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A compact and polarization-independent three-guide power splitter using subwavelength gratings (SWGs) on the SOI platform is proposed and analyzed in detail, where the SWG structures are located at both sides of the central input waveguide and the inner sides of the two outside waveguides. The introduced SWG structures can effectively enhance the coupling strength for TE mode, while that for TM mode is hardly affected. Consequently, by carefully choosing the structural parameters, the input TE mode can be evenly coupled from the central input waveguide to the outside waveguides, with the same coupling length for TM mode, thus a polarization-independent power splitter is realized. Results show that a compact power splitter of 8.5 μ m in coupling length is achieved with an insertion loss (IL) of 0.1 dB (0.085 dB) and reflection loss (RL) of −39 dB (−46 dB) for TE (TM) mode at the wavelength of 1. 55 μ m , and the operation bandwidth is up to 170 nm (from 1.48 to 1. 65 μ m) when IL <0.8 dB, RL <−20 dB and splitting ratio (SR) ∼ 1.001 for both polarizations. In addition, fabrication tolerances to the key structural parameters are presented and field evolution through the device is illustrated [ABSTRACT FROM AUTHOR]

A compact silicon-based polarization beam splitter (PBS) using directional couplers assisted with subwavelength grating (SWG) is proposed and analyzed in detail, where a conventional directional coupler at the input/output end and an SWG coupler in the middle together with SWG-based transitions between them are used. The introduced SWG structures can significantly improve the coupling strength for TE mode, whereas that for TM mode is hardly affected. Subsequently, by carefully choosing structural dimensions, the total coupling length for TM mode can be exactly twice that of TE mode, thus the two polarization states can be effectively separated so that a PBS is realized. Results show that a PBS with a coupling length of 10 μm is achieved, and the extinction ratio, insertion loss, and reflection loss are 23.38/31.78, 0.136/0.104, and −22.03 / − 26.91 dB, respectively, for TE/TM mode. In addition, fabrication tolerance to the key structural parameters and field evolution through the present device are both presented. [ABSTRACT FROM AUTHOR]