This document describes an electrically pumped hybrid laser combining AlGaInAs quantum wells and a silicon waveguide. The structure overlaps the optical mode 75% with the silicon waveguide and 3% with the quantum wells. Experiments showed lasing up to 40°C with a 1.8mW output power and 65mA threshold current. Improvements like reducing thermal resistance could allow reaching the 70°C requirement for commercial applications. This hybrid integration of a III-V laser with a silicon waveguide could enable photonic integrated circuits with multiple electrically driven lasers on a silicon chip.

1. Electrically pumped
hybrid AlGaInAs-silicon evanescent laser
Jehona Salaj
University of Eastern Finland
Department of Physics and Mathematics
November 13, 2012
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

2. Hybrid integration
III-V lasers coupled to silicon waveguides.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

3. Hybrid integration
III-V lasers coupled to silicon waveguides.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

4. Outline
1 Introduction
2 Structure
3 Experiments and results
4 Conclusion
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

5. Outline
1 Introduction
2 Structure
3 Experiments and results
4 Conclusion
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

6. Introduction
Previous approaches
Raman lasers
Raman amplifiers
nano-patterning
nanocrystalline-Si structures
doping silicon rich oxides with rare earths
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

7. Introduction
Previous approaches
Raman lasers
Raman amplifiers
nano-patterning
nanocrystalline-Si structures
doping silicon rich oxides with rare earths
Limitations
Optical pumping
Work at cryogenic temperatures
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

8. Introduction
Previous approaches
Raman lasers
Raman amplifiers
nano-patterning
nanocrystalline-Si structures
doping silicon rich oxides with rare earths
Limitations
Optical pumping
Work at cryogenic temperatures
Solution
Electrically pumped hybrid AlGaInAs-silicon laser - waveguide
structure which works at temperatures up to 40◦ C
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

9. Outline
1 Introduction
2 Structure
3 Experiments and results
4 Conclusion
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

10. Structure
Figure : Schematic drawing of the structure of the laser. Optical mode
superimposed.
Optical mode overlaps 75% with the silicon waveguides and 3%
with the quantum wells.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

11. Structure
Figure : Electron microscope image of the cross section of a fabricated
hybrid AlGaInAs-silicon evanescent laser.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

12. New possibilities
Figure : Schematic drawing of an integrated silicon transmitter photonic
chip with multiple electrically driven lasers operating simultaneously, all
fabricated with a single bonding step. They are all self aligned to silicon
modulators and then all combined together with a silicon multiplexer.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

13. Outline
1 Introduction
2 Structure
3 Experiments and results
4 Conclusion
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

14. Parameters
Figure : The output power for one side coupling with a fiber plotted
against current for different temperatures.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

15. Parameters
laser threshold 65mA
maximum output power 1.8mW
maximum lasing temperature 40◦ C
waveguide-fiber coupling loss 6dB
differential quantum efficiency 12.7%
threshold voltage 2V
series resistance 7.5Ω
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

16. Spectrum
Figure : Spectrum of the laser above the threshold.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

17. Limitations
Poor heat extraction from the active region
Heat generation by the high electrical series resistance of the
thin n-layer
Possible improvements
Reduction of the buried oxide thickness to lower the thermal
resistance
Narrowing the n-contact distance from the center of
waveguide to reduce electrical series resistance
Deposition of high reflection coatings onto the waveguide
facets to reduce the threshold current
These improvements should make it possible to reach the 70◦ C
requirements of commercial transmitters.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

18. Figure : Infrared image of 7 lasers operating simultaneously taken from
one of the facets.
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser

19. Outline
1 Introduction
2 Structure
3 Experiments and results
4 Conclusion
Jehona Salaj Electrically pumped hybrid AlGaInAs-silicon evanescent laser