Terahertz photoconductive antenna with metal nanoislands.

This work presents a nanoplasmonic photoconductive antenna (PCA) with metal nanoislands for enhancing terahertz (THz) pulse emission. The whole photoconductive area was fully covered with metal nanoislands by using thermal dewetting of thin metal film at relatively low temperature. The metal nanoislands serve as plasmonic nanoantennas to locally enhance the electric field of an ultrashort pulsed pump beam for higher photocarrier generation. The plasmon resonance of metal nanoislands was achieved at an excitation laser wavelength by changing the initial thickness of metal film. This nanoplasmonic PCA shows two times higher enhancement for THz pulse emission power than a conventional PCA. This work opens up a new opportunity for plasmon enhanced large-aperture THz photoconductive antennas.

[1]  K. Kawase,et al.  Non-destructive terahertz imaging of illicit drugs using spectral fingerprints. , 2003, Optics express.

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

[3]  Prashanth C. Upadhya,et al.  Ultrabroadband terahertz radiation from low-temperature-grown GaAs photoconductive emitters , 2003 .

[4]  Ryoichi Fukasawa,et al.  Direct evidence of inter-molecular vibrations by THz spectroscopy , 2005 .

[5]  D. Grischkowsky,et al.  Terahertz time-domain spectroscopy of water vapor. , 1989, Optics letters.

[6]  P. Kohl,et al.  Gallium arsenide passivation through nitridation with hydrazine , 1993 .

[7]  Vladimir M. Shalaev,et al.  Searching for better plasmonic materials , 2009, 0911.2737.

[8]  Jong Chul Ye,et al.  Enhancement of terahertz pulse emission by optical nanoantenna. , 2012, ACS nano.

[9]  E. Linfield,et al.  Terahertz pulse imaging in reflection geometry of human skin cancer and skin tissue. , 2002, Physics in medicine and biology.

[10]  P. Petit,et al.  Effect of Hydrogen Pressure on the Size of Nickel Nanoparticles Formed during Dewetting and Reduction of Thin Nickel Films , 2010 .

[11]  Thomas Dekorsy,et al.  High-intensity terahertz radiation from a microstructured large-area photoconductor , 2005 .

[12]  K. Catchpole,et al.  Plasmonic solar cells. , 2008, Optics express.

[13]  M. Tani,et al.  Emission characteristics of photoconductive antennas based on low-temperature-grown GaAs and semi-insulating GaAs. , 1997, Applied optics.

[14]  V. Wallace,et al.  Biomedical applications of terahertz technology , 2006 .

[15]  Wenzel,et al.  Decay times of surface plasmon excitation in metal nanoparticles by persistent spectral hole burning , 2000, Physical review letters.

[16]  A. Tünnermann,et al.  Terahertz line detection by a microlens array coupled photoconductive antenna array. , 2008, Optics Express.

[17]  Shikuan Yang,et al.  Template‐Confined Dewetting Process to Surface Nanopatterns: Fabrication, Structural Tunability, and Structure‐Related Properties , 2011 .

[18]  M. Jarrahi,et al.  Plasmonically-enhanced localization of light into photoconductive antennas , 2010, CLEO/QELS: 2010 Laser Science to Photonic Applications.

[19]  Ki-Hun Jeong,et al.  Glass Nanopillar Arrays with Nanogap‐Rich Silver Nanoislands for Highly Intense Surface Enhanced Raman Scattering , 2012, Advanced materials.

[20]  G. Si,et al.  Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer , 2012 .