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<p>Intense developments in optical metamaterials have led to a renaissance in several
optics fields. Metamaterials, artificially structured media, provide several additional
degrees of freedom that cannot be accessed with conventional materials. For example,
metamaterials offer a convenient and precise way to explore a wide range of refractive
indices, including negative values. </p><p>In this dissertation, I introduce the idea
of metamaterial based diffractive optics. Merging diffractive optics with metamaterials
has several benefits, including access to almost continuous phase profiles and a wide
range of available controlled anisotropy. I demonstrate this concept with several
examples. I begin with an example of metamaterial based blazed diffraction grating
using gradient index metamaterials for <em>f</em>É = 10.6 <em>f</em>Êm. A series of
non-resonant metamaterial elements were designed and fabricated to mimic a saw-tooth
refractive index profile with a linear index variation of . The linear gradient profile
is repeated periodically to form the equivalent of a blazed grating, with the gradient
occurring across a spatial distance of 61 <em>f</em>Êm. The index gradient is confirmed
by comparing the measured magnitudes of the -1, 0 and +1 diffracted orders to those
obtained from full wave simulations. </p><p>In addition to a metamaterial grating,
a metamaterial based computer-generated phase hologram was designed by implementing
the Gerchberg-Saxton (GS) iterative algorithm to form a 2D phase panel. A three layer
metamaterial hologram was fabricated, with the size of 750 <em>f</em>Êm ~ 750 <em>f</em>Êm.
Each pixel is comprised of metamaterial elements. This simple demonstration shows
the potential for practical applications of metamaterial based diffractive optics.</p><p>The
demand for compact and integrated optoelectronic systems increases the urgency for
optical components that can simultaneously perform various functions. This dissertation
also presents an optical element capable of multiplexing two diffraction patterns
for two orthogonal linear polarizations, based on the use of non-resonant metamaterial
cross elements. The metamaterial cross elements provide unique building blocks for
engineering arbitrary birefringence. As a proof-of-concept demonstration, I present
the design and experimental characterization of a polarization multiplexed blazed
diffraction grating and a polarization multiplexed computer-generated hologram, for
the telecommunication wavelength of <em>f</em>É = 1.55 <em>f</em>Êm. A quantitative
study of the polarization multiplexed grating reveals that this approach yields a
very large polarization contrast ratio. The results show that metamaterials can form
the basis for a versatile and compact platform useful in the design of multi-functional
photonic devices. </p><p>The examples I have mentioned only provide a glimpse of the
opportunities for metamaterials. I envision more compact optical devices, with greater
functionality, being realized with metamaterials.</p>
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