Mechanism Analysis And Experimental Study Of The Abnormal Physical Effect In Photonic Crystal With Negative Index

The negative refractive index materials challenge human's Conventional understanding in many traditional scientific area.The photonic crystal,which is easier to make than other negative index material,can also realize the negative refraction.Light propagation in photonic crystal with negative refractive index will occur abnormal physical phenomena,this has been studied widely in theoretical and experimental approach,and some of the abnormal physical phenomena has been used in our live successfully.However,to discover much more potential applications of negative index photonic crystal so as to promote the scientific progress and social development,the basic theory of light propagation in photonic crystal remain to be research furtherly.The inverse Doppler effect in photonic crystal had been proved experimentally,but its physical mechanism remain to reveal.The negative Goos-Hanchen shift on in surface of negative index photonic crystal had also been studied theoretically,however,measurement experiment of the negative Goos-Hanchen shift in two-dimensional photonic crystal has not been seen yet.Therefore,the thesis is focus on these two abnormal physical phenomena,and makes a deep theoretical and experimental research in them.By using the Fullwave module of Rsoft softwave,the field distribution of light propagation in photonic crystal is obtained,and the harmonics in Bloch wave is extracted from the field distribution data.The forward waves and backward waves is extracted after analyzing the phase evolution of these Bloch wave components.The continuous moving process is divided into several static moments,and the beat frequencies is obtained by analyzing the relationship of phase between each adjacent moment.Furthermore,the limitation of total reflection is breaked by altering the angle of slope and the incident direction,thus leads to the predication of the novel dual Doppler effect,which the normal Doppler effect and inverse Doppler effect happen simultaneously.To simulate the propagation of light in moving photonic crystal,the FDTD method is improved in this way,the parameters of the structure moves several grids during each period of iterative operation step,and the initial field data in each iterative operation step is updated with the data of former step.The results of the dual Doppler effect obtained by the improved FDTD method is compared with the theoretical value calculated with the effective refractive index which related to the extracted harmonics.With the error lower than 2%,the inverse Doppler effect can be illustrated as the result of backward wave in the photonic crystal,in addition,the result exhibits that the improved FDTD method is a useful approach to deal with the issue of light propagation in moving objects.The photonic crystal used to measure the inverse Goos-Hanchen shift is fabricated with a high aspect ratio,along with an uneven diameter down along the height direction.Before the measurement of Goos-Hanchen shift,the simulation is done with FDTD method,and the negative refraction is verified experimentally.The negative GoosHanchen shift is measured at three angles of 26 degrees,28 degrees and 32 degrees by fitting the reflectied field distribution with Gaussian function.The measurement is relatively consistent with the simulative result,and the smallest different between the negative Goos-Hanchen shift and positive Goos-Hanchen shift is measured as-33?m.