The use of parametric processes in materials presenting a third order nonlinearity is a well-known technique for the demonstration of optical signal processing functionalities, including wavelength conversion, parametric amplification, optical phase conjugation and regeneration}. Such demonstrations have traditionally been performed using highly nonlinear optical fibers (HNLFs) as the nonlinear interaction medium. However, due to their relatively weak nonlinearity, HNLF lengths of the order of several hundred meters are typically required. In such fibers, the efficiency of parametric processes is often limited by stimulated Brillouin scattering (SBS). Furthermore, longitudinal variations of the dispersion may affect the fulfillment of the phase matching condition, hence the parametric device bandwidth. Therefore, even though fiber modules can be made relatively compact, and in spite of the maturity of the HNLF technology, other nonlinear materials have been investigated over the past few years.

Optical planar waveguides made from high-index nonlinear media presenting a higher nonlinear coefficient than silica HNLFs enable compact implementations of parametric devices. In particular, nano-waveguides made from crystalline silicon have been successfully employed for all-optical signal processing. Such devices are compact, do not exhibit strong SBS, and benefit from widely tunable dispersion properties, hence flexibility in fulfillment of the phase matching condition, by engineering the cross-section of the waveguide.

(a) Microscope image of a whole polarization insensitive wavelength converter. (b) Schematic structure of a polarization splitter and rotator.

We work on the following topics:

• Wavelength conversion and phase sensitive amplification in silicon waveguides
• Phase sensitive amplification
• Signal processing using AlGaAs nanowires

Relevant NATEC papers:

L. K. Oxenlowe, M. Galili, H. C. H. Mulvad, K. Yvind, J. M. Hvam, A. T. Clausen, and P. Jeppesen, “Silicon Photonics for Signal Processing of Tbit/s Serial Data Signals”, IEEE J. Sel. Top. Quantum Electron. 18, 996–1005 (2012).

L. K. Oxenløwe, M. Galili, H. C. H. Mulvad, K. Yvind, J. M. Hvam, A. T. Clausen, and P. Jeppesen, “Silicon Photonics for Signal Processing of Tbit/s Serial Data Signals”, IEEE J. Sel. Top. Quantum Electron. 18, 996–1005 (2012).

Y. Ding, B. Huang, H. Ou, F. Da Ros, and C. Peucheret, “Polarization diversity DPSK demodulator on the silicon-on-insulator platform with simple fabrication.”, Opt. Express 21, 7828–34 (2013).

D. Vukovic, Y. Ding, H. Hu, H. Ou, L. K. Oxenløwe, and C. Peucheret, “Polarization insensitive wavelength conversion of 40 Gb/s NRZ-DPSK signal in a silicon polarization diversity circuit”, Accept. Publ. Opt. Express (2014).

F. Da Ros, D. Vukovic, A. Gajda, K. Dalgaard, L. Zimmermann, B. Tillack, M. Galili, K. Petermann, and C. Peucheret, “Phase regeneration of DPSK signals in a silicon waveguide with reverse-biased p-i-n junction.”, Opt. Express 22, 5029–36 (2014)