Ultra-compact mode-order converters with dielectric slots are demonstrated on a silicon-on-insulator platform. We propose a mode converter that converts the TE0 mode into the TE1 mode with an ultra-small footprint of only 0.8×1.2µ. The measured insertion loss is less than 1.2 dB from 1520 nm to 1570 nm. To reduce the insertion loss, we further optimize the structure and design two mode converters that convert the TE0 mode into the TE1 mode and the TE2 mode with footprints of 0.88×2.3µ and 1.4×2.4µ, respectively. Their measured insertion losses are both less than 0.5 dB. Additionally, the proposed devices are cascadable and scalable for high-order mode conversion.
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http://dx.doi.org/10.1364/OL.391748 | DOI Listing |
Mode-order conversion devices can provide a flexible platform to achieve mode coupling and optimizing in mode division multiplex (MDM) that can eliminate the restrain of capacity and density in photonic integration and communication. However, mode-order converters based on traditional photonic crystal (PC) waveguides are susceptible to defects, which always render device incapacitation in mode-order conversion. Herein, a mode converter designed by the Mach-Zehnder interferometer (MZI) structure is proposed to manipulate the conversion of topological edge states (TESs) based on Chern insulators consisting of gyromagnetic PCs.
View Article and Find Full Text PDFMode-order converters, transforming a given mode into the desired mode, have an important implication for the multimode division multiplexing technology. Considerable mode-order conversion schemes have been reported on the silicon-on-insulator platform. However, most of them can only convert the fundamental mode to one or two specific higher-order modes with low scalability and flexibility, and the mode conversion between higher-order modes cannot be achieved unless a total redesign or a cascade is carried out.
View Article and Find Full Text PDFA compact and broadband silicon mode-order converter (MOC) scheme by employing reciprocal mode evolution between asymmetric input/output taper and bricked subwavelength gratings (BSWG) is proposed. In the proposed MOC, a quasi-TE mode is generated in the BSWG region, which can be regarded as an effective bridge between the two TE modes to be converted. Flexible mode conversion can be realized by only choosing appropriate structure parameters for specific mode transitions between input/output modes and the quasi-TE mode.
View Article and Find Full Text PDFIn this Letter, photonic crystal (PC) waveguide-based interferometer design is studied; spectral as well as temporal analyses have been conducted. Intentional structural modifications inside the interferometer trigger Fano resonances, allowing for extraordinary optical effects, such as enhanced beam recirculation and mode-order conversion. The proposed Mach-Zehnder-Fano interferometer is compatible with conventional silicon-on-insulator (SOI) technology and consists of two arms: the lower arm, with no point defects, creates continuum states, whereas the upper arm, including a Fano defect, creates discrete states.
View Article and Find Full Text PDFBragg-gratings have been frequently used to design compact and high extinction ratio (ER) on-chip polarizers. However, the strong reflection of the unwanted polarization may deteriorate the performance of the light source or cause unwanted interferences. In this paper, we propose a Bragg-grating-based all-silicon TM-pass polarizer with low reflection, low insertion loss (IL) and high ER.
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