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Center for Organic Photonics and Electronics

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Now showing 1 - 10 of 16

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.
Multipath Fading Measurements at 5.8 GHz for Backscatter Tags With Multiple Antennas

(Georgia Institute of Technology, 2010-11) Griffin, Joshua D. ; Durgin, Gregory D.

Multipath fading can be heavy for ultra-high frequency (UHF) and microwave backscatter radio systems used in applications such as radio frequency identification (RFID). This paper presents measurements of fading on the modulated signal backscattered from a transponder for backscatter radio systems that use multiple antennas at the interrogator and transponder. Measurements were performed at 5.8 GHz and estimates of the backscatter channel envelope distributions and fade margins were calculated. Results show that multipath fading can be reduced using multiple transponder antennas, bistatic interrogators with widely separated transmitter and receiver antennas, and conventional diversity combining at the interrogator receiver. The measured envelope distribution estimates are compared to previously derived distributions and show good agreement.
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.
The Evolution Study Of Thin Film Structure During The Film Formation

(Georgia Institute of Technology, 2010-01) Park, Min Sang ; Aiyar, Avisheck ; Park, Jung Ok ; Reichmanis, Elsa ; Srinivasarao, Mohan
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.
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).
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.
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.
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.
Revisiting the Spread Spectrum Sliding Correlator: Why Filtering Matters

(Georgia Institute of Technology, 2009-07) Pirkl, Ryan J. ; Durgin, Gregory D.

A wireless channel sounder based upon the conventional spread spectrum sliding correlator implementation uses unfiltered pseudo-random noise (PN) at both the transmitter and receiver to generate a time-dilated copy of the channel’s impulse response. However, in addition to this desired impulse response, the sliding correlator also produces a noise-like, wideband distortion signal that decreases the measurement system’s dynamic range. Careful selection of the sliding correlator’s lowpass filter can significantly reduce this distortion, but no amount of filtering will remove it completely. In contrast, using filtered PNs at both the transmitter and receiver enables one to remove this distortion in entirety and realize a measurement system whose dynamic range closely approximates the theoretical ideal for spread spectrum systems.