Wideband silicon photonic polarization beamsplitter based on point-symmetric cascaded broadband couplers

Abstract

We design and demonstrate a wideband silicon photonic polarization beamsplitter on a silicon-on-insulator platform. The device consists of two 3 dB broadband couplers cascaded in a point-symmetric network. The transverse electric (TE) and transverse magnetic (TM) modes are coupled to different output ports due to a large difference between their coupling strengths. The device exhibits large isolation at both the two output ports, of more than 20 dB over a large bandwidth of 125 nm, and a small excess loss, of less than 0.5 dB for the entire C-band.

Broadband integrated polarization beam splitting based on anisotropic adiabatic transfer of light

“…This is mainly achieved due to high refractive index contrast and reduced dimensions. Various structures have been reported, e.g., highly birefringent bent couplers [6,7], asymmetric phase-controlled directional couplers [8,9], or multimode interference couplers sometimes combined with subwavelength gratings [10], photonic crystals [11], or metamaterials [12,13] to extend the wavelength bandwidth. These devices can reduce the device footprint, generally in exchange for tight fabrication tolerances along with precise and complex tuning of the waveguide structures.…”

Tailorable and Broadband On-Chip Optical Power Splitter

“…Conventional Y-junctions typically have a 1-dB insertion loss and a 3-dB splitting ratio due to fabrication imperfections [11,12]. In the case of directional couplers, the power splitting can be designed by controlling the coupling length and distance between the two waveguides, but the coupling ratio strongly depends on the input wavelengths [8,13]. Recently, curved directional coupler and its combination with straight directional couplers show small footprints, low loss, and ultra-broadband power splitting, but they need careful design in coupling regions [14,15].…”

CMOS-compatible Si-wire polarization beam splitter based on wavelength-insensitive coupler

“…Recently, various types of silicon-based PBSs have been proposed based on directional couplers (DCs) [3,4,5,6,7,8,9], multimode interference couplers [10,11], gratings [12], and Mach-Zehnder interferometers [13]. Among them, DCs are simple structure and easy to design.…”

“…Therefore, it is difficult to obtain the broadband operation of DC-based PBSs. In [8,9], PBSs based on two-cascaded 3-dB DCs were proposed to overcome the problem. In our previous paper [8], a PBS based on a wavelength-insensitive coupler (WINC) composed of rounded delay lines with a point symmetric layout [13] was theoretically proposed.…”