We report on a wavelength-selective, polarization-rotating filter using a partially etched asymmetric Bragg grating on a compact single-mode, silicon-on-insulator (SOI) strip waveguide. The asymmetric Bragg grating rotates and reflects the fundamental transverse electric (TE) and transverse magnetic (TM) modes at selected wavelengths. Our device offers wavelength-selective, polarization-rotating reflection at its reflection port and wavelength-selective, polarization-independent notch filtering at its through port. The device is fabricated using a CMOS-compatible process with 193 nm-deep ultraviolet lithography on an SOI platform. We present results for a 294.4 μm long device that has a 3 dB bandwidth of 2.63 nm and a low-excess loss of less than 1 dB. This device also has a maximum polarization-extinction-ratio of greater than 27 dB.
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http://dx.doi.org/10.1364/OL.40.005578 | DOI Listing |
Light Sci Appl
June 2023
State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou, 510275, China.
With the distinct advantages of high resolution, small pixel size, and multi-level pure phase modulation, liquid crystal on silicon (LCoS) devices afford precise and reconfigurable spatial light modulation that enables versatile applications ranging from micro-displays to optical communications. However, LCoS devices suffer from a long-standing problem of polarization-dependent response in that they only perform phase modulation on one linear polarization of light, and polarization-independent phase modulation-essential for most applications-have had to use complicated polarization-diversity optics. We propose and demonstrate, for the first time, an LCoS device that directly achieves high-performance polarization-independent phase modulation at telecommunication wavelengths with 4K resolution and beyond by embedding a polarization-rotating metasurface between the LCoS backplane and the liquid crystal phase-modulating layer.
View Article and Find Full Text PDFWe propose a waveguide frontend with integrated polarization diversity optics for a wavelength selective switch (WSS) array with a liquid crystal on silicon switching engine to simplify the free space optics configuration and the alignment process in optical modules. The polarization diversity function is realized by the integration of a waveguide-type polarization beam splitter and a polarization rotating half-wave plate in a beam launcher using silica-based planar lightwave circuit technology. We confirmed experimentally the feasibility of using our proposed waveguide frontend in a two-in-one 1 × 20 WSS.
View Article and Find Full Text PDFWe report on a wavelength-selective, polarization-rotating filter using a partially etched asymmetric Bragg grating on a compact single-mode, silicon-on-insulator (SOI) strip waveguide. The asymmetric Bragg grating rotates and reflects the fundamental transverse electric (TE) and transverse magnetic (TM) modes at selected wavelengths. Our device offers wavelength-selective, polarization-rotating reflection at its reflection port and wavelength-selective, polarization-independent notch filtering at its through port.
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