Rutgers University
Electrical & Computer Engineering
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The State University of New Jersey |
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* Board-level optical interconnects based on conventional photonics * On-chip optical interconnects based on silicon photonics |
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* Low-cost, high-throughput fabrication * For photonic crystal nanostructures or large scale molding |
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Fabrication: Nanoimprint/molding, Holography |
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Optical Interconnects |
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Superprism effect & photonic crystal interface physics |
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Slot photonic crystal waveguides |
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* Publications: JAP07, APL07, APL05 * News report: Nature Photonics |
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* Publications: APL07, SSE07, JSTQE08, ... * News reports: * Nature Photonics: Research Highlights, * NASA Tech Brief, Laser Focus World, more... |
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Active Silicon Photonic Devices based on photonic crystal structures * The first 1GHz photonic crystal waveguide modulator * Scaling law for the electric current density of high-speed silicon modulators (leading to the prediction of power consumption) |
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Research Photonic crystals research had exciting development in the last two decades. Built upon many advances in physics and materials research, electrically driven photonic crystal devices such as lasers and electro-optic modulators have been demonstrated recently with orders of magnitude better performance than their conventional counterparts. Looking ahead, challenges remain in reducing slow light loss, further improving cavity quality factors, further reducing device power consumption, seeking the limit of photonic crystal dispersion (longitudinal and angular). We contributed to some of these past efforts (e.g. modulator, slot PCW, superprism, and slow light loss), and keep exploring the physics to push the limits of slow light and superprism effects. Occasionally, photonic crystal research also brought us a deeper understanding of some fundamental problems in solid state physics, such as wave transmission through the surface of a periodic lattice, and the cross-sectional eigenmode orthogonality in 1D-periodic structures with finite cross-sections (e.g. PCW or nanowire). Silicon photonics emerged in recent years with the potential for low-cost large-scale photonic-electronic integration. Silicon photonic crystal devices offer novel mechanisms to improve the performance of conventional silicon photonic devices as demonstrated in our prior work (e.g. modulator, slot PCW). Furthermore, these efforts also brought us fundamental understanding of current density scaling and power consumption of Si electro-optic devices, and led us to new directions such as quadrature amplitude modulation. When the low-cost large-scale monolithic integration capability of silicon photonics meets the intriguing physics of slow light and superprism in photonic crystals, an area of abundant opportunities is unfolding. To explore these opportunities we need innovative ideas, practical rationale, physical insight, efficient simulation/modeling, and careful fabrication. You are welcome to browse through our work on this website, and uncover new paths in this promising land. |
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Slow light loss in a photonic crystal waveguide * Analytic theory reveals general characteristics of slow light loss * Loss coefficient a=a1ng+a2ng2 (ng group index) * a1 and a2 are analytically shown comparable in magnitude * Interplay between the spatial phase of PCW mode and the roughness-correlation is critical * Agree well with experiment * Surprising byproduct: cross-sectional eigenmode orthogonality |
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Dual racetrack Si micro-resonators for quadrature amplitude modulation * Strong coherent cross-coupling between two parallel racetrack micro-resonators * In over-coupling scenario, there is a delicate balance between the direct sum and “interactions” of two resonances * Large amplitude & phase modulation ranges * Suitable for arbitrary quadrature amplitude modulation (including DPSK, QPSK, 16-QAM, etc.) * Resilient against fabrication imperfections * Publications: OE11. * Provisional Patent filed. |
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Slow light Thermo-optic Switches * Power consumption and spatial temperature profile are found as explicit functions of structural, thermal and optical parameters * Agree with FEM simulations and experiments * Air-bridge (membrane) configuration is shown to enhance the temperature rise compared to the SOI structure. * Scaling of power consumption with key parameters (buried oxide layer thickness, heater location & width, group index, etc.) * Practical analysis of slow light loss in photonic crystal waveguide switches * Sub-milliwatt switching power is possible * Publications: OE2012. |
