Limits...
Switchable Ultrathin Quarter-wave Plate in Terahertz Using Active Phase-change Metasurface.

Wang D, Zhang L, Gu Y, Mehmood MQ, Gong Y, Srivastava A, Jian L, Venkatesan T, Qiu CW, Hong M - Sci Rep (2015)

Bottom Line: In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface.After the transition to metal phase, the quarter-wave plate operates at 0.502 THz.At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.

ABSTRACT
Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tunable/active and extremely low-profile polarization manipulation devices in the terahertz regime through the incorporation of such phase-change metasurfaces, enabling novel applications of ultrathin terahertz meta-devices.

No MeSH data available.


Related in: MedlinePlus

Temperature dependent behaviors of the fitting parameters and the flowchart for QWP design.(a) Analytical fitted geometric factors and (b) damping rates at different temperatures. (c) Fitted transmission spectra along y-axis at 300 and 400 K. (d) Fitted phase distributions along y-axis at 300 and 400 K. (e) A QWP design flowchart to optimize the parameters of the phase-change metasurfaces.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4595731&req=5

f4: Temperature dependent behaviors of the fitting parameters and the flowchart for QWP design.(a) Analytical fitted geometric factors and (b) damping rates at different temperatures. (c) Fitted transmission spectra along y-axis at 300 and 400 K. (d) Fitted phase distributions along y-axis at 300 and 400 K. (e) A QWP design flowchart to optimize the parameters of the phase-change metasurfaces.

Mentions: With a proper parameter fitting based on the experimental results, the transmission spectra and phase delays of the THz QWP are plotted in Fig. 2e,f, which is in good agreement with the measurement and simulation. The fitted geometric factor g and damping rate γ at different temperatures are plotted in Fig. 4a,b. It is observed that when the VO2 pads go through the phase transition, the geometric factors decrease dramatically, indicating a weak coupling between the incident THz wave and the VO2 metasurfaces. When the conductivity of VO2 further increases to its maximum point, the geometric factor slightly increases. The difference of gx and gy indicates different losses for and , which are consistent with the measured and simulated results. The damping rates plotted in Fig. 4b show that both γxand γy increase with temperature. To illustrate the correlation of the fitting parameters and the performance of QWP, the fitted transmission coefficients and phase distributions at 300 and 400 K along y-axis are plotted in Fig. 4c,d. It is observed that the decrease of geometric factors correlate with the decrease of transmission coefficients. The increase of damping rates leads to a large resonance bandwidth as the spectral phase dispersion tends to be flat.


Switchable Ultrathin Quarter-wave Plate in Terahertz Using Active Phase-change Metasurface.

Wang D, Zhang L, Gu Y, Mehmood MQ, Gong Y, Srivastava A, Jian L, Venkatesan T, Qiu CW, Hong M - Sci Rep (2015)

Temperature dependent behaviors of the fitting parameters and the flowchart for QWP design.(a) Analytical fitted geometric factors and (b) damping rates at different temperatures. (c) Fitted transmission spectra along y-axis at 300 and 400 K. (d) Fitted phase distributions along y-axis at 300 and 400 K. (e) A QWP design flowchart to optimize the parameters of the phase-change metasurfaces.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595731&req=5

f4: Temperature dependent behaviors of the fitting parameters and the flowchart for QWP design.(a) Analytical fitted geometric factors and (b) damping rates at different temperatures. (c) Fitted transmission spectra along y-axis at 300 and 400 K. (d) Fitted phase distributions along y-axis at 300 and 400 K. (e) A QWP design flowchart to optimize the parameters of the phase-change metasurfaces.
Mentions: With a proper parameter fitting based on the experimental results, the transmission spectra and phase delays of the THz QWP are plotted in Fig. 2e,f, which is in good agreement with the measurement and simulation. The fitted geometric factor g and damping rate γ at different temperatures are plotted in Fig. 4a,b. It is observed that when the VO2 pads go through the phase transition, the geometric factors decrease dramatically, indicating a weak coupling between the incident THz wave and the VO2 metasurfaces. When the conductivity of VO2 further increases to its maximum point, the geometric factor slightly increases. The difference of gx and gy indicates different losses for and , which are consistent with the measured and simulated results. The damping rates plotted in Fig. 4b show that both γxand γy increase with temperature. To illustrate the correlation of the fitting parameters and the performance of QWP, the fitted transmission coefficients and phase distributions at 300 and 400 K along y-axis are plotted in Fig. 4c,d. It is observed that the decrease of geometric factors correlate with the decrease of transmission coefficients. The increase of damping rates leads to a large resonance bandwidth as the spectral phase dispersion tends to be flat.

Bottom Line: In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface.After the transition to metal phase, the quarter-wave plate operates at 0.502 THz.At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.

ABSTRACT
Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tunable/active and extremely low-profile polarization manipulation devices in the terahertz regime through the incorporation of such phase-change metasurfaces, enabling novel applications of ultrathin terahertz meta-devices.

No MeSH data available.


Related in: MedlinePlus