Meta‐Structured Silicon Nanophotonic Polarization Beam Splitter with an Optical Bandwidth of 415 nm

Abstract

The polarization beam splitter (PBS) is a pivotal element in the polarization management of free‐space optical instruments and systems. Photonic integrated circuits for sensing, imaging, communications, and quantum‐information processing also have needs for monolithically integrated PBSs with an ultra‐broad optical bandwidth. In this paper, a novel silicon nanophotonic PBS inspired by the crystalline Glan–Thompson prism but implemented with silicon subwavelength‐grating (SWG) metamaterials is presented. Due to the tailored artificial anisotropy of SWGs, the meta‐prism functions like a thin‐film reflector or a waveguide crossing for different polarizations. Thus, the incident light can be steered with strong polarization selectivity and negligible wavelength dependence. Unlike conventional PBS designs, the routing of polarized light is enabled by the wavelength‐independent total internal reflection in anisotropy‐engineered effective media, thereby breaking the bandwidth limit. The device footprint is as small as ≈15 × 7 µm2. Low insertion losses of 0.6–1.7 dB and high extinction ratios of 20–30 dB are experimentally achieved spanning a record broad bandwidth of over 415 nm, ranging from 1.26 to 1.675 µm wavelength. These results represent, to the best of their knowledge, the most broadband integrated PBS ever demonstrated to date.

Conical holes arrays for 2 × 2 ports division

“…A two-dimensional (2D) metal grating is a type of metasurface with periodic patterns structured in two directions. In various optical applications such as interferometers [4][5][6], chromatic dispersion [7,8], and optical communications [9], a beam splitter [10][11][12] plays a significant role in separating light polarization, wavelength, and power, due to their ability to split an incoming light beam into two or more separate beams. Various methods and structures, including photonic crystals [13][14][15], wave plates [16,17], and metasurface [3,[18][19][20][21], are used to implement beam splitters.…”

Spatial and Polarization Division Multiplexing Harnessing On‐Chip Optical Beam Forming

“…[6][7][8][9][10][11][12][13] Similarly, multiple devices have been reported for PDM, including MMIs, Mach-Zehnder interferometers (MZIs), diverse types of DCs (i.e., symmetric, asymmetric, tapered, bent, and based on extreme skin-depth), photonic crystals, slot waveguides, and subwavelength and tilted nano-gratings. [14][15][16][17][18][19][20][21][22][23][24][25][26][27] Despite the great diversity of proposed solutions, crosstalk still remains as one of the main impairments in high-speed optical communications, especially in systems with a high-channel count. An increased crosstalk has a negative impact on the link performance in terms of bit-error-rate (BER) and ultimately results in a power penalty that jeopardizes low power consumption.…”