Design and simulation of a compact and ultra-wideband polarization beam splitter based on sub-wavelength grating multimode interference coupler (original) (raw)
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IEEE Photonics Journal
We propose and experimentally demonstrate a broadband polarization beam splitter on the silicon-on-insulator platform using the concept of multi-mode interference. The angle between the input waveguide and the multi-mode interferometer (MMI) was optimized in order to extract the images corresponding to the fundamental transverse electric (TE) and transverse magnetic (TM) polarizations from a single, compact MMI. By changing the direction of propagation, the input angle enabled the addition of a parallelepiped to facilitate exclusively TM collection above the MMI, therefore eliminating the need to cascade successive MMIs. The MMI was tapered to improve coupling at the ports. The design allowed for a compact geometry with a length of 67.5 μm and width of 4 μm, while maintaining a feature size comparable to the waveguide width. The design was experimentally characterized over 72 parameter variations including input angle, output TM and TE port positions, and bend radius of the output TE waveguide. The performance was consistent over the 100 nm wavelength range of 1500-1600 nm, with an average insertion loss of 2 dB. The device maintained an extinction ratio of at least 13.96 dB and 11.45 dB in the C-band for the TE and TM polarizations respectively.
Optics Letters, 2018
We demonstrate an integrated polarization beam splitter (PBS) of a simple and compact device geometry with high polarization extinction ratios (PERs). A silicon PBS based on a three-waveguide directional coupler is numerically simulated for optimum device parameters, and fabricated experimentally. The measured PER values of the fabricated PBSs are 40.74 dB and 39.01 dB for transverse electric and transverse magnetic modes, respectively, and their corresponding insertion losses are 0.35 dB on average for a coupler length of about 29.4 μm.
Numerical Analysis and Optimization of a Multi-Mode Interference Based Polarization Beam Splitter
2017
The progression toward smaller and faster photonic circuits has led to the development of nanophotonic platforms capable of compacting many devices onto an integrated chip. These devices, as well as the input and output grating couplers, are sometimes polarization dependent, which allows for a preferential treatment of different polarizations within the same circuit, especially since the waveguides are capable of supporting both transverse electric (TE) and transverse magnetic (TM) polarizations with manageable crosstalk. This introduces the growing need for reliable devices that can perform polarization conversion or rotation, and splitting or filtering, in order to test nanophotonic circuits that incorporate polarization diversity. This paper characterizes the response of a fabrication tolerant multimode interferometer (MMI) based polarization beam splitter (PBS) for the C-band wavelength range, over different waveguide input/output configurations. It is found that the position of...
Passive broadband silicon-on-insulator polarization splitter
Optics Letters, 2007
We present the implementation of a novel wavelength independent polarization splitter on a silicon-oninsulator platform. The waveguide splitter is based on a zero-order arrayed waveguide grating (AWG) configuration. The splitting function is realized by employing cladding stress-induced birefringence. The device demonstrated a TE to TM splitting ratio better than −15 dB over a 20 nm tuning range centered around = 1550 nm and better than −10 dB over our entire accessible wavelength range from = 1465 nm to 1580 nm. The highest splitting extinction ratio achieved was −20 dB. To our knowledge, this is the first reported passive broadband polarization splitter based on AWG.
Grating coupler serving as polarization beam splitter in silicon-on-insulator platform
We present in this work a one-dimensional grating coupler that serves as polarization splitter to couple the light from a single-mode optical fiber to single-mode integrated silicon waveguides and separate both orthogonal polarization states at the same time. The reported structure has been fabricated using standard complementary metal-oxide-semiconductor technology process and exhibits good coupling efficiency around-4 dB for both polarizations and high extinction ratios around 30 dB near the telecommunication wavelength 1550 nm at both outputs. The simulation and measurement results show the coupling and polarization splitting effect in a wide wavelength range and are in good agreement.
A compact bi-wavelength polarization splitting grating coupler fabricated in a 220 nm SOI platform
Optics Express, 2013
We experimentally demonstrate a polarization splitting grating coupler that is operational near 1310 nm and 1550 nm in a silicon-oninsulator platform, using the same fiber angle for both wavelength bands. At 1550 nm, the device has an insertion loss of 7.1 dB and a 1.5-dB transmission window of 35 nm. At 1310 nm, the insertion loss and 1.5-dB transmission window are 8.2 dB and 18 nm, respectively. Polarization isolation at 1550 nm is 24 dB. This is the first experimental demonstration of a bi-wavelength polarization-splitting grating coupler.
Optics letters, 2017
We report on the design and experimental demonstration of a broadband silicon polarization beam splitter (PBS) with a high extinction ratio (ER)≥30 dB. This was achieved using triple-bent-waveguide directional coupling in a single PBS, and cascaded PBS topology. For the single PBS, the bandwidths for an ER≥30 dB are 20 nm for the quasi-TE mode, and 70 nm for the quasi-TM mode when a broadband light source (1520-1610 nm) was employed. The insertion loss (IL) varies from 0.2 to 1 dB for the quasi-TE mode and 0.2-2 dB for the quasi-TM mode. The cascaded PBS improved the bandwidth of the quasi-TE mode for an ER≥30 dB to 90 nm, with a low IL of 0.2-2 dB. To the best of our knowledge, our PBS system is one of the best broadband PBSs with an ER as high as ∼42 dB and a low IL below 1 dB around the central wavelength, and experimentally demonstrated using edge-coupling.
Novel ultra-short and ultra-broadband polarization beam splitter based on a bent directional coupler
Optics express, 2011
A novel ultra-short polarization beam splitter (PBS) based on a bent directional coupler is proposed by utilizing the evanescent coupling between two bent optical waveguides with different core widths. For the bent directional coupler, there is a significant phase-mismatch for TE polarization while the phase-matching condition is satisfied for TM polarization. Therefore, the TM polarized light can be coupled from the narrow input waveguide to the adjacent wide waveguide while the TE polarization goes through the coupling region without significant coupling. An ultra-short (<10 μm-long) PBS is designed based on silicon-on-insulator nanowires and the length of the bent coupling region is as small as 4.5 μm while the gap width is chosen as 200 nm (large enough to simplify the fabrication). Numerical simulations show that the present PBS has a good fabrication tolerance for the variation of the waveguide width (more than ± 60 nm) and a very broad band (~200 nm) for an extinction rati...
Optics Express, 2013
We propose and analyze a compact polarizing beam splitter (PBS) based on a metal-insulator-metal (MIM) structure inserted into a multimode interference coupler (MMI). Owing to the MIM structure, the TE polarized state is reflected by the cutoff condition while the TM polarized state is transmitted by the surface plasmon polariton, and the two polarized states can thus be separated. In this paper, the dependence of the reflected TE and transmitted TM field intensities on the MIM length and the gap thickness has been studied systematically. The proposed PBS structure, with a total size of 4 × 0.7 × 44 µm 3 is designed with MIM length, gap thickness, and metal thickness of 0.6 µm, 0.5 µm, and 0.05 µm, respectively. In the designed PBS, the transmittance for the TM polarized light, reflectance for the TE polarized light, extinction ratio, and insertion losses of the TE and TM modes are obtained using a 3D finite-difference time-domain method to be 0.9, 0.88, 12.55 dB, and 1.1 dB and 0.9 dB, respectively. The designed PBS has a much shorter length, 44 µm, compared to previous PBS devices.