Propagation of Photons Through Localized Coupled Cavity Modes in Photonic Band Gap Structures:

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1 CLEO, May 7-12, , San Francisco Propagation of Photons Through Localized Coupled Cavity Modes in Photonic Band Gap Structures: A New Type of Waveguiding Mechanism Mehmet Bayındır Burak Temelkuran and Ekmel Özbay Bilkent University, Department of Physics

2 Outline Review of layer-by by-layer three-dimensional photonic crystals Tight binding description of the coupled cavities Experimental observation of the eigenmode splitting Determination of the tight-binding parameters Observation of a new type of waveguiding mechanism: Coupled-cavity waveguides (CCW) Straight CCWs Bent CCWs Zig-zag CCWs Observation of heavy photons at the CCW band edges Group velocity tends towards to zero Photon lifetime increases drastically Possible applications of the CCWs

$Material: Alumina of refractive index ε =3.1 at microwave frequencies Dimensions: 0.32 cm 0.32 cm 15.25 cm Three-dimensional stop band: from 10.6 GHz to 12.8 GHz E. Ozbay, J. Opt. Soc. Am.$

3 Layer-by by-layer Three-Dimensional Photonic Crystals Power (db) Reflection Transmission Frequency (GHz) Symmetry: Face centered tetragonal (fct) Material: Alumina of refractive index ε =3.1 at microwave frequencies Dimensions: 0.32 cm 0.32 cm cm Three-dimensional stop band: from 10.6 GHz to 12.8 GHz E. Ozbay, J. Opt. Soc. Am. B 13, 1945 (1996)

Tight-Binding Description of Localized Coupled Defect Modes Tight-binding parameters can be directly determined from experiments N. Stefanou and A.

4 Tight-Binding Description of Localized Coupled Defect Modes Tight-binding parameters can be directly determined from experiments N. Stefanou and A. Modinos, Phys. Rev. B 57, (1998) A. Yariv et al., Opt. Lett. 24, 711 (1999) Mehmet Bayindir, B. Temelkuran, and E. Ozbay, Phys. Rev. Lett. 82, 2140 (2000)

5 Experimental Setup HP 8510C

6 Localized Coupled-Cavity Cavity Modes: Splitting Transmission (arb. units) Q=1000 Ω = GHz ω 1 = GHz ω 2 = GHz Γ 1 = GHz Γ 2 = GHz Γ 3 = GHz Frequency (GHz) 13.5 The tight-binding parameter can be determined from the splitting of two coupled-cavity cavity modes Mehmet Bayindir, B. Temelkuran, and E. Ozbay, Phys. Rev. Lett. 82, 2140 (2000)

7 Straight CCW: Transmission Characteristics Propagation of the electromagnetic waves through localized coupled-cavity cavity modes: A new type of waveguiding mechanism The tight-binding parameter can also be determined from the bandwidth of CCW band Transmission (db) Perfect Crystal Coupled-Cavity Waveguide Frequency (GHz) No loss, No backreflections Full transmission was measured throughout the CCW band

8 Straight CCW: Dispersion Relation Experiment Theory ω k / Ω Tight-binding approximation: k Λ / π

Straight CCW: Group Velocity and Photon Lifetime v g / c 0.04 0.03 0.02 0.01 Experiment Theory Photon Lifetime (ns) 40 30 20 10 0 Experiment Theory 0.00 0.00 0.25 0.

9 Straight CCW: Group Velocity and Photon Lifetime v g / c Experiment Theory Photon Lifetime (ns) Experiment Theory k Λ / π Frequency (GHz) at the CCW band edges heavy photon Mehmet Bayindir and E. Ozbay, Phys. Rev. B 62, R2247 (2000)

10 40 o Bent CCW: Transmission Characteristics The problem of how to guide light around small structures seems s to be a difficult task when conventional waveguides are used. 0 Possibility of constructing lossless and reflectionless bends in optical circuits Transmission (db) Frequency (GHz) Nearly 100 % transmission was measured throughout the CCW band

11 Nearly 100 % transmission was measured throughout the CCW band Zig-Zag Zag CCW: Transmission Characteristics Arbitrarily shaped path with a constant intercavity distance 0 Transmission (db) Frequency (GHz)

12 Zig-Zag Zag CCW: Dispersion Relation and Group Velocity Experiment Theory 0.04 Experiment Theory ω k / Ω 1.00 v g / c k Λ / π k Λ / π Mehmet Bayindir, B. Temelkuran, and E. Ozbay, Phys. Rev. B 64, (2000)

13 Possible Applications of CCWs Small group velocity and long photon lifetime: Increasing efficiency of nonlinear optical process, second harmonic generation, stimulated emission,... Sharp transitions in the transmission spectrum: Switching applications,... A new propagation mechanism: Lossless and reflectionless guiding and bending of light around sharp corners in optical circuits,... Coupled-cavity RCE photodetectors: High efficiency for wide range of resonance wavelengths

14 What about optical wavelengths? Our experimental and theoretical results for coupled-cavity cavity optical waveguides (CCOW) will be presented at OSA Annual Meeting 2000.

15 Acknowledgments These works are supported by Turkish Department of Defence Grant No. KOBRA-01 Turkish Scientific and Technical Research Council of TURKEY (TUBITAK) under Contract No. 197-E044 NATO Grant No. SfP National Science Foundation Grant No. INT NATO-Collaborative Research Grant No

Photonic crystals: a novel class of functional materials

Materials Science-Poland, Vol. 23, No. 4, 2005 Photonic crystals: a novel class of functional materials A. MODINOS 1, N. STEFANOU 2* 1 Department of Physics, National Technical University of Athens, Zografou