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DTSTAMP:20261021T161830Z
LAST-MODIFIED:20141124T172921Z
DTSTART:20141204T153000Z
DTEND:20141204T163000Z
UID:event1362@bu.edu
URL:http://physics.bu.edu/internal/events/show/1362
SUMMARY:Near Field Interactions in Terahertz Metamaterials
DESCRIPTION:Featuring George R. Keiser\n\nPart of the PhD Final Oral Exams.
	\n\nDissertation Committee: Richard Averitt\, David Bishop\, Claudio Chamon
	\, Xin Zhang\, Robert Carey\n\nAbstract:\n\nTerahertz (THz) frequencies com
	prise the portion of the electromagnetic spectrum more\nenergetic than micr
	owaves\, but less energetic than infrared light. The THz band presents\nman
	y opportunities for condensed matter physics and optics engineering. From t
	he physics\nperspective\, advances in the generation and detection of THz r
	adiation have opened the\ndoor for spectroscopic studies of a range of soli
	d-state phenomena that manifest at THz\nfrequencies. From an engineering pe
	rspective\, THz frequencies are an under-used spectral\nregion\, ripe for t
	he development of new devices. In both cases\, the challenge for researcher
	s\nis to overcome a lack of sources\, detectors\, and optics for THz light\
	, termed the THz Gap.\nMetamaterials (MMs)\, composite structures with engi
	neered index of refraction\, n\, and\nimpedance\, Z\, provide one path towa
	rds realizing THz optics. MMs are an ideal platform\nfor the design of loca
	l EM eld distributions\, and far-eld optical properties. This is espe-\ncia
	lly true at THz frequencies\, where fabrication of inclusions is easily acc
	omplished with\nphotolithography. Historically\, MM designs have been based
	 around static congurations\nof resonant inclusions that work only in a nar
	row frequency band\, limiting applications.\nBroadband and tunable MMs are 
	needed to overcome this limit.\nThis dissertation focuses on creating tunab
	le and controllable MM structures through\nthe manipulation of electromagne
	tic interactions between MM inclusions. We introduce\nthree novel MM system
	s. Each system is studied computationally with CST-Studio\, and\nexperiment
	ally via THz spectroscopy.\nFirst\, we look at the tunable transmission spe
	ctrum of two coupled split ring resonators\n(SRRs) with dierent resonant fr
	equencies. We show that introducing a lateral displacement\nbetween the two
	 component resonators lowers the electromagnetic coupling between the\nSRRs
	\, activating a new resonance.\nSecond\, we study an SRR array\, coupled to
	 a non-resonant closed ring array. We\nshow that lowering the interaction s
	trength through lateral displacement changes the MM\noscillator strength by
	  40% and electric eld enhancement by a factor of 4.\nFinally\, we show tha
	t interactions between a superconducting SRR array and a con-\nducting grou
	nd plane result in a temperature and eld strength dependent MM absorption.\
	nThe peak absorption changes by  40% with increasing electric eld and by  6
	6% with\nincreasing temperature.\n\n\n![George Keiser](/resources/event-ima
	ge/1362/8164a55_small)
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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