Terahertz Frequency Multiplier Operation of Two Dimensional Plasmon Resonant Photomixer

Takuya NISHIMURA  Mitsuhiro HANABE  Masaki MIYAMOTO  Taiichi OTSUJI  Eiichi SANO  

IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.7   pp.1005-1011
Publication Date: 2006/07/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.7.1005
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM2005)
Category: THz Devices
plasmon resonance,  photomixer,  terahertz,  multiplier,  grating,  

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We analytically investigated the feasibility of multiplier operation in the terahertz range for our original plasmon resonant photomixer. The photomixer features two unique structures (doubly interdigitated gate gratings and a vertical cavity) for higher radiation efficiencies. Its total field emission properties are the result of a combination of plasmon excitation dynamics and electromagnetic field dynamics. The plasmon excitation formulated by the hydrodynamic equations exhibits fundamental and harmonic resonances whose intensities monotonically decrease with the number of harmonics due to the dispersive plasma damping factors. The electromagnetic dynamics, on the other hand, formulated by the Maxwell's equations, reflect material- and structure-dependent device parameters; the grating-bi-coupled plasmonic cavity together with the vertical cavity structures produce nonlinear field emission properties. This results in extraordinary field enhancement at distinct frequencies inconsistent with the plasmon resonances. The frequency-dependent FDTD (finite difference time domain method) Maxwell's simulation revealed that the field emission peak frequency shifted upward apart from the fundamental mode of plasmon resonant frequency and approached to its second harmonic frequency with increasing the electron density in the plasmon cavity. Calculated total field emission spectra indicated that highly dense 2D-plasmon conditions enable frequency-doubler operation in the terahertz range.