Study On The Vernier Effect Of Symmetrical Metal Cladding Waveguide

Optical waveguide is a kind of component that restricts and propagates light in integrated optical path.The symmetrical metal-cladding waveguide has a unique structure compared with the special traditional waveguide,which substrates and overlays are both metal,and guide wave is in the middle.Because the dielectric constant of precious metals is negative in the visible or infrared such as gold and silver.Meanwhile,the incident light can be coupled directly by air through the upper metal film into the guided wave layer to realize free space coupling.And its structure doesn't require the coupling of prism and grating.When the thickness of the waveguide layer reaches sub-millimeters,the ultra-high-order guide mode can be excited,which is very sensitive to parameters' change in the waveguide layer.To boost the sensing sensitivity further,this paper proposes a veriner effect based on symmetrical metal-cladding waveguide.Therefore,the specific research in this paper is as follows:In the first place,we study the vernier effect based on double polarization and single-cavity,then achieve the high sensitivity measurement of temperature.Next,the anisotropic liquid crystal material injecting into the guided wave layer.When the incident light is linear polarized light that theta is 45? because of the refractive index of the material is polarization dependent.The optical path between the TE and the TM polarization is different,which results in the reflection spectrum of different periods and the difference between the two periods is very small.As a result,the reflection spectrum with vernier effect is generated by the superposition of two reflection spectra,the free range is observed to be larger.Theoretical analysis that temperature changes,not only the refractive index of LC materials changes in guide layer,but also the reflection spectrum with vernier effect has been shifted greatly.The results show that the production of vernier effect makes the sensitivity enhanced by the temperature adjusted.Finally,we research the high sensitivity measurement of magnetic field intensity based on the vernier effect in wavelength scanning.The basic step is put laser wavelength of the light source to scan over time.Then,by means of current adjust magnetic field intensity,the refractive index of the magneto-optical material will change slightly by adjusting that causes the movement of reflectance spectra.It is found that the vernier effect spectrum moves faster can improves the magnetic field sensitivity sensing and measurement,relative to the non-scan spectrum.It is worth noting that different scanning points will affect the sensitivity of magnetic field sensing.