Harnessing mode-selective nonlinear optics for on-chip multi-channel all-optical signal processing Ming Ma and Lawrence R Chen Citation: APL Photonics 1, 086104 (2016); doi: 10.1063/1.4967205 View online: http://dx.doi.org/10.1063/1.4967205 View Table of Contents: http://aip.scitation.org/toc/app/1/8 Published by the American Institute of Physics Articles you may be interested in Invited Article: Electrically tunable silicon-based on-chip microdisk resonator for integrated microwave photonic applications APL Photonics 1, 080801080801 (2016); 10.1063/1.4961685 Hybrid waveguide-bulk multi-path interferometer with switchable amplitude and phase APL Photonics 1, 081302081302 (2016); 10.1063/1.4960204 160 Gbit/s photonics wireless transmission in the 300-500 GHz band APL Photonics 1, 081301081301 (2016); 10.1063/1.4960136 Sub-megahertz linewidth single photon source APL Photonics 1, 096101096101 (2016); 10.1063/1.4966915 APL PHOTONICS 1, 086104 (2016) Harnessing mode-selective nonlinear optics for on-chip multi-channel all-optical signal processing Ming Ma and Lawrence R Chen Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montr´eal, Qu´ebec H3A 0E9, Canada (Received 13 September 2016; accepted 24 October 2016; published online November 2016) All-optical signal processing based on nonlinear optical effects allows for the realization of important functions in telecommunications including wavelength conversion, optical multiplexing/demultiplexing, Fourier transformation, and regeneration, amongst others, on ultrafast time scales to support high data rate transmission In integrated photonic subsystems, the majority of all-optical signal processing systems demonstrated to date typically process only a single channel at a time or perform a single processing function, which imposes a serious limitation on the functionality of integrated solutions Here, we demonstrate how nonlinear optical effects can be harnessed in a mode-selective manner to perform simultaneous multi-channel (two) and multi-functional optical signal processing (i.e., regenerative wavelength conversion) in an integrated silicon photonic device This approach, which can be scaled to a higher number of channels, opens up a new degree of freedom for performing a broad range of multi-channel nonlinear optical signal processing functions using a single integrated photonic device © 2016 Author(s) All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/) [http://dx.doi.org/10.1063/1.4967205] All-optical signal processing, which can take advantage of ultrafast nonlinear effects such as self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM), has potential applications in optical communications as it enables functions such as pulse shaping/waveform generation, wavelength conversion, optical (de-)multiplexing, Fourier transformation, true-time delay, regeneration, and equalization, to be realized at very high data rates.1 Although electronical approaches are mature and accelerated by large-scale IC integration, all-optical signal processing offers a number of advantages, most notably avoiding the need for optical-to-electricalto-optical (OEO) conversion The regeneration of signals, which compensates for transmission impairments including dispersion, nonlinear effects, and accumulation of amplified spontaneous emission (ASE) noise, will extend reach and wavelength conversion is of interest for solving the problem of wavelength blocking at network nodes With higher network efficiency and greater scalability than their OEO counterparts, all-optical signal regeneration and wavelength conversion are two functions that will be necessary to support the ever-increasing aggregate bandwidth demand in optical communications.2 Furthermore, in terms of processing efficiency, it makes greater sense to process signals on different channels in a wavelength-division-multiplexed (WDM) transmission scenario simultaneously rather than handling each channel individually Consequently, many fiber-based solutions for multi-channel signal regeneration3–8 and multi-channel wavelength conversion9–14 have been proposed While these approaches indeed show the possibility to achieve multi-channel all-optical signal processing, they require careful dispersion management (which increases design complexity) to reduce or avoid unwanted inter-channel nonlinear interactions which otherwise degrade performance On the other side, significant efforts have been devoted to develop integrated solutions for all-optical signal processing to address issues related to compactness, energy efficiency, and cost efficiency Single-channel all-optical signal regeneration and wavelength conversion have been successfully demonstrated in passive chalcogenide waveguides15–19 and silicon-on-insulator (SOI) waveguides.20–27 In order to realize multi-channel processing in an integrated waveguide, signals 2378-0967/2016/1(8)/086104/9 1, 086104-1 © Author(s) 2016 086104-2 M Ma and L R Chen APL Photonics 1, 086104 (2016) can propagate bi-directionally in the nonlinear waveguide but this scheme is limited in terms of the number of channels that can be processed All-optical switching based on a nonlinear differential phase shift between two propagating modes in an elliptical-core two-mode fiber was reported in Ref 28 Similar to this multi-mode fiber-based nonlinear switch, integrated waveguides can be engineered to support a few propagating (spatial) modes which we can exploit to realize “parallel” signal processing This creates a new degree of freedom for scaling the number of channels that can be processed simultaneously In this paper, we harness nonlinear optical effects in a mode-selective manner in an integrated silicon photonic device to realize on-chip multi-channel and multi-functional signal processing In particular, we demonstrate XPM-based regenerative wavelength conversion of 10 Gb/s return-to-zero on-off keying (RZ-OOK) signals and achieve large conversion bandwidth (20 nm) on two channels with up to 1.9 dB improvement in receiver sensitivity during simultaneous regeneration and a power penalty of