Photonic Eigenmodes in a Photonic Crystal Membrane (original) (raw)
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Journal of Lightwave Technology, 2011
Coupled resonator photonic crystal devices may find important applications in future integrated nanophotonic circuits. These devices are well suited for coupling of mode analysis, which usually requires much less computational resources compared with finite-difference time domain (FDTD) schemes. Coupled mode models also provide a useful physical insight in the device operation. In this paper, we present a general coupled mode theoretic model for the treatment of coupled cavity devices incorporating various phenomena such as dispersion, frequency variation of the coupling coefficients, nonadjacent cavity coupling, and waveguide mode self coupling. The model is validated comparing its results against the FDTD method and the strength of the underlying assumptions is highlighted. Various approximations that can lead to further simplification of the coupled mode model are also discussed. It is shown that, unless the device transfer function possesses very sharp resonances, coupled mode analysis can provide an accurate device description. Index Terms-Coupled mode analysis, finite-difference time domain (FDTD), integrated optics, optical waveguides.
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UPB Scientific Bulletin, Series A: Applied Mathematics and Physics
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Photonic Crystal Materials and Devices X, 2012
Sub-micron waveguides and cavities have been shown to produce the confinement of elastic and optical waves in the same devices in order to benefit from their interaction. It has been shown that square and honeycomb lattices are the most suitable to produce simultaneous photonic and phononic band gaps on suspended silicon slabs. The introduction of line defects on such "phoxonic" (or optomechanical) crystals should lead to an enhanced interaction between confined light and sound. In this work we report on the experimental measurements of light guiding through waveguides created in these kinds of two-dimensional photonic crystal membranes. The dimensions of the fabricated structures are chosen to provide a "phoxonic" bandgap with a photonic gap around 1550 nm. For both kinds of lattice, we observe a hightransmission band when introducing a linear defect, although it is observed for TM polarization in the honeycomb lattice and for TE in the square. Using the plane-wave expansion and the finite element methods we demonstrate that the guided modes are below the light line and, therefore, without additional losses beside fabrication imperfections. Our results lead us to conclude that waveguides implemented in honeycomb and square lattice "phoxonic" crystals are a very suitable platform to observe an enhanced interaction between propagating photons and phonons.
Frequency control of photonic crystal membrane resonators by monolayer deposition
We study the response of GaAsphotonic crystal membrane resonators to thin-film deposition. Slow spectral shifts of the cavity mode of several nanometers are observed at low temperatures, caused by cryo-gettering of background molecules. Heating the membrane resets the drift and shielding will prevent drift altogether. In order to explore the drift as a tool to detect surface layers, or to intentionally shift the cavity resonance frequency, we studied the effect of self-assembledmonolayers of polypeptide molecules attached to the membranes. The 2-nm-thick monolayers lead to a discrete step in the resonance frequency and partially passivate the surface.
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Synthetic Metals, 2003
Recent experimental and theoretical work on two-dimensional (2D) and waveguide-embedded photonic crystals is reviewed. The investigated systems are 2D macroporous silicon and photonic crystal slabs based on silicon-on-insulator as well as GaAs/AlGaAs. In all these structures, reflectance at varying angles of incidence allows to determine the dispersion of photonic modes above the light line. For macroporous silicon, reflectance from the side yields a complementary measurement of the photonic gaps. In the GaAs-based system, second-harmonic generation in reflection shows a resonant enhancement when the pump beam is frequency-and momentum-matched to a photonic mode in the slab. A theory of photonic states in waveguide-embedded photonic crystals leads to a determination of mode dispersion and diffraction losses for leaky photonic modes.
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Optics Communications, 2017
An optical setup, inspired from that used for angle resolved reflective spectra measurement is used to determine photonic bands dispersion of 2D photonic crystals for all-around observation. The observation relies on coupling between the incoming beam and the photonic modes in periodically patterned planar structure, generating resonant features in the optical spectra. The features as a function of specific azimuthal angle lead to the determination of in-plane wave vector at a given frequency. To probe a performance of the photonic structures, the optical response of the photonic crystal in radiative region above light line was determined, and the structure of leaky modes for both polarization planes TE, TM at several incident angles was mapped. Leaky modes structure was approved by numerical RCWA-based modelling. The measured azimuthal dependences were evaluated to obtain equi-frequency curves.