On‐Chip Metamaterial Enabled Wavelength (De)Multiplexer

Abstract

Wavelength‐division multiplexing (WDM) technology can offer considerable parallelism for large‐capacity data communications. While several configurations have been demonstrated to realize on‐chip WDM systems, their practical applications might be hindered by large footprints or compromised performances. Recently, metamaterial‐assisted silicon photonics is emerging for on‐chip light manipulation by subwavelength‐scale control of optical wavefronts. They can reach more compact footprints and broadband functionalities beyond the classical waveguide‐based architectures. Herein, wavelength (de)multiplexers are experimentally demonstrated in the subwavelength‐structured metamaterials regime with highly compact footprints. Two‐dimensional metamaterials composed of quasi‐periodic dielectric perturbation arrays patterned on a multimode waveguide are proposed to stimulate multiple high‐order waveguide modes at different wavelengths, which are then coupled to different WDM channels by cascading mode (de)multiplexers. The four‐channel wavelength (de)multiplexer is demonstrated in a box‐like spectrum with a compact footprint of 2.5 × 250 µm2, with the measured losses less than 2 dB and channel crosstalk less than –14.3 dB. By varying the patterned metamaterial structures, the proposed devices also have the merits of flexible operating wavelengths and bandwidths. The concept features large scalability, compactness, and competitive performance, which can offer versatile on‐chip light manipulation and significantly improve the integration density for various on‐chip WDM optical systems.

Scalability of Large-Scale Photonic Integrated Circuits

“…Compared with copper lines, the capacity and the bandwidth density of the optical interconnect can be scaled by adopting high-level modulation formats, or by multiplexing signals into all the available physical dimensions, such as wavelength, − mode, − and polarization. , Currently, the state-of-the-art capacity of an optical multiplexing chip is on the order of 10 Tb/s . However, looking into the next 10 years and beyond, the current technologies are far from enough to enable Pb/s capacity on a chip.…”

High‐Performance Silicon Photonic Filter Using Subwavelength‐Structure Multimode Waveguide Gratings

“…Recently, silicon subwavelength gratings (SWGs) have been introduced to realize high-performance nanophotonic devices for on-chip mode/wavelength/ polarization manipulation, such as multimode waveguide crossings, [50] bent multimode waveguides, [51] polarization beam splitters, [52] and narrow/broad-band photonic filters. [35,53,54] In this paper, we propose and demonstrate a photonic filter with unprecedented performance by using multimode SWG (MSWG) structures. Particularly, the proposed photonic filter is composed of a two-channel mode (de)multiplexer and an MSWG with antisymmetric teeth, which enable the coupling between the forward fundamental mode and the first higherorder mode (which is anti-symmetric).…”

Metamaterial‐enabled Fully On‐Chip Polarization‐Handling Devices

“…[40][41][42][43][44] On the other hand, gradient index dielectric metamaterials have provided a forward-designed approach to manipulate waveguide mode-order conversions. [45][46][47][48][49] By offering desired phase distribution to satisfy the phase-matching conditions between different modes, it is possible to achieve highefficiency mode-order conversions with clear physical guidelines. However, these designs mainly focus on the coupling between different mode orders in the same polarization, and the manipulation of different polarization has yet to be explored.…”