Chip-scale dispersion engineering using chirped vertical gratings

Abstract

A strongly coupled, chirped Bragg grating made by sinusoidally modulating the sidewalls of a silicon waveguide is designed, fabricated, and experimentally characterized. By varying the device parameters, the operating wavelength, device bandwidth, sign (normal or anomalous), and magnitude of group-velocity dispersion may be engineered for specific photonic applications. Asymmetric Blackman apodization is best suited for maximizing the useable bandwidth while providing good ripple suppression. Dispersion values up to 7.0 x 10(5) ps/nm/km are demonstrated at 1.55 microm.

Monolithic nonlinear pulse compressor on a silicon chip

“…The anomalously dispersive grating is necessary to delay the red-shifted component and advance the blue-shifted component to approach a transform-limited pulse. The dispersive grating consists of two coupled, sinusoidally corrugated waveguide gratings 21,22 with different average widths for cross coupling of the forward propagating wave at the input waveguide and the backward propagating wave at the output waveguide to occur. A positive, linearly chirped period is applied to generate the required anomalous dispersion across the transmission bandwidth.…”

“…This dispersion may be distributed over the length of the nonlinear medium, leading to solitonic compression, or may be localized at the output of the nonlinear medium using a highly dispersive element. We recently reported the theory and operation of such a dispersive element in silicon 21,22 , thus opening up vast prospects for all-optical on-chip functionalities for which dispersion is a key requirement. Such an element has been absent in the on-chip nanophotonics toolkit, and to date, most integrated optics applications requiring dispersive elements required heterogeneous integration with fibre-based components, resulting in less compact systems.…”

High-extinction-ratio TE/TM selective Bragg grating filters on silicon-on-insulator

“…Integrated photonics devices are extremely popular and versatile components for telecommunication systems [1], quantum photonics [2,3],hybrid III-V on silicon lasers [4,5] and signal processing [6,7]. In these applications, the high index contrast offered by the silicon-on-insulator (SOI) photonic platform is of great benefit to component miniaturisation and dense integration [8].…”

Tunable optical delay line based on integrated grating-assisted contradirectional couplers

“…The delay lines have a slope of 33 ps/nm, indicating a positive chromatic dispersion of 5.5 × 10 6 ps∕nm · km, which is enhanced by 3.2 × 10 5 times compared to the dispersion of single-mode fiber with 17 ps/(nm·km) dispersion. Compared to recent research about dispersion engineering, our chip design may pave the way for on-chip large-dispersion units with a compact size [37][38][39]. With increasing applied voltage, a redshift occurs in both the spectral responses and group delay lines.…”

“…According to the analysis in Refs. [32,33] and tentative simulations, asymmetric cosine apodization is one of the most effective methods for ripple suppressions of transmission and group delay spectra. Thus, we adopt asymmetric cosine apodization; namely, the apodization function is only applied on the gratings near the input port.…”