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Scholarly Interest Report
Qianfan Xu
Assistant Professor
Assistant Professor in Electrical and Computer Engineering
  • B.E. Electronic Engineering (1999) Tsinghua University, Beijing
  • M.E. Electronic Engineering (2002) Tsinghua University, Beijing
  • M.S. Electrical and Computer Engineering (2006) Cornell University, Ithaca, NY
  • Ph.D. Electrical and Computer Engineering (2007) Cornell University, Ithaca, NY
Department Affiliations
  • Department of Electrical and Computer Engineering
     Group Homepage
    Research Areas
     Nanophotonic Devices and Systems; Optical Interconnections; Optical Sensing; THz switches; Mid-infrared optical devices; Graphene plasmonics.
    Optoelectronic integration on chip
      The field of optics is entering a new era, with the recently acquired capability of large-scale photonic integration on chip. Thanks to the development in silicon nanophotonics and plasmonics in the last few years, the size of integrated optical devices has shrunk several orders of magnitude to the sub-micron and nanometer regime, and monolithic integration with electronic circuits has been demonstrated. These technologies will bring a complete revolution to the field of optics, like what IC technologies have brought to electronics. In the next decade or two, we can expect to see monolithically integrated optoelectronic systems with much expanded functionality and improved performance unmatched by the current purely electronic ICs.
    The most promising platform for optoelectronic integration is the one based on silicon nanophotonics, as it takes advantages of both the mature fabrication technology for microelectronics and the capability of high optical confinement in silicon. In the last few years, various photonic devices have been developed on silicon or silicon-compatible materials, including lasers, optical amplifiers, modulators, and detectors, which enable monolithic integration of a complete electro-optical system on-chip. However, many of these demonstrated devices have rather large dimensions (in millimeters), while large-scale photonic integrations require devices with small size and low power consumption.
    My research group focuses on ultra-compact optical devices on chip, including devices based on microring resonator, photonic crystal cavities, and plasmonic nanostructures. Their small size, low power consumption and strong enhancement of photon-material interaction are critical for most applications of photonics. Large-scale integration of such devices will enable high-impact applications like optical interconnection system, optical biosensing, optical imaging and optoelectronic signal processing.
    Teaching Areas
     Optics; Optoelectronics; Photonic Devices; Semiconductor Devices; Applied Quantum Mechanics
    Selected Publications
     Refereed articles

    C. Qiu and Q. Xu, “Controlling normal incident optical waves with an integrated resonator,” Opt. Express, vol. 19, 26905–26910 (2011).


    C. Qiu, J. Shu, Z. Li, X. Zhang, and Q. Xu, "Wavelength tracking with thermally controlled silicon resonators," Opt. Express, vol. 19, 5143-5148 (2011).


    J. Shu, C. Qiu, V. Astley, D. Nickel, D. M. Mittleman and Q. Xu, "High-contrast terahertz modulator based on extraordinary transmission through a ring aperture,” Opt. Express, vol. 19, 26666–26671 (2011).


    J. Shu, C. Qiu, X. Zhang, and Q. Xu, "Efficient coupler between chip-level and board-level optical waveguides," Opt. Lett. vol. 36, 3614-3616 (2011)


    Q. Xu and R. Soref, "Reconfigurable optical directed-logic circuits using microresonator-based optical switches," Opt. Express, vol. 19, 5244-5259 (2011).


    Y. Tian, L. Zhang, R. Ji, L. Yang, and Q. Xu, "Demonstration of a directed optical encoder using microring-resonator-based optical switches," Opt. Lett. vol. 36, 3795-3797 (2011).


    J. Ahn, M. Fiorentino, R.G. Beausoleil, N. Binkert, A. Davis, D. Fattal, N.P. Jouppi, M. McLaren, C.M. Santori, R.S. Schreiber, S.M. Spillane, D. Vantrease, Q. Xu, "Devices and architectures for photonic chip-scale integration," Appl. Phys. A: Materials Science & Processing vol. 95, pp. 989-997 (2009).


    P. Dong, L. Chen, Q. Xu, and M. Lipson, "On-chip generation of high-intensity short optical pulses using dynamic microcavities," Opt. Lett. vol. 34, pp. 2315-2317 (2009).


      Q, Xu, "Silicon dual-ring modulator," Opt. Express vol. 17, pp. 20783-20793 (2009).

     Q. Xu, D. Fattal, and R. G. Beausoleil, "Silicon microring resonators with 1.5-um radius", Opt. Express 16, 4309-4315 (2008)
     Sasikanth Manipatruni, Carl B. Poitras, Qianfan Xu, and Michal Lipson, "High-speed electro-optic control of the optical quality factor of a silicon microcavity," Opt. Lett. 33, 1644-1646 (2008)
     Sasikanth Manipatruni, Po Dong, Qianfan Xu, and Michal Lipson, "Tunable superluminal propagation on a silicon microchip," Opt. Lett. 33, 2928-2930 (2008)
     Book chapters

    "Microresonators with active tuning" in Photonic Microresonator Research and Applications, Springer, ISBN: 978-1-4419-1743-0

     Invited Talks

    Q. Xu and R. Soref  “Reconfigurable Electro-optical logic in silicon photonic integrated circuits,” IEEE Group IV Photonics (GFP), London, UK, 2011.


    "Compact optoelectronic devices on silicon." Prof. Jinzhong Yu, Institute of Semiconductors, Chinese Academy of Sciences, Beijing. (12/17/2008)


    "Silicon Nanophotonics." Lockheed Martin Advanced Nanotechnology Center of Excellence (LANCER) Short Courses, Rice University. (10/15/2008)


    "Silicon Nanophotonics." Prof. Yidong Huang, Tsinghua University, Beijing. (12/17/08)


    Q. Xu and R. Soref, “Reconfigurable optical directed-logic circuits using resonant silicon nano-photonic switches,” E-MRS Spring Meeting, Nice, France, 2011


     J. Shu, C. Qiu, V. Astley, D. Nickel, D. M. Mittleman and Q. Xu, “Resonant Transmission of Ring Aperture for Switching Terahertz Waves,” CLEO, Baltimore MD, 2011


    C, Qiu and Q. Xu, “Wavelength Tracking with Thermally Controlled Silicon Resonators,” CLEO Baltimore MD, 2011


    J. Shu and Q. Xu, "Efficient Coupler between Silicon and Polymer Waveguides," CMS6, Conference on Lasers and Electro-Optics(CLEO), San Jose CA, 2010.


     Q. Xu, "Silicon Modulator Based on Coupled Microring Resonators," IWA3, Integrated Photonics Research, Silicon and Nano Photonics (IPR), Monterey CA, 2010.


    Q. Xu, D. Fattal, and R. G. Beausoleil, “Ultra-compact silicon microring resonator,” 7218-38, SPIE Photonics West, San Jose CA, 2009.

     Seminar Speaker

    "Silicon Micro-Ring Modulators for Large-Scale Optical Interconnections." ECE Seminar / Hui Wu, Rochester University. (09/16/09)


    "Toward Large-scale Optoelectronic Integration on Silicon." ECE Affiliates Day, Rice University. (10/15/2008)

     Session Chair

    "Slot and High Confinement Waveguides." CLEO/IQEC, San Jose, CA. (5/8/2008)


    Q. Xu, "Silicon Micro-ring Modulators for Large-scale Optical Interconnections,” Huang Kun Semiconductor Forum, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, Aug. 30 2010.

    Editorial Positions
     Editor for Special Issue, ACM Journal on Emerging Technologies in Computing Systems,. (2011 - 2011)

    Supervised Theses & Dissertations
     Natali de Escobar Martinez, Ph. D. Bose-Einstein Condensation of 84-Sr. (2010) (Thesis Committee Member)

     Yang Lu, Ph. D. In Situ Quantitative Mechanical Characterization and Integration of One Dimensional Metallic Nanostructures. (2010) (Thesis Committee Member)

     Quang Nguyen, M. S. Water-phase Synthesis of Cationic Silica/polyamine Nanoparticles. (2011) (Thesis Committee Member)

     Jose Castro, Ph. D. Collective effects in Ultracold Neutral Plasmas. (2011) (Thesis Committee Member)

    Positions Held
     Houston Chapter Chair, IEEE Photonics Society. (2009 - 2009)