Writing Planar Optical Waveguide And Its Experimental Studybased On The LiNbO₃ Crystal

Since 1966,the photorefractive effect has been found in the LiNbO₃ crystal,applied research based on photorefractive effect has achieved rapid development.Writting planar optical waveguide in the photorefractive crystal is one of the many remarkable achievements of research and application of photorefractive crystal.Using conventional planar optical waveguide technology can obtain surface waveguide with the fine structure,but traditional waveguide process has many defects:complex technology?long cycle?high cost.The technique writting plane waveguide in photorefractive crystal is a rapid,direct,low cost,high benefit method of making optical waveguide.This article take the producing method,main class capacity is as follows:1)The photorefractive effect of LiNbO₃ crystal is the theoretical basis of this article research,First of all,this article illustrates the definition and characteristics of photorefractive effect,and the physical process of photorefractive.In addition this paper mainly discusses the process of photorefractive dynamics equation and charge field change caused by light in LiNbO₃ crystal.2)Modulating a light field with periodic intensity change is one focuse of this paper.In this paper,we using 532nm green laser modulate Fresnel double beam interference field at first;and then discuss the location of light source S in the double beam interference field,and consider the double prism is placed two way influence on interference light field;at last measure the wavelength of laser light source validation the correctness of interference light field.3)To avoid ambient light effect,selecting a darkroom to write planar waveguide in LiNbO₃ crystals.Method is putting the LiNbO₃ crystal samples in the double beam interference field modulation by a wavelength of 532 nm,20 mW power laser exposure15³0minutes.4)Measure the characteristics of planar waveguide written in the LiNbO₃ crystal samples:at first,measure the refractive index distribution in the crystal samples by shearing interferometric technique;and then,measure the planar optical waveguide cycle through the632 nm laser direct LiNbO₃ crystals samples,the last is to test different doped LiNbO₃ crystal light damage resistance.