CW3H.1.pdf CLEO:2013 Technical Digest © OSA 2013 Mid-Infrared Supercontinuum Generation in Silicon Waveguides Michael R.E. Lamont, 1,2,3,* Ryan K.W. Lau, 1 Austin Griffith, 2 Y. Henry Wen, 1 Yoshitomo Okawachi, 1 Michal Lipson, 2,3 and Alexander L. Gaeta 1,3 1 School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA 2 School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA 3 Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA *michael.lamont@cornell.edu Abstract: We demonstrate supercontinuum generation (SCG) spanning from telecom to mid- infrared wavelengths beyond 3.6 μm, using a silicon-on-insulator wire waveguide, which represents the first octave-spanning SCG from a silicon chip. 2013 Optical Society of America OCIS codes: (190.4390) Nonlinear optics, integrated optics; (320.6629) Supercontinuum generation. Supercontinuum generation (SCG) is of importance to many application fields, including spectroscopy and tomography. Developing a CMOS-compatible on-chip platform for SCG will advance many of these applications by providing high-volume, low-cost, integrated devices. Extending SCG to the mid-infrared (mid-IR) is necessary for applications such as gas sensing using molecular fingerprints at wavelengths above 2 μm. Silicon is particularly promising as a mid-IR platform since nonlinear losses are lower than at telecom wavelengths, yet the nonlinear refractive index remains high [1]. This platform has been used for four-wave mixing demonstrations [2-4], as well as for SCG up to 2525 nm [5]. However, the linear and nonlinear properties of silicon have not been fully explored at longer wavelengths, nor have wide bandwidths (BWs) been achieved by channel waveguides in the mid-IR. Although chalcogenide channel waveguides have been used to achieve SCG at longer wavelengths, cladding absorption prevents broad BWs [6]. Chalcogenide fiber tapers and microstructured fibers have met with more success and produced octave-spanning BW into mid-IR wavelengths [7, 8]. The broadest SCG to date was demonstrated in a telluride photonic crystal fiber, having a BW over 4 μm up to a wavelength of 4870 nm [9]. Here we present SCG spanning from 1.51 μm to 3.67 μm, which corresponds to 1.3 octaves. The waveguide is standard silicon-on-insulator (SOI) with dimensions of 320 × 1210 nm, and 2-cm long and engineered to have TE zero-dispersion points (ZDPs) at 2.2 μm and 3.0 μm. The waveguide was pumped with 300 fs pulses using an optical parametric oscillator (OPO) at a repetition rate of 80 MHz. The output OPO wavelength λ P is varied from 2.165 μm to 2.501 μm. The average OPO output power depends strongly on wavelength and is 17 and 3 mW at the shortest and longest wavelengths, respectively. The pulses were coupled in and out of the waveguide using aspheric lenses with an estimated in-chip peak power ranging from 20 to 110 W. The output spectra are measured using a Fourier transform infrared spectrometer (FTIR) with a liquid nitrogen-cooled InSb detector. 1 1.5 2 2.5 3 3.5 4 Output Spectrum (10dB/div) Wavelength (μm) λ P = 2.501μm 2.373μm 2.251μm 2.165μm FTIR Output λ P mid-IR dispersive wave telecom dispersive wave Fig. 1. Output spectra as the pump wavelength p is tuned from 2.165 μm to 2.501 μm, as denoted by the dotted line. The dashed lines show the resulting shift of the dispersive waves generated in both the telecom and mid-IR regions.