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Proceedings Paper

Direct coupling of coherent emission from site-selectively grown III-V nanowire lasers into proximal silicon waveguides (Conference Presentation)
Author(s): Thomas Stettner; Tobias Kostenbader; Daniel Ruhstorfer; Jochen Bissinger; Hubert Riedl; Michael Kaniber; Gregor Koblmueller; Jonathan J. Finley

Paper Abstract

Semiconductor nanowire (NW) lasers are nanoscale coherent light sources that exhibit a small footprint, low-threshold lasing characteristics, and properties suitable for monolithic integration onto Si photonic circuits. An important milestone on the way towards novel on-chip photonic functionalities is the integration of individual, deterministically addressable NW lasers on Si waveguides with efficient coupling and mode propagation in the underlying photonic circuit. Here, we demonstrate the monolithic integration of single GaAs-based NW lasers directly onto lithographically defined Si ridge waveguides (WG). Subject to optical excitation, the observed lasing behavior shows clear “s-shape”-characteristics, linewidth narrowing and threshold values down to 19.8±1 µJ/cm², which is the lowest value reported to date for this kind of integrated lasing structure. The lasing mode of individual NW lasers is shown to couple efficiently into propagating modes of the underlying orthogonal Si WG, preserving the spectral characteristics during mode pro-pagation in the WG, and in good agreement with Finite-Difference Time-Domain (FDTD) simulations. Using a WG structure with a series of mask openings along the central mode propagation axis, we further illustrate the out-coupling properties of both spontaneous and stimulated emission and demonstrate propagation of the lasing mode over distances > 60 µm, despite absorption in the silicon dominating the propagation losses. By replacing the bulk GaAs as the active gain medium by InxGa1-xAs quantum wells, the emission wavelength can be shifted towards telecommunication bands in order to reduce the absorption losses in silicon. These results pave the way for future on-chip monolithic integration of III-V NW lasers onto silicon based optoelectronic circuits.

Paper Details

Date Published: 14 March 2018
Proc. SPIE 10538, Optical Interconnects XVIII, 1053817 (14 March 2018); doi: 10.1117/12.2288439
Show Author Affiliations
Thomas Stettner, Walter Schottky Institut (Germany)
Tobias Kostenbader, Walter Schottky Institut (Germany)
Daniel Ruhstorfer, Walter Schottky Institut (Germany)
Jochen Bissinger, Walter Schottky Institut (Germany)
Hubert Riedl, Walter Schottky Institut (Germany)
Michael Kaniber, Walter Schottky Institut (Germany)
Nanosystems Initiative Munich (Germany)
Gregor Koblmueller, Walter Schottky Institut (Germany)
Nanosystems Initiative Munich (Germany)
Jonathan J. Finley, Walter Schottky Institut (Germany)
Nanosystems Initiative Munich (Germany)

Published in SPIE Proceedings Vol. 10538:
Optical Interconnects XVIII
Henning Schröder; Ray T. Chen, Editor(s)

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