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Chi(2) nonlinear optics in silicon-based waveguide circuits

Research Area: Integrated nonlinear optics , Mid IR silicon photonics , Silicon photonics for lab-on-chip spectroscopy

Main Researcher: Utsav Dave

High index contrast platforms like the silicon-on-insulator (SOI) platform offer several advantages in realizing nonlinear optical functionalities such has high nonlinearities and tight confinement resulting in large intensities. Silicon in particular has a high third order nonlinearity which has been exploited for parametric gain, supercontinuum generation etc. However, silicon possesses centrosymmetry, which means there is no bulk second order susceptibility and thus processes like difference-frequency (see figure below) and sum-frequency generation are not usually possible. Such process can offer interesting functionalities such as generation of mid-infrared radiation using the available high power lasers in the near infrared. Integrating functionalities on an on-chip platform would make it possible to lower the cost and make systems more robust for many such applications. Thus it is interesting to seek out a way to have second order nonlinear processes on silicon-based waveguide circuits.

Difference-frequency genetation
Difference-frequency genetation

There are several ways of getting around this problem to have second order nonlinearity on a silicon-based platform. Integrating materials with high second order nonlinearity on to the SOI platform such as III-V semiconductors is one such approach. Light can be coupled in to the patterned III-V membrane bonded on top of the silicon-based waveguide circuit for nonlinear interactions and the output can then be coupled back to the circuit. Another approach is to induce an inhomogeneous strain in the silicon waveguides (see figure below) by appropriately depositing a cladding layer and thus breaking the symmetry. This could allow silicon waveguides on the SOI platform to have high effective second order susceptibility. Research on these fronts is ongoing.

Strained silicon for second order susceptibility
Strained silicon for second order susceptibility

Other people involved:

PhD thesises


    International Journals

  1. A. Hermans, C. Kieninger, K. Koskinen, A. Wickberg, E. Solano, J. Dendooven, M. Kauranen, S. Clemmen, M. Wegener, C. Koos, R. Baets, On the determination of chi(2) in thin films: a comparison of one-beam second-harmonic generation measurement methodologies, Scientific Reports, 7, p.44581 (2017)  Download this Publication (948KB).
  2. S. Clemmen, A. Hermans, E. Solano, J. Dendooven, K. Koskinen, M. Kauranen, E. Brainis, C. Detavernier, R. Baets, Atomic layer deposited second order nonlinear optical metamaterial for back-end integration with CMOS-compatible nanophotonic circuitry, Optics Letters, 40(22), p.5371 (2015).
  3. A. Subramanian, E.M.P. Ryckeboer, A. Dhakal, F. Peyskens, A. Malik, B. Kuyken, H. Zhao, S. Pathak, A. Ruocco, A. De Groote, P.C. Wuytens, D. Martens, F. Leo, W. Xie, U.D. Dave, M. Muneeb, Pol Van Dorpe, Joris Van Campenhout, W. Bogaerts, P. Bienstman, N. Le Thomas, D. Van Thourhout, Zeger Hens, G. Roelkens, R. Baets, Silicon and silicon nitride photonic circuits for spectroscopic sensing on-a-chip , Photonics Research (invited), 5(3), p.B47 (2015)  Download this Publication (1.5MB).
      International Conferences

    1. A. Hermans, M. Van Daele, C. Kieninger, J. Dendooven, S. Clemmen, C. Detavernier, C. Koos, R. Baets, CMOS-Compatible ALD Zinc Oxide Coating for On-Chip Second-Order Nonlinear Optical Functionalities, Conference on Lasers and Electro-Optics 2017, United States, p.SM3K.3  (2017)  Download this Publication (373KB).
    2. A. Hermans, M. Van Daele, J. Dendooven, S. Clemmen, C. Detavernier, R. Baets, Electro-Optic Modulation in Silicon Nitride Photonic Integrated Circuits by means of ALD ZnO Overlays, European Conference on Integrated Optics (ECIO), Netherlands, p.T5.3 (2017)  Download this Publication (579KB).
    3. A. Hermans, S. Clemmen, E. Solano, J. Dendooven, E. Brainis, C. Detavernier, R. Baets, Second-harmonic generation based on symmetry breaking in a periodically layered medium, Proceedings of the 18th Annual Workshop of the IEEE/Photonics Benelux Chapter, Belgium, p.6-7 (2015).

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