Adibi, Ali

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Now showing 1 - 10 of 10
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    A Temperature-Insensitive Third-Order Coupled-Resonator Filter for On-Chip Terabit/s Optical Interconnects
    (Georgia Institute of Technology, 2010-12) Li, Qing ; Yegnanarayanan, Siva ; Soltani, Mohammad ; Alipour, Payam ; Adibi, Ali
    We design and demonstrate a temperature-insensitive third-order coupled-resonator filter in the silicon-on-insulator platform for on-chip terabit/s optical interconnects. Optimum filter design enables up to 21 flat-band filter channels with more than 10 dB through-port extinction, more than 0.75-nm 3-dB bandwidth, and less than 1-dB insertion loss. By overlaying a negative thermo-optic coefficient polymer cladding on top of the silicon device, the sensitivity of the filter performance to the ambient temperature variations is significantly reduced. Moreover, through careful balancing between the dispersion of the bandwidth and the thermal property of the filter, the redundant bandwidth of filter channels due to dispersion is employed as thermal guard bands. As a result, the filter can accommodate 21 wavelength-division-multiplexing channels with data rates up to 100 Gb/s per wavelength channel while providing sufficient thermal guard bands to tolerate more than 15 C temperature fluctuations in the on-chip environment.
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    Proximity Lithography in Sub-10 Micron Circuitry for Packaging Substrate
    (Georgia Institute of Technology, 2010-11) Wang, Fengtao ; Liu, Fuhan ; Kong, Linghua ; Sundaram, Venky ; Tummala, Rao R. ; Adibi, Ali
    Rapid changes in the semiconductor industry will continue toward higher functionality that leads to higher input/outputs (I/O) counts, pushing packaging towards higher density architectures. In the next two to three years, the I/O pitch will fall within 100 μm for area array die and 30 μm for periphery die. That raises an important question to the packaging industry: How will the rapid shrinkage of the I/O pitch affect the package substrate for chip attaching? The answer is sub-10 micron copper line technology. Theoretical and experimental studies on the limitations of using mercury i-line ultraviolet photolithography have been carried at the Packaging Research Center at Georgia Tech. Furthermore, ultra fine copper line routing substrates are demonstrated for flip chip attaching by using semi-additive metallization process.
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    Detecting Early Stage Pressure Ulcer on Dark Skin Using Multispectral Imager
    (Georgia Institute of Technology, 2010) Yi, Dingrong ; Kong, Linghua ; Sprigle, Stephen ; Wang, Fengtao ; Wang, Chao ; Liu, Fuhan ; Adibi, Ali ; Tummala, Rao R.
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    A row-action based L₁-minimization approach to robust fluorescent tomography
    (Georgia Institute of Technology, 2009-10) Mohajerani, Pouyan ; Behrooz, Ali ; Eftekhar, Ali A. ; Adibi, Ali
    We present a row-action method based on minimization of the L₁ norm for improving the accuracy of fluorescent tomography in reconstruction of fluorescent objects. The method is validated using a CW system and milk-based phantoms.
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    Large-scale array of small high-Q microdisk resonators for on-chip spectral analysis
    (Georgia Institute of Technology, 2009-10) Soltani, Mohammad ; Li, Qing ; Yegnanarayanan, Siva ; Momeni, Babak ; Eftekhar, Ali Asghar ; Adibi, Ali
    We demonstrate on-chip, large-scale arrays of small high-Q microdisk resonators, suitable for both in-plane coupling and out-of-plane (imaging) spectral analysis devices with high resolution (linewidth < 50pm to 0.5nm), and large FSR (> 50nm).
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    Analysis of telescope arrays based receiver for deep-space optical communications with Mars
    (Georgia Institute of Technology, 2009-10) Hashmi, A. ; Eftekhar, Ali Asghar ; Adibi, Ali ; Amoozegar, Farid
    Telescope arrays receivers are analyzed for deep-space optical communications between Earth and Mars. It is shown that data rates up to 14 M bits/sec are possible when Mars is at the farthest range from the Earth.
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    Athermal operation in polymer-clad silicon microdisk resonators
    (Georgia Institute of Technology, 2009-10) Alipour, Payam ; Hosseini, Ehsan Shah ; Eftekhar, Ali Asghar ; Momeni, Babak ; Adibi, Ali
    We have used a urethane polymer as cladding to reduce the temperature sensitivity of resonance in high-Q silicon microdisk resonators. A two-order-of-magnitude improvement in resonance stability is demonstrated, and effects on the Q-factor are discussed.
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    Sub-microsecond thermal reconfiguration of silicon photonic devices
    (Georgia Institute of Technology, 2009-10) Atabaki, Amir H. ; Eftekhar, Ali A. ; Yegnanarayanan, Siva ; Adibi, Ali
    Using the experimental data we show the possibility of sub-microsecond reconfiguration of silicon photonics microresonators through pulse shaping of micro-heater excitation. Also, a novel heater structure based on small microdisk resonators with sub-hundred-nanosecond reconfiguration speed is proposed and investigated theoretically.
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    Sustained GHz oscillations in ultra-high Q silicon microresonators
    (Georgia Institute of Technology, 2009) Soltani, Mohammad ; Yegnanarayanan, Siva ; Li, Qing ; Atabaki, Amir ; Eftekhar, Ali A. ; Adibi, Ali
    We report the experimental observation of long-sustained GHz electronic oscillations resulting from coupled electron-photon dynamics in ultra-high-Q Si microdisk resonators with CW pumping. Theoretical analysis identifies conditions for steady-state GHz oscillations while suppressing thermal oscillations.
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    Adaptive Optics based Telescope Arrays Receiver for Compensation of Optical Turbulence Effects in a Deep-Space Optical Communication link with Mars
    (Georgia Institute of Technology, 2009) Hashmi, A. ; Eftekhar, Ali Asghar ; Adibi, Ali ; Amoozegar, Farid
    Future deep-space exploration missions demand a broadband and integrated communication infrastructure to transport the scientific data to Earth. Optical communication employing optical arrays receiver is a viable alternative to the current NASA deep-space RF-based network. Atmospheric turbulence is a major limiting factor for the inter-planetary optical links. Investigation of the use of adaptive optics subsystems is carried out for the compensation of coupled effects of optical turbulence and background noise, in direct detection optical array receivers. The simulation and analysis of an end-toend deep-space optical communication link between a spacecraft in Mars orbit and Earth-based telescope array receivers show that the incorporation of adaptive optics systems results in considerable performance improvement in achievable data rates.