We demonstrate optical 2R regeneration in an integrated silicon device consisting of an 8-mm-long nanowaveguide followed by a ring-resonator bandpass filter. The regeneration process is based on nonlinear spectral broadening in the waveguide and subsequent spectral filtering through the ring resonator. We measure the nonlinear power transfer function for the device and find an operating peak power of 6 W. Measurements indicate that the output pulse width is determined only by the bandwidth of the bandpass filter. Numerical modeling of the nonlinear process including free-carrier effects shows that this device can be used for all-optical regeneration at telecommunication data rates.
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"The above motivations led to considerable research efforts on nonlinear silicon photonics in recent years2627282930. Nonlinear effects such as SRS6768697071727374757677787980818283, self-and cross-phase modulation (SPM and XPM)8485868788899091 , fourwave mixing (FWM)9293949596979899100101102 , and supercontinuum gen- eration [60, 61,103104105106107108 are actively investigated. The main focus is on the near-IR wavelength range, around the telecom window. "
[Show abstract][Hide abstract]ABSTRACT: Group IV photonics hold great potential for nonlinear applications in the near- and mid-infrared (IR) wavelength ranges, exhibiting strong nonlinearities in bulk materials, high index contrast, CMOS compatibility, and cost-effectiveness. In this paper, we review our recent numerical work on various types of silicon and germanium waveguides for octave-spanning ultrafast nonlinear applications. We discuss the material properties of silicon, silicon nitride, silicon nano-crystals, silica, germanium, and chalcogenide glasses including arsenic sulfide and arsenic selenide to use them for waveguide core, cladding and slot layer. The waveguides are analyzed and improved for four spectrum ranges from visible, near-IR to mid-IR, with material dispersion given by Sellmeier equations and wavelength-dependent nonlinear Kerr index taken into account. Broadband dispersion engineering is emphasized as a critical approach to achieving on-chip octavespanning nonlinear functions. These include octave-wide supercontinuum generation, ultrashort pulse compression to sub-cycle level, and mode-locked Kerr frequency comb generation based on few-cycle cavity solitons, which are potentially useful for next-generation optical communications, signal processing, imaging and sensing applications.
"Many FWM experiments have equally been performed with pulses, where waveguide devices are preferred over cavities due to the limited bandwidth of typical resonances. Multiple applications in a host of optical platforms have been reported, including all-optical regeneration and demultiplexing in chalcogenides [104,105], silicon , GaAs [47,96], silica photonic crystal fibers , as well as in Hydex® [ "
[Show abstract][Hide abstract]ABSTRACT: We review our recent progresses on frequency conversion in integrated
devices, focusing primarily on experiments based on strip-loaded and
quantum-well intermixed AlGaAs waveguides, and on CMOS-compatible high-index
doped silica glass waveguides. The former includes both second- and third-order
interactions, demonstrating wavelength conversion by tunable
difference-frequency generation over a bandwidth of more than nm, as well as
broadband self-phase modulation and tunable four-wave mixing. The latter
includes four-wave mixing using low-power continuous-wave light in microring
resonators as well as hyper-parametric oscillation in a high quality factor
resonator, towards the realization of an integrated multiple wavelength source
with important applications for telecommunications, spectroscopy, and
"8 , corresponding to the long pulse (113 ps) regime. Although distortion is inconvenient in most photonic systems, it can typically be cleaned up by another device ,  . The nature of the distortion can also help understand complicated internal resonator dynamics. "
[Show abstract][Hide abstract]ABSTRACT: We propose a novel all-optical integrated thresholder called the dual resonator enhanced asymmetric Mach–Zehnder interferometer (DREAM). Unlike prior integrated photonic devices, the DREAM exhibits properties of stable binary decision making, outputting a constant “one” power value for signals above a certain power level and “zero” for signals of lower powers. This thresholding shape arises from the interference of complementary nonlinear effects of two microring resonators (MRR), one in each arm of a Mach–Zehnder interferometer (MZI). The proposed de- vice performs several orders of magnitude better in size, decision latency, energy efficiency, and stability compared to fiber-based methods of optical thresholding. It is best suited for application in densely integrated systems where rapid conversion between analog and digital signal domains is ubiquitous, such as hybrid analog-digital and neuromorphic processing architectures.
We derive analytical steady-state solutions to the nonlinear MRR, which enable design simulation, optimization, and au- tomation of a continuous signal thresholder about three orders of magnitude faster than with numerical simulation. Additional numerical simulations indicate the possibility of a 50 GHz pulse thresholder with a 380 pJ switching threshold in a silicon-on-insulator (SOI) platform. The proposed circuit design techniques are potentially applicable to a wide range of materials, waveguide platforms, and resonator types, but for concreteness, we limit the focus of this paper to MRRs in SOI.