The inverse Doppler effect in photonic crystal with negative refractive index had been proofed experimentally in our previous research. In this paper, we studied the spatial harmonics of Bloch wave propagating in such PhCs by FFT method. The lagging and front phase evolutions reveal that both backward wave and forward wave exist in these harmonics. Subsequently, we studied the double Doppler effect phenomenon that both the normal and inverse Doppler exist in one photonic crystal simultaneously by using the improved dynamic FDTD method which we made it suitable for dealing with moving objects. The simulative Doppler frequency shifts were consistent with the theoretical values. Our study provides a potential technology in measurement area.
The analysis of the temperature property of sensors based on symmetrical metal-cladding optical waveguide (SMCOW) is focused on analyzing the temperature property of reflectivity of SMCOW sensors, which is theoretically studied with single-factor investigation under spectral and angular interrogation scheme. There are mainly four factors influencing the temperature dependence of reflectivity, it is the temperature dependence of refractive index and thickness of guiding layer, along with the temperature dependence of the metal film thickness and metal-dielectric function. The simulation result shows that the effect of temperature on the reflectivity of SMCOW is mainly attributed to the temperature dependence of refractive index and thickness of guiding layeron the contrary, the temperature properties of metal film hardly contributes to the influence of temperature on the reflectivity. Based on the analysis, the sensitivities of SMCOW with guiding layer of different optical glasses are computed under both spectral and angular interrogation. This paper is supposed to provide direction in designing temperature-sensitive SMCOW structure sensors.