An Experimental Study On Electro-optical Long-period Grating Based Upon Titanium-diffused Lithium Niobate Waveguide

Long period gratings in the field of sensing and light control has goodapplication prospect. A long-period grating in/on a waveguide structure, namedlong-period waveguide grating (LPWG).In comparison with the long-period fibergrating(LPFG),LPWG have a series of advantages. This article mainly study onelectro-optical long-period grating based upon titanium-diffusion lithium niobatewaveguide from the aspects of theory and experiment.The main work accomplished in this paper:1.To establish based on electro-optic effect of LPWG theory model and the requiredspecial waveguide mode refractive index model.2.Fabricate a special waveguide structure with strip waveguide array embedded in aplanar waveguide by twice titanium-diffusion method. Using a prism coupling systemto measure mode refractive index of waveguide in order to determine the period ofLPWG.And further completed the fork electrode mask fabrication.3.Use lithography technology to complete the production of titanium fork electrode.Then use of the experiment system characterized the resistance properties of EOLPWG. Studied relations that rejection band of LPWG dependence of driving voltage.4.The experimental results show that when the driving voltage exceeds100V,LPWG effect was observed. With the increase of the driving voltage, Rejection rateincreased gradually. When driving voltage up to150V,18dB rejection rate reachedthe maximum. As the driving voltage increases further, due to the over-coupling,rejection rate decreases with the increase of the driving voltage. Rejection bandposition almost does not change with the driving voltage.5.Get the most rejection rate experimental value of the driving voltage aresignificantly higher than the theoretical value. Causes of the differences mainly thewithout optimization the structure of the waveguide and electrode and withoutconsidering the polarization effect.In addition, other band-stop characteristics ofobserved, such as bandwidth, the qualitative interpretation of inhibition zone position.This paper work provides the basis of further research work.