Research overview
The over-arching theme of the Knights research program remains the development of highly integrated silicon photonic devices and systems, primarily for applications in high-bandwidth data-communications. This approach uses innovative materials research to provide solutions to performance limitations, ultimately exploited through device design, fabrication and characterization. The work is set within the boundary conditions of potential deployment and commercial exploitation.
The Knights group has demonstrated excellent progress using this approach.
The Knights group has demonstrated excellent progress using this approach.
Photonic DevicesProfessor Knights has worked in silicon photonics since 1996. The highest profile work in recent years has been the development of a high-speed, monolithic detector compatible with silicon photonic systems operating at a wavelength of ~2000nm. Read more.
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FacilitiesThe Knights group has a well-equipped optical laboratory for the measurement of integrated devices. The group also has access to the McMaster Centre for Emerging Device Technologies (CEDT) and the Brockhouse Institute for Materials Research (BIMR). Read more.
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CollaborationsThe Knights group collaborates with leading academic and industrial research groups in Canada, the US and Europe. Such colloboration enables technology sharing and provides opportunities for graduate students to undertake placements in leading labs. Read more.
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Research Highlights
The highest profile work in recent years has been the development of a high-speed, monolithic detector compatible with silicon photonic systems operating at a wavelength of ~2000nm. No CMOS compatible solution to integrated detection at this wavelength existed to that point, and given the emerging importance of mid-IR photonics our result was suitable for publication in Nature Photonics [1]. It received coverage in the popular science press, including an interview in Physics World. The work built on my position of leadership in defect-mediated detection which began in 2005 [2].
We continue to strive to understand the complex interaction of deep-level defects and dopants with propagating light signals in silicon waveguides. Three recent and significant results stand-out as examples.
The development of high-bandwidth transceivers remains the most important challenge for the silicon photonics community. Our recent contributions address modulator stabilization through an elegant feedback design, work in collaboration with Columbia University [6], which has resulted in a published patent, licensed by industrial partners. We also have contributed to the understanding of dispersion compensation in optical links up to 100km using silicon micro-ring modulators [7].
[1] J. J. Ackert et al., “High-speed detection at two micrometres with monolithic silicon photodiodes,” Nat. Photonics, vol. 9, no. 6, pp. 393–396, May 2015.
[2] J. D. B. Bradley, P. E. Jessop, and A. P. Knights, “Silicon waveguide-integrated optical power monitor with enhanced sensitivity at 1550 nm,” Appl. Phys. Lett., vol. 86, no. 24, p. 241103, 2005.
[3] M. Couillard, G. Radtke, A. P. Knights, and G. A. Botton, “Three-Dimensional Atomic Structure of Metastable Nanoclusters in Doped Semiconductors,” Phys. Rev. Lett., vol. 107, no. 18, p. 186104, Oct. 2011.
[4] K. J. Dudeck, L. A. Marqués, A. P. Knights, R. M. Gwilliam, and G. A. Botton, “Sub-ångstrom Experimental Validation of Molecular Dynamics for Predictive Modeling of Extended Defect Structures in Si,” Phys. Rev. Lett., vol. 110, no. 16, p. 166102, Apr. 2013.
[5] C. J. Edwardson, P. G. Coleman, D. J. Paez, J. K. Doylend, and A. P. Knights, “Direct Observation of Electron Capture and Reemission by the Divacancy via Charge Transient Positron Spectroscopy,” Phys. Rev. Lett., vol. 110, no. 13, p. 136401, Mar. 2013.
[6] K. Padmaraju, D. F. Logan, X. Zhu, J. J. Ackert, A. P. Knights, and K. Bergman, “Integrated thermal stabilization of a microring modulator,” Opt. Express, vol. 21, no. 12, p. 14342, Jun. 2013.
[7] Z. Wang, Y. Gao, A. S. Kashi, J. C. Cartledge, and A. P. Knights, “Silicon Microring Modulator for Dispersion Uncompensated Transmission Applications,” J. Light. Technol., vol. 34, no. 16, pp. 3675–3681, Aug. 2016.
We continue to strive to understand the complex interaction of deep-level defects and dopants with propagating light signals in silicon waveguides. Three recent and significant results stand-out as examples.
- Using our unique universal ion implantation system we have developed recipes for implantation of all technologically important rare-earths. We have directly observed cerium implantation profiles, and the tracking of cerium clustering, work which shed new light on rare-earth evolution in silicon [3].
- We have provided the highest resolution images and modelled the formation and dissolution of the technologically important <311> defect, which we plan to exploit in coming detector work [4].
- We have developed a new positron based characterization technique for defects, named Positron-DLTS, which will be used in the current proposal to provide new insights into defect kinetics [5].
The development of high-bandwidth transceivers remains the most important challenge for the silicon photonics community. Our recent contributions address modulator stabilization through an elegant feedback design, work in collaboration with Columbia University [6], which has resulted in a published patent, licensed by industrial partners. We also have contributed to the understanding of dispersion compensation in optical links up to 100km using silicon micro-ring modulators [7].
[1] J. J. Ackert et al., “High-speed detection at two micrometres with monolithic silicon photodiodes,” Nat. Photonics, vol. 9, no. 6, pp. 393–396, May 2015.
[2] J. D. B. Bradley, P. E. Jessop, and A. P. Knights, “Silicon waveguide-integrated optical power monitor with enhanced sensitivity at 1550 nm,” Appl. Phys. Lett., vol. 86, no. 24, p. 241103, 2005.
[3] M. Couillard, G. Radtke, A. P. Knights, and G. A. Botton, “Three-Dimensional Atomic Structure of Metastable Nanoclusters in Doped Semiconductors,” Phys. Rev. Lett., vol. 107, no. 18, p. 186104, Oct. 2011.
[4] K. J. Dudeck, L. A. Marqués, A. P. Knights, R. M. Gwilliam, and G. A. Botton, “Sub-ångstrom Experimental Validation of Molecular Dynamics for Predictive Modeling of Extended Defect Structures in Si,” Phys. Rev. Lett., vol. 110, no. 16, p. 166102, Apr. 2013.
[5] C. J. Edwardson, P. G. Coleman, D. J. Paez, J. K. Doylend, and A. P. Knights, “Direct Observation of Electron Capture and Reemission by the Divacancy via Charge Transient Positron Spectroscopy,” Phys. Rev. Lett., vol. 110, no. 13, p. 136401, Mar. 2013.
[6] K. Padmaraju, D. F. Logan, X. Zhu, J. J. Ackert, A. P. Knights, and K. Bergman, “Integrated thermal stabilization of a microring modulator,” Opt. Express, vol. 21, no. 12, p. 14342, Jun. 2013.
[7] Z. Wang, Y. Gao, A. S. Kashi, J. C. Cartledge, and A. P. Knights, “Silicon Microring Modulator for Dispersion Uncompensated Transmission Applications,” J. Light. Technol., vol. 34, no. 16, pp. 3675–3681, Aug. 2016.
Facilities
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McMaster University has a long track record in both Optoelectronics and Materials Science research. As such, the University is home to multi-user facilities which allow cutting-edge fabrication and characterization. In addition, the Knights group has a well-equipped optical laboratory for the measurement of integrated devices. Graduate students working in our group are thus guaranteed experience in the most advanced experimental techniques.
Prof. Knights is an active member of the McMaster Centre for Emerging Device Technologies (CEDT) and the Brockhouse Institute for Materials Research (BIMR). These centres support world-class device fabrication (lithography, ion implantation, metal and dielectric deposition, annealing etc.) and materials analysis (TEM, FIB-SEM, Positron Annihilation, Hall Effect, DLTS, X-Ray analysis, etc.). |
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Collaborations
The global semiconductor industry generates >$300 billion each year. There thus exists a large number of industrial and academic research groups addressing a complete range of research topics to support future deployment. For academic groups to compete in this landscape research in silicon material and devices requires a collaborative approach resulting in shared infrastructure. Using this model within the Canadian system we have been able to utilize equipment and expertise well-beyond the resources we might reasonably expect in isolation. Thus, almost all of our work is collaborative.
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In Canada we work with academic groups at Queen’s University (high-speed optical testing), UBC (integrated silicon photonics), National Research Council, Ottawa (active sub-wavelength gratings) and Western University (defect characterization). We are a long-time member and promoter of Canadian facilitator CMC Microsystems whose financial and logistical support allow us to compete with the very best groups. Internationally we collaborate with Profs R Osgood and K Bergman of Columbia University on silicon modulator control, Prof M P Halsall and Dr I Crowe of the University of Manchester on the development of optical sources, and Prof G Reed of the University of Southampton on silicon photonic device design for 2000nm.
Our primary industrial partner is Ranovus Inc who collaborate on device development and exploit research from our group with associated benefits for Canada. We also have collaborations with Canadian companies Applied Nano-Tools (ANT) (infrastructure development), Raytheon-Elcan (thin film coating wear resistance) and IntlVac (doped dielectric deposition). In 2015 we began a collaboration with the major US semiconductor company Applied Materials (AMAT) on Ge doping of silicon for strain engineering. All of these industrial partners take part in the hosting of interns from my group. |
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