Shape Of Transmission Spectrum Research Articles

Study on the Fano resonance of coupling M-type cavity based on surface plasmon polaritons

Abstract The metal–insulator–metal (MIM) waveguide structure consisting of an M-type cavity and a baffle is proposed. Through the interaction between the discrete state and the continuous state by the M-type cavity and the baffle, the structure possesses a distinctly sharp asymmetric Fano resonance line. For positive M-type cavity structure, the shape of transmission spectrum can be adjusted by the structure parameters. The wavelength of the resonant peak has a linear relation with the length and width of the cavity, and has very good flexibility in the design and adjustment of structure. The ultra-sharp spectrum contributes to the sensitivity of structure which can reach up to 760nm/RIU and the maximum figure of merit is 9 . 9 × 1 0 4 . For improved symmetrical M-type cavity structure, the simulation results show that the sensitivity reaches 780nm/RIU and the maximum figure of merit is 1 . 56 × 1 0 5 . Its performance has been further enhanced. The structure may have a number of important applications in the field of nano-sensors.

Transmission of asymmetric coupling double-ring resonator

Based on the asymmetry between waveguide and double ring, the transmission and phase characteristics of coupled double-ring resonators are analyzed systemically. It is shown that the initial detuning determines the shape of transmission spectrum. The transmission spectrum of all-optical analog to electromagnetic inducted transparency (EIT) is controlled by tuning the asymmetric coupled parameter and loss. With the increasing of asymmetric coupled parameter, the transmission spectrum changes from EIT-like profile to Lorenz profile. The EIT-like transmission spectrum results from the interference between two Lorenz profiles. With the increasing of the loss, the transmission spectrum full frequency width at half-maximum broadens and its peak declines. The detuning and loss also make significant influences on the phase profile.

Electric field effects on exciton in the shape of transmission spectra in high-purity GaAs at room temperature

The electric field effects on the shape of transmission spectra associated with exciton including continuum band transition in ultra-high-purity GaAs have been theoretically studied at room temperature. We have calculated the Stark red shift, linewidth broadening of exciton, height of exciton peak and extinction ratio with applied electric field. The theoretical results are compared with experimental and found the close agreement between them.

Enhanced Middle-Infrared Light Transmission Through Au/SiOxNy/Au Aperture Arrays

The enhanced middle-infrared light transmission through Au/SiO(x)N(y)/Au aperture arrays by changing the refractive index and the thickness of a dielectric layer was studied experimentally. The results indicated that the transmission spectra was highly dependent on the refractive index and the thickness of SiO(x)N(y). We found that the transmission peaks redshifted regularly along with the refractive index from 1.6 to 1.8, owing to the role of surface plasmon polaritons (SPP) coupling in the Au/SiO(x)N(y)/Au cascaded metallic structure. Simultaneously, a higher transmission efficiency and narrower transmission peak was obtained in Au/SiO2.1N0.3/Au cascaded metallic structure with small refractive index (1.6) than in Au/SiO0.6N1/Au cascaded metallic structure with large refractive index (1.8). When the thickness of SiO(x)N(y) changes from 0.2 to 0.4 microm, the shape of transmission spectra exhibits a large change. It was found that a higher transmission efficiency and narrower transmission peak was obtained in Au/SiO(x)N(y)/Au cascaded metallic structure with a thin dielectric film (0.2 microm), with the increase of SiO(x)N(y) film's thickness, the transmission peak gradually widened and disappeared finally. This effect is useful in applications of biochemical sensing and tunable integrated plasmonic devices in the middle-infrared region.

Tailoring optical transmission via the arrangement of compound subwavelength hole arrays

The transmission properties of light through metal films with compound periodic subwavelength hole arrays is numerically investigated by using the finite-difference time-domain (FDTD) method. The sharp dips in the transmission bands, together with the suppression of surface Plasmon resonance (SPR) (0, 1) peak, are found when two square holes in every unit cell are arranged asymmetrically along the polarization direction of the incident light. However, the shape of transmission spectra is not sensitive to the symmetry if the holes are arranged perpendicular to the propagation direction of surface plasmon polaritons (SPPs). The physics origin of these phenomena is explained qualitatively by the phase resonance of SPPs.