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Chi(3) telecom-wavelength nonlinear optics in silicon-based waveguide circuits

Research Area: Integrated nonlinear optics , Silicon photonics for telecom, datacom and interconnect

Main Researcher: Francois Leo

Nonlinear silicon photonics is drawing a lot of interest because of its potential applications in telecommunications and spectroscopy. Due to the intrisically high nonlinear index of silicon and the high confinement offered by the silicon-on-insulator platform, nonlinear parameters 5 orders of magnitude higher than that of standard optical fibers have been reported. However, the telecom band lies above half the band gap of silicon such that two photon absorption (TPA) is relatively high. However, due to the slow recombination time in silicon (1 ns), it is the subsequent free carrier absorption (FCA) that is really detrimental to the observation of most nonlinear effects. We are currently investigating how to circumvent this problem. The main three directions are moving to new materials, compatible with the silicon platform, remove the carriers electrically or the use of short pulses so FCA becomes negligible.

SEM cross section and color-map of the mode distribution in a silicon on insulator waveguide. From X. Liu, R. M. Osgood, Y. A. Vlasov, and W. M. J. Green, Nature Photonics 4, 557 (2010).
SEM cross section and color-map of the mode distribution in a silicon on insulator waveguide. From X. Liu, R. M. Osgood, Y. A. Vlasov, and W. M. J. Green, Nature Photonics 4, 557 (2010).

Our main focus has been on the use of hydrogenated amorphous silicon waveguides. The band gap of such waveguides was measured to be 1.6 eV (crystalline silicon has a band gap of 1.12 eV), which corresponds to a wavelength of 1550 nm for the TPA threshold. This resulted in the demonstration of 26.5 dB amplification at telecom wavelengths. However a degradation of the material under high optical powers was observed, due to the recombination of carriers (known as the Staebler-Wronski effect). However it is possible to carbon-dope the a-Si in order to increase the band gap and hence reduce the TPA. Another possibility is to move to other materials, such as large band gap III-V semiconductors that can be integrated on the silicon platform (e.g. through bonding) and possess similarly high third order nonlinearities. Working with short pulses is another way of avoiding FCA. It was predicted by simulations that supercontinuum generation through soliton fission is possible at telecom wavelength. Finally, as it is not the TPA but rather the FCA that kills the performance, it was demonstrated that CW nonlinear effects could be observed by removing carriers through the integration of a reverse biased PIN junction.

Other people involved:


Characterization of graphene-covered SiN waveguide using four-wave mixing Characterization of graphene-covered SiN waveguide using four-wave mixing

PhD thesises


    International Journals

  1. N. Poulvellarie, C. Ciret, B. Kuyken, F. Leo, S. P. Gorza, Highly Non-Degenerate Two-Photon Absorption in Silicon Wire Waveguides, Physical Review Applied, 10, p.024033  (2018).
  2. U.D. Dave, C. Ciret, S.-P. Gorza, S. Combrie, A. De Rossi, F. Raineri, G. Roelkens, B. Kuyken, Dispersive wave based octave spanning super continuum generation in InGaP membrane waveguides on a silicon substrate, Optics Letters, 40(15), p.3584 (2015)  Download this Publication (1.7MB).
  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).
  4. U.D. Dave, B. Kuyken, F. Leo, S.P. Gorza, S. Combrie, A. De Rossi, F. Raineri, G. Roelkens, Nonlinear properties of dispersion engineered InGaP photonic wire waveguides in the telecommunication wavelength range, Optics Express, 23(4), p.4650 (2015)  Download this Publication (1.1MB).
  5. F. Leo, S.P. Gorza, S.Coen, B. Kuyken, G. Roelkens, Coherent supercontinuum generation in a silicon photonic wire in the telecommunication wavelength range, Optics Letters, 40(1), p.123-126 (2015)  Download this Publication (377KB).
  6. F. Leo, J. Safioui, B. Kuyken, G. Roelkens, S.P. Gorza, Generation of coherent supercontinuum in a-Si:H waveguides: experiment and modeling based on measured dispersion profile, Optics Express, 22(23), p.28997-29007 (2014)  Download this Publication (987KB).
  7. F. Leo, S-P. Gorza, J.Safioui, P. Kockaert, S. Coen, U.D. Dave, B. Kuyken, G. Roelkens, Dispersive wave emission and supercontinuum generation in a silicon wire waveguide pumped around the 1550 nm telecommunication wavelength, Optics letters, 39(12), p.3623 (2014).
  8. J. Safioui, F. Leo, B. Kuyken, S. Selvaraja, R. Baets, P. Emplit, G. Roelkens, S. Massar, Supercontinuum generation in hydrogenated amorphous silicon waveguides at telecommunication wavelengths, Optics Express, 22(3), p.3089-3089 (2014)  Download this Publication (1.3MB).
      International Conferences

    1. K. Alexander, M. Mohsin, U.D. Dave, L. Abdollahi Shiramin, S. Clemmen, D. Neumaier, B. Kuyken, D. Van Thourhout, Electrically Tunable Optical Nonlinearity of Graphene-covered SiN waveguides, Conference on Lasers and Electro-Optics (CLEO) 2017, United States, p.paper FM2F.3 (2017)  Download this Publication (605KB).
    2. K. Alexander, B. Kuyken, D. Van Thourhout, Characterization of graphene-covered SiN waveguide using four-wave mixing, Annual Symposium of the IEEE Photonics Benelux Chapter, Belgium, (2016)  Download this Publication (178KB).
    3. U.D. Dave, B. Kuyken, Sylvain Combrie, Alfredo De Rossi, Fabrice Raineri, G. Roelkens, Octave spanning supercontinuum generation in InGaP waveguides on a silicon substrate at 1550 nm, Integrated Photonics Research, Silicon and Nano Photonics (IPR 2015), United States, p.paper IM4B.5 (2015)  Download this Publication (257KB).

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