzed by closed-form expressions. By designing appropriate masks, as well as the ion-exchange process itself, different kinds of phase gratings have been fabricated [6,7]. We propose a simple polygonal model for the phase profile achieved following thermal ion-exchange processes This model enables the design and fabrication of grating elements in a simple way. After characterization of the ion-exchange process by using such a model, different grating elements can be designed and fabricated . Cancellation of the zero order of diffraction is desirable in many applications of diffractive elements, such as digital holography [8], spatial light modulation [9], and grating fabrication [10], among others. Light splitting is useful, in general, for power division tasks [11], and in particular, it has been used, combined with other phase functions, in the fabrication of vortex gratings [12]

Objectives

Methods

Findings

Conclusion