Experimental demonstration of metamaterial anisotropy engineering for broadband on-chip polarization beam splitting

Abstract

Subwavelength metamaterials exhibit a strong anisotropy that can be leveraged to implement high-performance polarization handling devices in silicon-on-insulator. Whereas these devices benefit from single-etch step fabrication, many of them require small feature sizes or specialized cladding materials. The anisotropic response of subwavelength metamaterials can be further engineered by tilting its constituent elements away from the optical axis, providing an additional degree of freedom in the design. In this work, we demonstrate this feature through the design, fabrication and experimental characterization of a robust multimode interference polarization beam splitter based on tilted subwavelength gratings. A 110-nm minimum feature size and a standard silicon dioxide cladding are maintained. The resulting device exhibits insertion loss as low as 1 dB, an extinction ratio better than 13 dB in a 120-nm bandwidth, and robust tolerances to fabrication deviations.

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

“…[39,40] One straightforward approach is to build an ADC by combining regular waveguides with SWG waveguides, as demonstrated in refs. [41][42][43][44][45][46][47][48]. For most of these designs, polarization selectivity is still offered by geometric asymmetry, therefore it does not deterministically improve the optical bandwidth.…”

An Ultra-Broadband Design of TM-Pass/TE-Stop Polarizer Based on Multistage Bragg Gratings

“…In this case, there is a great demand to produce a polarization management device to perform polarization states manipulation in PICs. To date, a number of device structures have been reported to perform various polarization control functions, including polarization beam splitters (PBS) [2][3][4], polarization splitter-rotators (PSR) [5][6][7], and polarizers [8][9][10]. Theoretically, the PBS and PSR require restrict phase matching conditions to realize splitting operations so their structural geometries have to be carefully controlled in design and fabrication.…”

Bricked Subwavelength Gratings: A Tailorable On‐Chip Metamaterial Topology

“…By periodically patterning waveguides at the subwavelength scale, a wide range of equivalent refractive indexes can be synthesized lithographically on a chip. [15][16][17][18] What is more, with the ability to engineer dispersion and anisotropy these metamaterials are enabling completely new design strategies yielding devices with unprecedented performance, including ultra-broadband nanophotonic components, [19,20] metalenses, [21][22][23] densely spaced waveguides, [24] polarization management devices, [25][26][27][28][29][30] low crosstalk bends, [31] or high sensitivity waveguide sensors. [32,33] However, to avoid Bragg resonances, subwavelength grating (SWG) metamaterials often require fabrication resolutions of 100 nm and below at telecom wavelengths.…”