Ultra-broadband polarization beam splitter with silicon subwavelength-grating waveguides

Abstract

An ultra-broadband polarization beam splitter (PBS) with low excess loss (EL) and a high extinction ratio (ER) is proposed and demonstrated for the case with 340 nm thick silicon-on-insulator waveguides. Here the PBS is realized by using cascaded adiabatic dual-core tapers, which consist of a strip core and a subwavelength-grating core. For the designed PBS, which has a 33.6 µm long mode-evolution region, the ELs are &lt;<!-- 0.3 d B , and the ERs are &gt; 20 d B for both TE and TM polarizations in an ultra-broad bandwidth of &gt; 270 n m (1400–1670 nm) in theory. For the fabricated PBS, the measured bandwidths for achieving ERs of ∼ 20 and ∼ 25 d B are 240 and 220 nm, while the 1 dB bandwidth is as large as 230 nm, which are the largest bandwidths reported to date, to the best of our knowledge.

Subwavelength silicon photonics for on-chip mode-manipulation

“…More recently, an ultra-broad PBS with high performances was proposed and realized for the case of h co =340 nm by introducing cascaded SWG-assisted dual-core adiabatic tapers [75], as shown in Fig. 3(b).…”

“…3 PBSs with 340-nm-thick SOI waveguides. a A PBS based on an ADC consisting of a narrow SOI strip waveguide and a wide SWG waveguide [65]; b A PBS based on SWG-assisted dual-core adiabatic tapers [75] reported to date for the PBSs on silicon. Such an ultra-broadband high-performance PBS is useful for many applications.…”

“…For the SWG-assisted PBS based on a hetero-anisotropic slab, there are ultra-broad bandwidths for achieving ER >20 dB and ER>25 dB, i.e., BW ER>20dB =~200 nm and BW ER>25dB = 170 nm [83], which is the highest one among the PBSs with h co =220 nm. For the case of h co =340 nm, the PBS based on SWG-assisted adiabatic dual-core tapers enables the highest bandwidths for achieving ER>20 dB and ER>25 dB, i.e., BW ER>20dB =~230 nm and BW ER>25dB =~200 nm [75]. On the other hand, it is noticed that there are very few on-chip PBSs with ER>30 dB, which is desired for the future applications.…”

Ultra-Broadband Polarization Beam Splitter Based on Cascaded Mach-Zehnder Interferometers Assisted by Effectively Anisotropic Structures

“…A PBS formed by SWG structures, working as two isolated waveguides for the TE polarization and MMI for the TM polarization, has achieved ER >20 dB and IL <1 dB over a bandwidth of 200nm experimentally [17]. In [18], a PBS using cascaded adiabatic dual-core tapers assisted by SWG structure gives ER > 20 dB over a bandwidth of 240 nm experimentally.…”

Integrated subwavelength gratings on a lithium niobate on insulator platform for mode and polarization manipulation

“…In the last few years, SWG waveguides have been employed as one of the most important components to lead breakthroughs in silicon photonics, particularly for on-chip mode and polarization manipulation. A wide range of SWG-based devices including mode (de)multiplexers 3 , multimode waveguide bends and crossings 4,5 , mode lters 6 , polarization beam splitters 7,8 , polarizers 9 , etc. have been demonstrated.…”