Broadband and compact polarization beam splitter based on an asymmetrical directional coupler with extra optimizing designs.

In this paper, a novel, to the best of our knowledge, polarization beam splitter (PBS) based on an asymmetrical directional coupler (DC) was proposed, which consists of a strip waveguide (WG) and a ${{\rm Si}_3}{{\rm N}_4}$Si3N4 loaded horizontal slot WG. By carefully adjusting the geometric parameters of the DC, the phase match condition between these two WGs can be satisfied for the transverse magnetic (TM) polarization, while the coupling efficiency of the transverse electric (TE) polarization is frustrated due to the large phase mismatch. The extra optimizing designs include adding filters to the output ports as well as introducing the tapered structure into the DC, which is settled by the particle swarm optimizing (PSO) algorithm so that the performance of the proposed PBS is improved over a broadband range. Numerical simulations show that the bandwidths for the extinction ratio (ER) $ \gt {20}\;{\rm dB}$>20dB, 30 dB, and 40 dB are 160 nm, 95 nm, and 50 nm, respectively, with insertion loss (IL) $ \lt {1}\;{\rm dB}$<1dB for the wavelength of 1.49-1.58 µm. The analysis of the deviations demonstrates that the proposed PBS allows high fabrication tolerances.

[1]  Sailing He,et al.  Proposal for a Grating Waveguide Serving as Both a Polarization Splitter and an Efficient Coupler for Silicon-on-Insulator Nanophotonic Circuits , 2009 .

[2]  Daoxin Dai,et al.  Compact polarization beam splitter for silicon photonic integrated circuits with a 340-nm-thick silicon core layer. , 2017, Optics letters.

[3]  Qianfan Xu,et al.  Guiding and confining light in void nanostructure. , 2004, Optics letters.

[4]  David T. Neilson,et al.  Silicon photonic devices and integrated circuits , 2014 .

[5]  Yaocheng Shi,et al.  Ultra-broadband silicon polarization splitter-rotator based on the multi-mode waveguide. , 2017, Optics express.

[6]  E. Skafidas,et al.  Low-Loss and Broadband $2 \times 2$ Polarization Beam Splitter Based on Silicon Nitride Platform , 2016, IEEE Photonics Technology Letters.

[7]  Tianye Huang,et al.  Compact polarization beam splitter assisted by subwavelength grating in triple-waveguide directional coupler. , 2019, Applied optics.

[8]  Daoxin Dai,et al.  Realization of a compact polarization splitter-rotator on silicon. , 2016, Optics letters.

[9]  Lei Wang,et al.  Broadband, Fabrication-Tolerant Polarization Beam Splitters Based on a Tapered Directional Coupler , 2016, IEEE Photonics Technology Letters.

[10]  Lin Zhang,et al.  Fano-Like Resonance in an All-in-Fiber Structure , 2019, IEEE Photonics Journal.

[11]  Tymon Barwicz,et al.  Polarization rotator-splitters in standard active silicon photonics platforms. , 2014, Optics express.

[12]  Mo Mojahedi,et al.  Realization of an ultra-compact polarization beam splitter using asymmetric MMI based on silicon nitride / silicon-on-insulator platform. , 2017, Optics express.

[13]  Daoxin Dai,et al.  Low-loss ultracompact transverse-magnetic-pass polarizer with a silicon subwavelength grating waveguide. , 2014, Optics letters.

[14]  Dominic Goodwill,et al.  Tri-layer silicon nitride-on-silicon photonic platform for ultra-low-loss crossings and interlayer transitions. , 2017, Optics express.

[15]  Daoxin Dai,et al.  Extremely small polarization beam splitter based on a multimode interference coupler with a silicon hybrid plasmonic waveguide. , 2014, Optics letters.

[16]  Shiyang Zhu,et al.  CMOS compatible polarization splitter using hybrid plasmonic waveguide. , 2012, Optics express.

[17]  Xingjun Wang,et al.  CMOS-compatible and fabrication-tolerant MMI-based polarization beam splitter , 2015 .

[18]  Anatol Khilo,et al.  Compact silicon TE-pass polarizer using adiabatically-bent fully-etched waveguides. , 2018, Optics express.

[19]  C. Doerr,et al.  Compact polarization rotator on silicon for polarization-diversified circuits. , 2011, Optics letters.

[20]  Daoxin Dai,et al.  Ultra-broadband high-performance polarizing beam splitter on silicon. , 2017, Optics express.

[21]  Xinwan Li,et al.  Efficient silicon polarization rotator based on mode-hybridization in a double-stair waveguide. , 2015, Optics express.

[22]  Guo-Qiang Lo,et al.  Polarization rotator-splitters and controllers in a Si3N4-on-SOI integrated photonics platform. , 2014, Optics express.

[23]  John E. Bowers,et al.  Compact Polarization Beam Splitter Using an Asymmetrical Mach–Zehnder Interferometer Based on Silicon-on-Insulator Waveguides , 2012, IEEE Photonics Technology Letters.

[24]  S. Chandrasekhar,et al.  Monolithic Silicon Photonic Integrated Circuits for Compact 100 $^{+}$Gb/s Coherent Optical Receivers and Transmitters , 2014, IEEE Journal of Selected Topics in Quantum Electronics.

[25]  T. Tsuchizawa,et al.  Silicon photonic circuit with polarization diversity. , 2008, Optics express.

[26]  Daoxin Dai,et al.  Advanced Passive Silicon Photonic Devices With Asymmetric Waveguide Structures , 2018, Proceedings of the IEEE.

[27]  Kresten Yvind,et al.  Silicon-on-insulator polarization splitting and rotating device for polarization diversity circuits. , 2011, Optics express.

[28]  Guang-Can Guo,et al.  On-chip coherent conversion of photonic quantum entanglement between different degrees of freedom , 2016, Nature Communications.

[29]  Chih-Wei Hsu,et al.  8.13  μm in length and CMOS compatible polarization beam splitter based on an asymmetrical directional coupler. , 2016, Applied optics.

[30]  Sailing He,et al.  On‐chip silicon 8‐channel hybrid (de)multiplexer enabling simultaneous mode‐ and polarization‐division‐multiplexing , 2014 .

[31]  Guo-Qiang Lo,et al.  Ultracompact silicon-on-insulator polarization rotator for polarization-diversified circuits. , 2014, Optics letters.