Tunable subwavelength focusing with slit-groove-based metamaterials in THz

We design the THz lens made of slit-groove-based metamaterials with tunable far-field focal length as well as subwavelength resolution, based on surface plasmons(SP) diffraction theory into spoof SP of THz region. In THz regime, the curved depth profile of grooves from both sides of metal slit produce directional beaming and mimic SP at the same time. By arranging the depth of grooves in traced profile, it is possible to optimize the focal position in THz region without changing the size of structure. It is performed numerical simulation of a designed structure through finite-difference time-domain (FDTD) method and shows the subwavelength imaging of the designed position. In addition, the change of focal length and the relative Ex phase are observed in the simulation and help to comprehend a subwavelength 1D slit-groove-based metamaterials in THz regime.

[1]  四方 潤一,et al.  Terahertz-wave near-field imaging with subwavelength resolution using surface-wave-assisted bow-tie aperture , 2006 .

[2]  H. Lezec,et al.  Theory of highly directional emission from a single subwavelength aperture surrounded by surface corrugations. , 2003, Physical review letters.

[3]  Chunlei Du,et al.  Focal length modulation based on a metallic slit surrounded with grooves in curved depths , 2007 .

[4]  Masayoshi Tonouchi,et al.  Cutting-edge terahertz technology , 2007 .

[5]  Tzong-Jer Yang,et al.  Terahertz surface plasmon polaritons on periodically corrugated metal surfaces. , 2008, Optics express.

[6]  Stefan A Maier,et al.  Terahertz surface plasmon-polariton propagation and focusing on periodically corrugated metal wires. , 2006, Physical review letters.

[7]  Chih-Kung Lee,et al.  Physical origin of directional beaming emitted from a subwavelength slit , 2005 .

[8]  H. Lezec,et al.  Extraordinary optical transmission through sub-wavelength hole arrays , 1998, Nature.

[9]  Dai-Hyuk Yu,et al.  Tunable subwavelength focusing with dispersion-engineered metamaterials in the terahertz regime. , 2010, Optics letters.

[10]  J. Pendry,et al.  Surfaces with holes in them: new plasmonic metamaterials , 2005 .

[11]  Changtao Wang,et al.  Surface electromagnetic wave excitation and diffraction by subwavelength slit with periodically patterned metallic grooves. , 2006, Optics express.

[12]  R. J. Bell,et al.  Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared. , 1983, Applied optics.

[13]  J. Pendry,et al.  Mimicking Surface Plasmons with Structured Surfaces , 2004, Science.