Research On Refractive Index Sensor In Three-dimensional Structure

After many years of research,the optical device miniaturization in low dimensional photonic crystals has tended to be perfect.And the optical device integration has also attracted more attention.Compared with one-dimensional and two-dimensional photonic crystals,three-dimensional photonic crystals have more important physical properties and more adjusted methods.Therefore,the research for the devices and their integration in three-dimensional structures is important particularly.Firstly,the refractive index sensor in woodpile structure is studied and analyzed by finite difference time domain method.The results show that the sensitivity,which is 2.06mm/RIU,is the highest when the size of the one cavity is 2.5a.And the two cavities are also considered.The results show that the maximum sensitivity is 2.46mm/RIU when the size of the two cavities are 2a and 2a,respectively.Secondly,the refractive index sensor in 2D-3D structure is also studied.Firstly,the sensing performance in two-dimensional photonic crystals are designed,simulated and analyzed.The results show that the sensitivity is up to S=2.10?m/RIU when the dielectric column is square and the defect cavity is composed of two dielectric columns;the sensitivity is up to S=4.00?m/RIU when the dielectric column is elliptical and the defect cavity is composed of four dielectric columns.Good sensing characteristics can be achieved.Then,we embedded the two-dimensional structure of square dielectric cylinder into the woodpile structure to form a two-dimensional-three-dimensional structure.The sensing performance of the two-dimensional structure with different size and number of microcavities was simulated and calculated.The sensing sensitivity of S=986 nm/RIU was realized in the defective cavity composed of four dielectric cylinders.The sensitivity of S=775 nm/RIU sensor is realized after three defect cavities with a 2a interval are constructed.Finally,the sawtooth waveguide is designed,simulated and analyzed in woodpile structure by finite difference time domain method.The results show that the guide band moves obviously when the adjacent sawtooth size is changed.For example,when the size of the long sawtooth is fixed,the guide band range narrows with the decreasing gradually of the size short sawtooth.And the high-frequency band edge and the low-frequency band edge move along the opposite direction.By contrary,when the size of the short sawtooth is fixed,the guide band moves to the high-frequency with the increasing continuously of the long sawtooth.The bend sawtooth waveguides and the Y-type wavelength division multiplexer including of the sawtooth waveguides are also designed,simulated and analyzed.The results show that the well transmission characteristics and the frequency selection are observed.