Article

CMOS compatible polarization splitter using hybrid plasmonic waveguide

Optics Express (Impact Factor: 3.49). 11/2012; 20(23):25345-55. DOI: 10.1364/OE.20.025345
Source: PubMed

ABSTRACT

We design and experimentally demonstrate an ultrashort integrated polarization splitter on silicon-on-insulator (SOI) platform. Our polarization splitter uses a hybrid plasmonic waveguide as the middle waveguide in a three-core arrangement to achieve large birefringence, allowing only transverse-magnetic (TM) polarized light to directionally couple to the cross port of the directional coupler. Finite-difference time-domain (FDTD) and eigenmode expansive (EME) calculations show that the splitter can achieve an extinction ratio of greater than 15 dB with less than 0.5 dB insertion losses. The polarization splitter was fabricated on SOI platform using standard complementary metal-oxide-semiconductor (CMOS) technology and measured at telecommunications wavelengths. Extinction ratios of 12.3 dB and 13.9 dB for the transverse-electric (TE) and TM polarizations were obtained, together with insertion losses of 2.8 dB and 6.0 dB.

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    • "To avoid the extra coupling and enhance the ER of the PS, S-bend is incorporated at the output port of the vertical HPW. Compared with those PSs based on three-guide DC structures reported earlier, the present scheme does not need to stratify the condition that the propagation constants of the three lowest-order modes must be evenly spaced [13], [14], thus this scheme can make the design more convenient. Moreover, the proposed scheme has relatively large design flexibility since the length of the horizontal and vertical HPWs can be optimized independently to achieve the optimal performance for TE and TM modes. "
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    ABSTRACT: A compact silicon-based polarization splitter (PS) is proposed using a three-guide directional coupler composed of a silicon nanowire in the center and two horizontal/vertical hybrid-plasmonic waveguides (HPWs) at outer sides. Utilizing the evanescent coupling, the injected TE/TM modes in the central silicon nanowire can be only coupled to the horizontal/vertical HPWs, leading to the separation of input polarizations. Moreover, to improve the extinction ratio (ER), an S-bend connecting with the vertical HPW is employed. Results show that a coupling length of 6.5 (4.5) μm is achieved at the wavelength of 1.55 μm with ER and insertion loss of ~18.9 (15.2) dB and ~0.44 (0.89) dB for TE (TM) mode, and the bandwidths can cover the entire C-band for both polarizations. In addition, fabrication tolerances to the structural parameters are presented and field evolution through the designed PS is also demonstrated.
    Full-text · Article · Mar 2015 · IEEE Photonics Technology Letters
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    • "For instance, hybrid plasmonic waveguide (HPW), which confines mode within the low index gap between a metal and a high index dielectric, has already been introduced into the design of PBS [12]–[15]. In [12], Chee et al. proposed a PBS based on three-guide structures, where a HPW was used as the middle waveguide to achieve large birefringence , only allowing TM mode to directionally couple to the cross port. The experimental results demonstrate that the coupling length is ∼6.5 μm with extinction ratio (ER) and insertion loss (IL) of 12.3 (13.9) dB and 2.8 (6.0) dB for TE (TM) mode, respectively. "
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    ABSTRACT: A compact polarization beam splitter (PBS) for silicon-based slot waveguides is proposed, where an asymmetrical multimode waveguide (AMW), cut by a right angle at one corner, is employed to efficiently separate the TE and TM modes. With the unique modal properties of the slot waveguides, the input TE mode almost passes through the AMW and enters into the bar port, while the input TM mode forms a mirror image at the cross port due to the self-imaging effect. Tapered waveguide structures and S-bend are incorporated into the PBS for enhancing the performance. Results show that a PBS with an AMW of 2.3 μm in length is achieved, where the extinction ratios are 16.6 and 20.9 dB, respectively, for TE and TM modes, and the insertion losses are 1.37 and 0.81 dB, respectively, at the wavelength of 1.55 μm, and the bandwidths can cover the entire C-band for both polarizations. In addition, fabrication tolerances to the structural parameters are investigated and field evolution along the propagation distance through the designed PBS is also demonstrated.
    Full-text · Article · Dec 2014 · Journal of Lightwave Technology
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    • "For instance, hybrid plasmonic waveguide (HPW), which confines mode within the low index gap between a metal and a high index dielectric, has already been introduced into the design of PBS [12]–[15]. In [12], Chee et al. proposed a PBS based on three-guide structures, where a HPW was used as the middle waveguide to achieve large birefringence , only allowing TM mode to directionally couple to the cross port. The experimental results demonstrate that the coupling length is ∼6.5 μm with extinction ratio (ER) and insertion loss (IL) of 12.3 (13.9) dB and 2.8 (6.0) dB for TE (TM) mode, respectively. "
    [Show abstract] [Hide abstract]
    ABSTRACT: A compact polarization beam splitter (PBS) for silicon-based slot waveguides is proposed, where an asymmetrical multimode waveguide (AMW), cut by a right angle at one corner, is employed to efficiently separate the TE and TM modes. With the unique modal properties of the slot waveguides, the input TE mode almost passes through the AMW and enters into the bar port, while the input TM mode forms a mirror image at the cross port due to the self-imaging effect. Tapered waveguide structures and S-bend are incorporated into the PBS for enhancing the performance. Results show that a PBS with an AMW of 2.3 μm in length is achieved, where the extinction ratios are 16.6 and 20.9 dB, respectively, for TE and TM modes, and the insertion losses are 1.37 and 0.81 dB, respectively, at the wavelength of 1.55 μm, and the bandwidths can cover the entire C-band for both polarizations. In addition, fabrication tolerances to the structural parameters are investigated and field evolution along the propagation distance through the designed PBS is also demonstrated.
    Full-text · Article · Dec 2014 · Journal of Lightwave Technology
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