Jerrett Vella from Wyle Aerospace group and AFRL introduced an ultracompact plasmonic modulator for Terahertz modulation, during which modulation up to 130 dB for the first time using a 15 um active area, which is 20 times smaller than the operation wavelength at 300 um.
Their approach first convert Terahertz waves propagating in the 3-D space to surface plamons propagating along a metal-photoconductive dielectric interface. Surface plasmons are known to have much smaller volume as well as strong interaction with the media. Thus, when a white light is illuminated on the photoconductive material when its charge carrier density as well as the dielectric permittivity changes, the property, the propagation constant in this case, of the surface plasmon also changes. When the THz surface plasmon is converted back to propagating THz waves using a second grating, the change in the propagation constant results in a change in the direction of the propagating THz waves. Such beam steering capability is a beautiful demonstration of plasmonic modulator which can realize high performance with a device volume much much smaller than the wavelength of the THz wave.
Posted: 10/8/2013 3:58:51 PM by
By Zhimin Shi
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