Silicon-on-insulator polarization splitting and rotating device for polarization diversity circuits

School for Information and Optoelectronic Science and Engineering, South China Normal University, 510006 Guangzhou, China.
Optics Express (Impact Factor: 3.49). 06/2011; 19(13):12646-51. DOI: 10.1364/OE.19.012646
Source: PubMed


A compact and efficient polarization splitting and rotating device built on the silicon-on-insulator platform is introduced, which can be readily used for the interface section of a polarization diversity circuit. The device is compact, with a total length of a few tens of microns. It is also simple, consisting of only two parallel silicon-on-insulator wire waveguides with different widths, and thus requiring no additional and nonstandard fabrication steps. A total insertion loss of -0.6 dB and an extinction ratio of 12 dB have been obtained experimentally in the whole C-band.

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Available from: Yunhong Ding, Oct 27, 2014
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    • "However, in this case the input and output silicon waveguides have different thicknesses imposing a serious restriction when integrated in a more complex device. Alternatively, an asymmetrical directional coupler has been demonstrated which only requires one lithography and etching step[4]and that can also be used for splitting the polarization[5],[6]. However, longer lengths are required and the vertical symmetry of the coupler must also be broken by using a different top-cladding material from that of the buffer layer which again would impose restrictions for its integration. "
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    ABSTRACT: A polarization rotator in silicon-on-insulator technology based on breaking the symmetry of the waveguide cross section is reported. The 25- $mu{rm m}$-long device is designed to be integrated with standard grating couplers without the need for extra fabrication steps. Hence, fabrication is carried out by a 2-etch-step complementary metal–oxide–semiconductor compatible process using 193-nm deep ultraviolet lithography. A polarization conversion efficiency of more than ${-}{rm 0.85}~{rm dB}$ with insertion losses ranging from ${-}{1}$ to ${-}{rm 2.5}~{rm dB}$ over a wavelength range of 30 nm is demonstrated.
    Preview · Article · Nov 2012 · IEEE Photonics Technology Letters
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    • "However, this usually requires complicated fabrication steps and increases the footprint of the device. An elegant and simple solution for a polarization rotator is using an asymmetrical directional coupler similar as the one presented in [2] and [6], which is based on the existence of hybrid supermodes [7]. In this letter we go one step further and use this polarization rotating directional coupler in the coupling section of the microring resonator to excite the fundamental quasi-TM mode in the ring. "
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    ABSTRACT: We propose a novel microring resonator concept that uses a polarization rotating asymmetrical directional coupler. The quasi-transverse electric polarized mode in the bus waveguide is used to excite the quasi-transverse magnetic (TM) polarized mode in the microring. This enables the realization of microrings with a high quality factor due to the lower scattering loss of the quasi-TM polarized mode. We demonstrate the operation principle with two all-pass microrings with radius 30 $\mu{\rm m}$, working in the critically coupled regime with a quality factor of 31 000 and in the under-coupled regime with a quality factor of 125 000.
    Preview · Article · Jul 2012 · IEEE Photonics Technology Letters
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    • "By slowly changing the waveguide geometry to mimic a 90˚waveguide twist, the polarization state of light in the waveguide will also undergo a 90˚rotation. Unlike devices presented in [10], mode evolution does not rely on phase matching effects and offers broadband polarization rotation [11]. Additionally, it has been shown to work for a variety of waveguide dimensions [7] [9], meaning it is not sensitive to small fabrication errors. "
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    ABSTRACT: A compact and high extinction SOI polarization rotator is fabricated and characterized. For TM to TE rotation, a device 37.5μm in length is demonstrated to have a polarization extinction ratio between 17.8-26dB from 1525nm to 1570nm.
    Full-text · Article · May 2012
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