Active Metamaterials for Terahertz Communication and Imaging
Rout, Saroj.
2016
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Abstract: In recent years there has been significant interest in terahertz
(THz) systems mostly due to their unique applications in communication and imaging. One of
the primary reason for this resurgence is the use of metamaterials to design THz devices
due to lack of natural materials that can respond to this electromagnetic spectrum, the
so-called ''THz gap''. Even after years of intense re... read moresearch, THz systems are complex and
expensive, unsuitable for mainstream applications. This work focuses on bridging this gap
by building all solid-state THz devices for imaging and communication applications in a
commercial integrated circuit (IC) technology. One such canonical device is a THz wave
modulator that can be used in THz wireless communication devices and as spatial light
modulator (SLM) for THz imaging systems. The key contribution of this thesis is a
metamaterial based THz wave modulator fabricated in a commercial gallium arsenide (GaAs)
process resonant at 0.46~THz using a novel approach of embedding pseudomorphic high
electron mobility transistors (pHEMTs) in metamaterial and demonstrate modulation values
over 30%, and THz modulation at frequencies up to 10 MHz. Using the THz wave modulator, we
fabricated and experimentally demonstrated an all solid-state metamaterial based THz
spatial light modulator (SLM) as a 2x2 pixel array operating around 0.46 THz, by raster
scanning an occluded metal object in polystyrene using a single-pixel imaging setup. This
was an important step towards building an low-voltage (1V), low power, on-chip integrable
THz imaging device. Using the characterization result from the THz SLM, we computationally
demonstrated a multi-level amplitude shift keying (ASK) terahertz wireless communication
system using spatial light modulation instead of traditional voltage mode modulation,
achieving higher spectral efficiency for high speed communication. We show two orders of
magnitude improvement in symbol error rate (SER) for a degradation of 20 dB in transmit
signal-to-noise ratio (SNR). We have computationally demonstrated a novel pictorial
modulation technique showing N/log2(N) improvement in bandwidth using a N-tile SLM compared
to standard spatial modulation using a single-pixel detector. Finally, we demonstrate a
path to realize a terahertz focal plane array (FPA) using a commercial 0.18 um CMOS foundry
process. Through EM simulation and circuit simulation we have demonstrated a metamaterial
based THz detectors at 230-325 GHz that can be used in a focal plane
array.
Thesis (Ph.D.)--Tufts University, 2016.
Submitted to the Dept. of Electrical Engineering.
Advisor: Sameer Sonkusale.
Committee: Mohammed Afsar, Shuchin Aeron, Xiaocheng Jiang, and Edward Lee.
Keywords: Electrical engineering, Electromagnetics, and Physics.read less - ID:
- ns064j74v
- Component ID:
- tufts:21287
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- DCA Citation Guide EndNote
