Shumei Song

Phase-sensitive Bloch surface wave sensor based on variable angle spectroscopic ellipsometry

In this paper, we propose a phase-sensitive Bloch surface wave sensor based on the variable angle spectroscopic ellipsometry and numerically simulate the phase behavior of the sensor. The simulation results show that the dependence of resonant phase is step-like when BSWs are excited. In contrast to the reflectance behavior, even though losses of the dielectric layers are very small, the resonance dip in the reflectivity will be shallow while the step-like change of the reflection phase of the BSW still be remarkable. This means that phase detection is an alternative to reflectivity intensity detection for the sensing applications of the BSWs in this case. Our experimental results indicate that phase detection for the BSW sensors has the potential to achieve the higher sensitivity and the lower limit of detection.

Phase properties of Bloch surface waves and their sensing applications

We study the phase properties of Bloch surface waves (BSWs) on truncated one-dimensional photonic crystals and find an abrupt change of the phase induced by BSWs. The phase of the BSW device shows a prominent response to the refractive index changes of the environment under resonance conditions. Furthermore, we demonstrate that the phase sensitivity of the BSW device is higher by nearly 1 order of magnitude than its amplitude sensitivity in terms of the figure of merit. This means that phase detection can be utilized to enhance the sensitivity of the BSW devices.

Structure of Co-Doped Alq3 Thin Films Investigated by Grazing Incidence X-ray Absorption Fine Structure and Fourier Transform Infrared Spectroscopy

The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.

Broad flattop transparent photonic band in truncated photonic crystals composed of the symmetric unit cell

We theoretically show that a one-dimensional finite all-dielectric periodic structure composed of symmetric unit cells can possess a broad flattop transparent photonic band. In contrast to the conventional viewpoint that the thickness of the truncated photonic crystals affects the transmission within the pass band, the transparent photonic band is insensitive to the change of the periodic number since the equivalent refractive indices of our structures can be nearly equal to that of the background in a wide frequency range. With easy fabrication, this broad flattop transparent photonic band will play an important role in the broadband filtering.