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Unfolding the band structure of non-crystalline photonic band gap materials.

Tsitrin S, Williamson EP, Amoah T, Nahal G, Chan HL, Florescu M, Man W - Sci Rep (2015)

Bottom Line: Our results demonstrate the existence of sizeable PBGs in these disordered structures and provide detailed information of the effective band diagrams, dispersion relation, iso-frequency contours, and their angular dependence.Slow light phenomena are also observed in these structures near gap frequencies.This study introduces a powerful tool to investigate photonic properties of non-crystalline structures and provides important effective dispersion information, otherwise difficult to obtain.

View Article: PubMed Central - PubMed

Affiliation: San Francisco State University, San Francisco, CA, 94132 USA.

ABSTRACT
Non-crystalline photonic band gap (PBG) materials have received increasing attention, and sizeable PBGs have been reported in quasi-crystalline structures and, more recently, in disordered structures. Band structure calculations for periodic structures produce accurate dispersion relations, which determine group velocities, dispersion, density of states and iso-frequency surfaces, and are used to predict a wide-range of optical phenomena including light propagation, excited-state decay rates, temporal broadening or compression of ultrashort pulses and complex refraction phenomena. However, band calculations for non-periodic structures employ large super-cells of hundreds to thousands building blocks, and provide little useful information other than the PBG central frequency and width. Using stereolithography, we construct cm-scale disordered PBG materials and perform microwave transmission measurements, as well as finite-difference time-domain (FDTD) simulations. The photonic dispersion relations are reconstructed from the measured and simulated phase data. Our results demonstrate the existence of sizeable PBGs in these disordered structures and provide detailed information of the effective band diagrams, dispersion relation, iso-frequency contours, and their angular dependence. Slow light phenomena are also observed in these structures near gap frequencies. This study introduces a powerful tool to investigate photonic properties of non-crystalline structures and provides important effective dispersion information, otherwise difficult to obtain.

No MeSH data available.


Related in: MedlinePlus

Simulated transmission and accumulated actual phase in the square lattice (a,c) and HUD (b,d) as function of frequency and incident angle for the structures analyzed in Fig. 2.
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f3: Simulated transmission and accumulated actual phase in the square lattice (a,c) and HUD (b,d) as function of frequency and incident angle for the structures analyzed in Fig. 2.

Mentions: Figure 3a,b show the calculated color contour plots of the transmission, and Fig. 3c,d show the calculated color contour plots of the accumulated phase as a function of frequency and incident angle for the square lattice and the HUD structure, respectively. These simulation results mirror the experimentally obtained data presented in Fig. 2a–d. The measured data presented in Fig. 2 covers the frequency range from 15 to 35 GHz, which corresponds to the frequency range of 0.33 to 0.77 (c/a) in Fig. 3. A small number of artifacts are still present in Figs 2 and 3, caused by errors in tracking phase jumps of 2π at the lower and upper band edges where phase data becomes increasingly random.


Unfolding the band structure of non-crystalline photonic band gap materials.

Tsitrin S, Williamson EP, Amoah T, Nahal G, Chan HL, Florescu M, Man W - Sci Rep (2015)

Simulated transmission and accumulated actual phase in the square lattice (a,c) and HUD (b,d) as function of frequency and incident angle for the structures analyzed in Fig. 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4542607&req=5

f3: Simulated transmission and accumulated actual phase in the square lattice (a,c) and HUD (b,d) as function of frequency and incident angle for the structures analyzed in Fig. 2.
Mentions: Figure 3a,b show the calculated color contour plots of the transmission, and Fig. 3c,d show the calculated color contour plots of the accumulated phase as a function of frequency and incident angle for the square lattice and the HUD structure, respectively. These simulation results mirror the experimentally obtained data presented in Fig. 2a–d. The measured data presented in Fig. 2 covers the frequency range from 15 to 35 GHz, which corresponds to the frequency range of 0.33 to 0.77 (c/a) in Fig. 3. A small number of artifacts are still present in Figs 2 and 3, caused by errors in tracking phase jumps of 2π at the lower and upper band edges where phase data becomes increasingly random.

Bottom Line: Our results demonstrate the existence of sizeable PBGs in these disordered structures and provide detailed information of the effective band diagrams, dispersion relation, iso-frequency contours, and their angular dependence.Slow light phenomena are also observed in these structures near gap frequencies.This study introduces a powerful tool to investigate photonic properties of non-crystalline structures and provides important effective dispersion information, otherwise difficult to obtain.

View Article: PubMed Central - PubMed

Affiliation: San Francisco State University, San Francisco, CA, 94132 USA.

ABSTRACT
Non-crystalline photonic band gap (PBG) materials have received increasing attention, and sizeable PBGs have been reported in quasi-crystalline structures and, more recently, in disordered structures. Band structure calculations for periodic structures produce accurate dispersion relations, which determine group velocities, dispersion, density of states and iso-frequency surfaces, and are used to predict a wide-range of optical phenomena including light propagation, excited-state decay rates, temporal broadening or compression of ultrashort pulses and complex refraction phenomena. However, band calculations for non-periodic structures employ large super-cells of hundreds to thousands building blocks, and provide little useful information other than the PBG central frequency and width. Using stereolithography, we construct cm-scale disordered PBG materials and perform microwave transmission measurements, as well as finite-difference time-domain (FDTD) simulations. The photonic dispersion relations are reconstructed from the measured and simulated phase data. Our results demonstrate the existence of sizeable PBGs in these disordered structures and provide detailed information of the effective band diagrams, dispersion relation, iso-frequency contours, and their angular dependence. Slow light phenomena are also observed in these structures near gap frequencies. This study introduces a powerful tool to investigate photonic properties of non-crystalline structures and provides important effective dispersion information, otherwise difficult to obtain.

No MeSH data available.


Related in: MedlinePlus