Silicon Nanowire-Assisted High Uniform Arrayed Waveguide Grating

Abstract

Determining how to improve the non-uniformity of arrayed waveguide grating (AWG) is of great significance for dense wavelength division multiplexing (DWDM) systems. In this work, a silicon nanowire-assisted AWG structure is proposed, which can achieve high uniformity with a low insertion loss. The article compares the effect of nanowire number and shape on uniformity and insertion loss, finding that double nanowires provide the best performance. Double nanowires with a width of 230 nm and length of 3.5 μm can consist of a slot configuration between arrayed waveguides, both connecting to the star coupler and spacing 165 nm from the waveguides. Compared with conventional 8- and 16-channel AWGs with channel spacing of 200 GHz, the non-uniformity of the presented structure can be improved from 1.09 and 1.6 dB to 0.24 and 0.63 dB, respectively. The overall footprint of the device would remain identical, which is 276 × 299 or 258 × 303 μm2 for the 8- or 16-channel AWG. The present high uniformity design is simple and easy to fabricate without any additional insertion loss, which is expected to be widely applied in the highly integrated DWDM systems.

Sidewall Corrugation-Modulated Phase-Apodized Silicon Grating Filter

“…For the multi-mode waveguide, if the excited TE 0 mode in the strip waveguide meets the phase-matching condition, the grating will reversely couple it to the backward TE 1 mode. On the other hand, if the wavelength does not meet the phase-matching condition, the TE 0 mode remains intact when propagating through the grating [ 31 ]. TE 0 and TE 1 modes can be coupled when the phase-matching condition is satisfied, which can be expressed as [ 32 ] where n eff 0 and n eff 1 are the effective refractive indices of TE 0 and TE 1 modes, respectively, and λ B is the resonance wavelength.…”

Distinct anharmonic characteristics of phonon-driven lattice thermal conductivity and thermal expansion in bulk MoSe2 and WSe2

“…The effect of higherordered scattering processes and their temperature dependence was also observed in strongly anharmonic superionics and 2-d materials, including WS 2 and graphene, where the impact of higher-order anharmonicity on thermal conductivity is found to be signicant. [71][72][73][74][75][76][77][78][79] Lattice thermal expansion behaviour and phonon anharmonicity Thermal expansion is also associated with anharmonicity on the potential energy surface. By knowing the phonon frequency shis with temperature and volume, one can estimate how the material would behave at a given temperature.…”