Abstract

All-optical signal processing has been demonstrated extensively in Si including demultiplexing at 160Gb/s via four-wave mixing (FWM) [1] and optical regeneration [2], as well as in chalcogenide glass (ChG) waveguides[3]. The efficiency of all-optical devices can be improved by increasing the nonlinear parameter, γ = ω n₂ / c A_eff (A_eff is the waveguide effective area, n₂ is the Kerr nonlinearity) as well as by using resonant structures to enhance the local field intensity. Semiconductors and ChG offer excellent optical confinement and a high n₂ that has produced γ’s of 200,000 W⁻¹ km⁻¹ for Si nanowires [2], and 93,400 W⁻¹ km⁻¹ in ChG nanotapers [4]. Yet silicon suffers from a poor intrinsic nonlinear figure of merit (FOM = n₂ / (βλ), where β is the two-photon absorption coefficient) due to two-photon absorption (TPA) and the resulting free carriers [5]. Here, we report a wide range of functions in a CMOS compatible high index doped silica glass platform, including an integrated multiple wavelength source [6,7], an ultra-high repetition rate modelocked laser [8], and an all-optical integrator[9]. We achieve CW oscillation in a Q=1.2 million micro-ring resonator with a slope efficiency of 7.4% (single oscillating mode, single port), a threshold power of 54mW, and frequency spacings from 200GHz to > 6THz. We also achieve modelocking with repetition rates as high as 800GHz [9]. We also report novel functions in ultra-long (45cm) spiral waveguides, including a time-lens optical oscilloscope and parametric amplifier with > 15dB of gain [10]. The success of these devices is due to very low linear loss, negligible nonlinear loss (up to 25GW/cm²), and a high γ ≅ 233W⁻¹km⁻¹. The low loss, design flexibility, and CMOS compatibility of this platform will enable devices for telecommunications, computing, sensing, metrology and other areas.

© 2011 Optical Society of America