Manufacturing Technology
EU consortium, PICMOS demonstrate a move towards full photonic interconnect layer on-chip optical interconnect.
EU consortium demonstrates Optical Interconnect Layer on Silicon
PICMOS, a European consortium of 7 partners led by IMEC/Ghent University and involving among others CEA-LETI and Lyon Nanotechnology Institute, have demonstrated what is thought to be for the first time an electrically pumped microdisk laser integrated with a nanophotonic silicon wire waveguide.
The research project has unveiled that, inP-microdisk lasers with a diameter of 7.5 µm showed a low threshold current of only 500 µA under CW operation and a side-mode-suppression ratio of 30 dB. This result forms an essential step in the effort of the consortium towards demonstrating a full photonic interconnect layer for on-chip optical interconnect.
The device was fabricated using a heterogeneous integration process consisting of a combination of a rapid die-to-wafer bonding technique and waferscale technologies compatible with CMOS fabrication processes.
The measured slope efficiency of light coupled to the 500-nm-wide silicon was 30 µW/mA. Over 100 µW was coupled to the silicon waveguide under pulsed operation. [1]. Preliminary results [2] have now also shown further integration with a microdetector, hereby the PICMOS consortium has reached its goal of demonstrating a full optical link consisting of microlaser, nanophotonic waveguide and microdetector, compatible with onchip integration. On-chip optical interconnect is seen as a possible solution for the data-transfer bottleneck on the global interconnect level in future generation ICs [3]. PICMOS demonstrated the feasibility of realising a practical interconnect layer that can be integrated with the top-level metal interconnect levels of future generation IC’s.
Intensive research in this domain is now also starting in the USA and Asia. The availability of a generic platform for electro-photonic integration could have a much broader impact however, besides the specific application investigated in PICMOS.
By combining multiple microdisk lasers with slightly different diameter with a single silicon wire waveguide, one could make very compact but very powerful transmitters, for use in both on- and off chip data links with high capacity, or, through the combination with compact WDM circuits, very high flexibility. Also for building very powerful but at the same time very cheap optical biosensors this platform could be particularly attractive.
References
[1] J. Van Campenhout, P. Rojo Romeo, P. Regreny, C. Seassal, D. Van Thourhout, S. Verstuyft, L. Di Cioccio, J. -M. Fedeli, C. Lagahe, and R. Baets, “Electrically pumped InP-based microdisk lasers integrated with a nanophotonic silicon-on-insulator waveguide circuit,” Opt. Express 15, 6744-6749 (2007) http://www.opticsinfobase.org/abstract.cfm?URI=oe-15-11-6744
[2] P.R.A. Binetti, J. Van Campenhout, X.J.M. Leijtens, M. Nikoufard, T. de Vries, Y.S. Oei, L. Di Cioccio, J.-M. Fedeli, C. Lagahe, R. Orobtchouk, X. Letartre, P. Regreny, P. Rojo Romeo, C. Seassal, P.J. van Veldhoven, R. Notzel, D. Van Thourhout, R. Baets a, ‘An Optical Interconnect Layer on Silicon’, Proc. 13th European Conference on Integrated Optics (ECIO’07) Post-deadline, Copenhagen, Denmark, 25-27 April 2007
[3] E.g. see ITRS roadmap (International Technology Roadmap for Semiconductors - http://www.itrs.com)
