Contact
Kresten Yvind, Building 345V, Room 174, 4525 3636, kryv@fotonik.dtu.dk
Minhao Pu, Building 345V, Room 175, 4525 6358, mipu@fotonik.dtu.dk
Motivation
The fast development of high-speed Internet, enabled by the modern optical fibre technologies, is changing the way people work, interact and communicate. Although the backbone network bandwidth is currently upgrading to 100 Gbit/s, it may not be enough in the near future due to dramatic increasing data traffic demand from bandwidth hungry applications like cloud computing, cloud storage, high-resolution (4K and 3-D) video streaming. For future ultra-broad bandwidth (from Terabit/s to Petabit/s) network, ultra-fast all-optical signal processing technology is also highly desired. High index contrast material platforms such as silicon-on-insulator [1] and aluminium gallium arsenide (AlGaAs) on insulator [2] provide integrated nonlinear solutions for signal processing as the optical nano-waveguides made on the material platforms offer strong sub-micron light confinement and highly engineerable dispersion property. Previously, we have demonstrated various ultra-fast signal processing applications [3] such as signal regeneration, wavelength conversion (see the figure), multicasting, demultiplexing, waveform sampling in dispersion engineered nano-waveguides. The capability of processing Terabit/s signal in just a several-millimeter long device encourages us to further explore the physical limit of the mentioned nonlinear platforms. Therefore, further optimization of performances (efficiencies, bandwidth, thermal stabilities, and tenability) for the nano-waveguide based devices is favored, and it can be the focus of the possible project. Optimization of the waveguides for sensing application, use of both χ(2) and χ(3) nonlinearities or more elaborate designs for integrated nonlinear photonics may also be the focus of the project.
Figure (a) Schematic illustration of an example optical signal processing: all-optical wavelength conversion of data signals based on degenerate four-wave mixing in a nonlinear chip. (b) SEM picture of an AlGaAsOI nano-waveguide fabricated by electron-beam lithography and inductive-coupled plasma dry etching process. (c) Photograph of a one-euro coin and a fabricated 4-mm-wide AlGaAsOI photonic chip accommodating hundreds of waveguide-based devices.
Project possibilities
In our group we do the whole process of making a functioning integrated optic chip, which includes design, fabrication, characterization and even implementation the chip in the ultra-high speed optical communication system lab (e.g our world-record high 661 Terabit/s transmission using chip-based transmitter). In a 34029 physics project your main task will be in the design using state-of-the-art simulation tools for photonics like the commercial software Lumerical will be provided for modelling the nano-waveguide properties, which is crucial for nonlinear processes. Also, basic optical characterization (e.g. loss and four-wave mixing efficiencies) of fabricated chips may be part of a project. If relevant and feasible, fabrication of your design may be done by staff and you can follow (some of) the steps done here in our state-of-the-art cleanroom facility in Danchip.
[1] J. Leuthold, C. Koos, and W. Freude, “Nonlinear silicon photonics,” Nat. Photonics, vol. 4, no. 8, pp. 535–544, Aug. 2010.
[2] M. Pu, et al., “Efficient frequency comb generation in AlGaAs-on-insulator,” Optica, vol. 3, no. 8, p. 823, Aug. 2016.
[3] L. K. Oxenlowe et al., “Silicon Photonics for Signal Processing of Tbit/s Serial Data Signals,” IEEE J. Sel. Top. Quantum Electron., vol. 18, no. 2, pp. 996–1005, Mar. 2012.
[4] J. Leuthold, C. Koos, and W. Freude, “Nonlinear silicon photonics,” Nat. Photonics, vol. 4, no. 8, pp. 535–544, Aug. 2010.
[5] M. Pu, et al., “Efficient frequency comb generation in AlGaAs-on-insulator,” Optica, vol. 3, no. 8, p. 823, Aug. 2016.
[6] L. K. Oxenlowe et al., “Silicon Photonics for Signal Processing of Tbit/s Serial Data Signals,” IEEE J. Sel. Top. Quantum Electron., vol. 18, no. 2, pp. 996–1005, Mar. 2012.