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Register a new userTunable temporal gap based on simultaneous fast and slow light in electro-optic photonic crystals
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We demonstrated a tunable temporal gap based on simultaneous fast and slow light in electro-optic photonic crystals. The light experiences an anomalous dispersion near the transmission center and a normal dispersion away from the center, where it can be accelerated and slowed down, respectively. We also obtained the switch between fast and slow light by adjusting the external electric filed. The observed largest temporal gap is 541 ps, which is crucial in practical event operation inside the gap. The results offer a new solution for temporal cloak.
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In this work we describe different types of photonic structures that allow tunability of the photonic band gap upon the application of external stimuli, as the electric or magnetic field. We review and compare two porous 1D photonic crystals: in the first one a liquid crystal has been infiltrated in the pores of the nanoparticle network, while in the second one the optical response to the electric field of metallic nanoparticles has been exploited. Then, we present a 1D photonic crystal made with indium tin oxide (ITO) nanoparticles, and we propose this system for electro-optic tuning. Finally, we describe a microcavity with a defect mode that is tuned in the near infrared by the magnetic field, envisaging a contact-less magneto-optic switch. These optical switches can find applications in ICT and electrochromic windows.
We have investigated the tunable lateral shift and polarization beam splitting of the transmitted light beam through electro-optic crystals, based on the Pockels effect. The positive and negative lateral shifts could be easily controlled by adjusting the permittivity tensor, which is modulated by the external applied electric field. An alternative way to realize the polarization beam splitter was also proposed by the polarization-dependent lateral shifts. Numerical simulations for Gaussian-shaped incident beam have demonstrated the above theoretical results obtained by stationary phase method. All these phenomena have potential applications in optical devices.
Slow-light enhanced optical detection in liquid-infiltrated photonic crystals is theoretically studied. Using a scattering-matrix approach and the Wigner-Smith delay time concept, we show that optical absorbance benefits both from slow-light phenomena as well as a high filling factor of the energy residing in the liquid. Utilizing strongly dispersive photonic crystal structures, we numerically demonstrate how liquid-infiltrated photonic crystals facilitate enhanced light-matter interactions, by potentially up to an order of magnitude. The proposed concept provides strong opportunities for improving existing miniaturized absorbance cells for optical detection in lab-on-a-chip systems.
A fast, switchable electro-optic radial polarization retarder (EO-RPR) fabricated using the electro-optic ceramic PMN-PT is presented. This EO-RPR is useful for fast, switchable generation of pure cylindrical vector beam. When used together with a pair of half-wave plates, the EO-RPR can change circularly polarized light into any cylindrical vector beam of interest such as radially or azimuthally polarized light. Radially and azimuthally polarized light with purities greater than 95% are generated experimentally. The advantages of using EO-RPR include fast response times, low driving voltage and transparency in a wide spectral range (500 -7000 nm).
The model of nonlinear interaction of proper waves of photonic crystal with plane acoustic wave was developed. The formulation of the model is reduced to the eigenvalue problem, which can be solved by computer simulations. By means of the formulae given in present paper one can predict which polarizations of acoustic wave can result in Bragg diffraction of optical waves of TE or TM polarizations. Computer simulation allows obtaining amplitudes of interaction waves in the case of Bragg diffraction when phase-matching conditions are fulfilled.
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