Ultracompact, polarization-independent, and highly scalable optical power splitting model employing fan-out bending metamaterials

Abstract

Optical power splitters (OPSs) are essential components in the photonic integrated circuits. Considerable power splitting schemes have been reported on the silicon-on-insulator platform. However, the corresponding device lengths are enlarged, and polarization-sensitive operations are usually encountered when the splitting channels are increased from two to five. In this paper, a novel power splitting model is proposed to overcome these limitations. Here, fan-out bending subwavelength grating (FBSWG) metamaterials instead of classical straight SWGs are leveraged to expand the input TE/TM mode in an ultracompact region and further bend its wavefronts. By using N -angled tapers to match bending wavefronts, the light expanded by FBSWGs can be collected and evenly distributed into N output channels. Based on such a model, three OPSs are designed and experimentally demonstrated, which are the shortest polarization-independent 1 × 3 , 1 × 4 , and 1 × 5 OPSs reported until now to our knowledge. The characterizations show low insertion losses ( < 1.2    dB , < 1.35    dB , and < 1.65    dB ) and uniformities ( < 0.9    dB , < 1    dB , and < 1    dB ) over bandwidths of 54 nm, 49 nm, and 38 nm for the 1 × 3 , 1 × 4 , and 1 × 5 OPSs, respectively. For the first time, an ultracompact device length of < 4.3    μm and a polarization-independent operation can be maintained simultaneously as the output splitting channels are increased.