93 research outputs found
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Polymer-based integrated photonic devices for interconnects
Integrated photonic devices based on optical waveguides have been extensively studied for various applications, especially the high-speed intra- and inter-chip interconnects. Usually, a waveguide contains a core with high refractive index and cladding with lower refractive index. Among various waveguides, silicon, polymer, and silicon-polymer hybrid devices are the most promising candidates for low cost, small size, light weight, and low power consumption (CSWaP) optical interconnect. Firstly, silicon-based optical devices can be fabricated using CMOS compatible nanofabrication technology, which is already widely used to manufacture integrated circuits. Silicon photonic devices can have very small footprint and enable high density photonic circuits, due to high refractive index contrast. However, one of the intrinsic obstacles is the absence of χ⁽²⁾-nonlinearity in unstrained silicon due to its centrosymmetric crystal structure, making modulating photons on silicon platform a great challenge. Secondly, polymer-based devices have been found very attractive, owing to the advantages of high thermo-optic (TO) or electro-optic (EO) coefficient, high transparency in the telecommunication wavelength windows, and fabrication feasibility over large areas on printed circuit board (PCB) or other kinds of substrates. The roll-to-roll (R2R) compatible imprinting and ink-jet printing for developing polymer-based devices on flexible or rigid substrates enable large-area, light-weight, low-cost optical interconnects. However, due to the low refractive index contrast, the polymer photonic devices always require large footprint. Finally, the silicon-organic hybrid (SOH) platform enables the marriage of the best of these two materials and thus has been receiving substantial attention.
In this dissertation, integrated photonic devices based on silicon, polymer, or hybrid platform will be presented. First, high-efficiency quasi-vertical tapers for polymer waveguide based inter-board optical interconnects will be demonstrated. A triangular-shape tapered structure is adopted above the waveguide core to transform a fiber mode into a single mode polymer rib waveguide mode as an optical mode transformer. A coupling loss of 1.79±0.30 dB and 2.23±0.31 dB per coupler for the quasi-TM and quasi-TE mode respectively have been experimentally demonstrated, across the C and L bands (1535 nm – 1610 nm). Then, a reconfigurable thermo-optic polymer switch based true-time-delay network will be analyzed and demonstrated. Thirdly, I will show a novel subwavelength-grating waveguide ring resonator based high-speed modulators, which is the largest bandwidth and the most compact footprint that has been demonstrated for the ring resonators on the silicon-organic hybrid (SOH) platform. Finally, the on-chip time-division multiplexing and de-multiplexing system will be designed and analyzed.Electrical and Computer Engineerin
Broadband energy-efficient optical modulation by hybrid integration of silicon nanophotonics and organic electro-optic polymer
Silicon-organic hybrid integrated devices have emerging applications ranging
from high-speed optical interconnects to photonic electromagnetic-field
sensors. Silicon slot photonic crystal waveguides (PCWs) filled with
electro-optic (EO) polymers combine the slow-light effect in PCWs with the high
polarizability of EO polymers, which promises the realization of
high-performance optical modulators. In this paper, a broadband,
power-efficient, low-dispersion, and compact optical modulator based on an EO
polymer filled silicon slot PCW is presented. A small voltage-length product of
V{\pi}*L=0.282Vmm is achieved, corresponding to an unprecedented record-high
effective in-device EO coefficient (r33) of 1230pm/V. Assisted by a backside
gate voltage, the modulation response up to 50GHz is observed, with a 3-dB
bandwidth of 15GHz, and the estimated energy consumption is 94.4fJ/bit at
10Gbit/s. Furthermore, lattice-shifted PCWs are utilized to enhance the optical
bandwidth by a factor of ~10X over other modulators based on
non-band-engineered PCWs and ring-resonators.Comment: 12 pages, 4 figures, SPIE Photonics West Conference 201
Guided Surface Plasmon Mode of Semicircular Cross Section Silver Nanoridges
Tightly confined plasmon waveguide modes supported by semicircular cross
section top silver nanoridges are investigated in this paper. Mode field
profiles, dispersion curves, propagation distances, confinement factors, and
figure-of-merits of semicircular top silver nanoridge plasmon waveguide mode
are calculated for different radii of curvature at different wavelengths. It is
found that semicircular top silver nanoridges support tightly confined
quasi-TEM plasmon waveguide modes. Semicircular top silver nanoridge mode has
longer propagation distance and higher figure-of-merit than that of the
cylindrical silver nanowire of the same radius of curvature.Comment: 21 pages, 11 figure
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