Integration of superluminescent LEDs on silicon waveguide circuits

Research Area: Heterogeneous integration technology for silicon photonics , Integrated lasers and LEDs , Silicon photonics for biomedical applications , Silicon photonics for lab-on-chip spectroscopy

Main Researcher: Andreas De Groote

Integration of superluminescent LEDs on silicon waveguide circuits
Superluminescent LEDs combine the high power and directionality of a laser and the low coherence and high bandwidth of a LED. The main gain mechanism is stimulated emission (as in a laser), but any feedback mechanism is missing (as in a LED).

Typical applications of these sources are optical coherence tomography and fiber optic gyroscopes. Optical coherence tomography is a microscopy technique which allows for micron-scale resolution and centimeter scale penetration depth. This technique is widely used to image the eye retina or cornea, but also to project the layer thicknesses of multilayer structures. In both of these applications an increased bandwidth and decreased coherence length leads to a higher resolution.
Fiber optic gyroscopes make use of the Sagnac effect, which depicts that a rotation will lead to a different path length of the clockwise and counter clockwise direction in a ring. When probing this ring with a broadband source, the rotation can be calculated for the interference of these modes. A higher bandwidth reduces the influence of scattering and reflections at facets. This is particularly important when measuring at low rotation speeds.

In this project we aim to build a superluminescent LEDs on silicon waveguides. Because the bandwidth of one type of quantum well is limited to +-80nm, we use different techniques to create different band gaps. Quantum well intermixing changes the shape of the quantum wells by a high temperature thermal anneal, causing the band gap to blueshift. Multiple die bonding makes use of the silicon waveguides as a platform to integrate different epitaxially grown layer stacks. Different InP dies are bonded to the silicon and then processed simultaneously.

Other people involved:

• Andreas De Groote

Publications

International Journals


1. 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, J. 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 doi:10.1364/PRJ.3.000B47 (2015)  .
2. A. De Groote, J.D. Peters, M.L. Davenport, M. Heck, R. Baets, G. Roelkens, J. Bowers, Heterogenously integrated III-V on silicon multi-bandgap super luminescent light emitting diode with 290nm optical bandwidth, Optics Letters, 39(16), p.4784-4787 doi:10.1364/OL.39.004784 (2014)  .