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Nonlinear phenomena are investigated in a topological photonic valley Hall insulator (VHI) using a Kagome system designed to have localized topological boundary state (TBS) at telecommunications wavelengths. Valley Hall topologically protected nonlinear phenomena are demonstrated. Similar transmission properties and parametric wavelength conversion of up to −12 dB are experimentally achieved using sub‐milliwatt average powers in a zigzag interface without back‐scattering, compared with a straight interface. Furthermore, a 7 dB slow light enhancement is observed in the conversion efficiency near the red edge in the transmission band of the boundary state, demonstrating how slow light‐induced backscattering may be circumvented by leveraging the topologically protected boundary state. A Kerr‐induced delocalization of the valley Hall topological state (VHTS) is further experimentally observed, which can be harnessed to control the properties of topological edge states. [ABSTRACT FROM AUTHOR]

Solitons have been a subject of intense intellectual curiosity and an avenue for a plethora of applications since they are first observed in water waves. Optical solitons, in particular, have seen tremendous progress, starting from their first theoretical predictions in optical fiber in 1973. On the 50th anniversary of this seminal work from Haseagawa and Tappert, a review is provided on the progress in an important class of optical solitons, the Bragg soliton. Bragg solitons are optical solitons which exist in structures periodic in one dimension. The history of Bragg solitons is described, including the most salient advancements made both in theory and experiments. Recent progress made in integrated photonic devices and their associated design advantages are highlighted, with particular emphasis on how these have facilitated the realization of Bragg soliton dynamics on a chip and their optical processing functions. A discussion and future outlook for this burgeoning field provides a perspective on how Bragg solitons may impact the field of photonics and future applications. [ABSTRACT FROM AUTHOR]

High‐speed data movement in data center communications and telecommunications is the cornerstone of society's connectivity. It serves as a critical driver of economic activity, social networks, and education. Complementary metal‐oxide semiconductor compatible silicon‐based photonic integrated circuits have proliferated transceiver technology, owing to their ease of integration with application‐specific integrated circuits and mass manufacturability. Fiber impairments in the transmission of high‐speed data stem from both optical attenuation and optical dispersion. As data rates scale and modulation formats advance, the impact of fiber dispersion even at shorter reaches becomes more important to address. In this review article, recent advancements made in integrated, chip‐scale dispersion compensation solutions are covered. The focus on chip‐scale devices stems from their ability to be easily integrated within the transmitter or receiver chip of transceivers. Future perspectives on how these devices may become commonplace within transceivers and their potential impact are discussed. [ABSTRACT FROM AUTHOR]

CMOS-compatible nonlinear optics platforms with negligible nonlinear losses and high nonlinearity are of great merit. Silicon, silicon nitride and Hydex glass have made significant headway in nonlinear optical signal processing, though none of these platforms possesses the highly sought after combination of high nonlinearity and negligible nonlinear losses. In this manuscript, we present a nonlinear optics platform based on silicon-rich nitride, deposited at a low temperature of 250°C compatible with back-end CMOS processing. The silicon-rich nitride is designed and engineered in composition to have a bandgap of 2.05 eV, such that the two-photon absorption edge is well below 1.55 μm. The designed and developed waveguides have a nonlinear parameter of 550 W−1/m, 500 times larger than that in silicon nitride waveguides, while at the same time not possessing two-photon and free-carrier losses. Using 500-fs pulses, we generate supercontinuum exceeding 0.6 of an octave. [ABSTRACT FROM AUTHOR]

All-optical signal processing on nonlinear photonic chips is a burgeoning field. These processes include light generation, optical regeneration and pulse metrology. Nonlinear photonic chips offer the benefits of small footprints, significantly larger nonlinear parameters and flexibility in generating dispersion. The nonlinear compression of optical pulses relies on a delicate balance of a material's nonlinearity and optical dispersion. Recent developments in dispersion engineering on a chip are proving to be key enablers of high-efficiency integrated optical pulse compression. We review the recent advances made in optical pulse compression based on nonlinear photonic chips, as well as the future outlook and challenges that remain to be solved. [ABSTRACT FROM AUTHOR]

Highlights from the article: Bragg Soliton Fission: Bragg Soliton Compression and Fission on CMOS-Compatible Ultra-Silicon-Rich Nitride (Laser Photonics Rev. 13(8)/2019) In article number 1900114, Ezgi Sahin, Dawn T. H. Tan, Benjamin J. Eggleton, and co-workers describe how optical pulses propagating through a nonlinear ultra-silicon-rich nitride (USRN) grating experience high anomalous group-velocity dispersion at the photonic band edge. Temporal dynamics of Bragg soliton-effect compression and fission are experimentally observed.

Higher‐order soliton dynamics, specifically soliton compression and fission, underpin crucial applications in ultrafast optics, communications, and signal processing. Bragg solitons exploit the strong dispersive properties of periodic media near the photonic band edge. This enables soliton dynamics to occur in very short propagation distances, opening avenues to harness soliton compression and fission in integrated photonic platforms. However, implementation in complementary metal‐oxide semiconductor (CMOS)‐compatible platforms has been hindered by the strong nonlinear loss that dominates the propagation in silicon and the low‐optical nonlinearity of traditional silicon nitride. Here, CMOS‐compatible, on‐chip Bragg solitons, are presented with a soliton‐effect pulse compression with a factor of × 5.7, along with time‐resolved measurements of soliton fission on a CMOS‐compatible photonic circuit platform. These observations are enabled by the combination of a unique cladding‐modulated Bragg grating design and the high nonlinearity and negligible nonlinear loss of compositionally engineered ultra‐silicon‐rich nitride (USRN: Si7N3). [ABSTRACT FROM AUTHOR]