Interleaved Subwavelength Gratings Strip Waveguide Based TM Pass Polarizer on SOI Platform

Abstract

We report on an ultra-compact, low loss and broadband TM-pass polarizer, which is constructed by two interleaved subwavelength-gratings (SWGs) waveguides inserted in the center of the strip waveguide on a silicon-on-insulator (SOI) platform. The device structure is optimally engineered to support Bloch mode for fundamental TM polarization only. Therefore, the TM mode transmits along the strip waveguide with rather low propagation loss while the TE mode is completely reflected by the embedded SWGs waveguides. Simulation results show that an efficient and ultra-compact TM-pass polarizer of 5.2 μm in length is realized with extinction ratio (ER) of 31.63 dB and insertion loss (IL) of 0.18 dB at the operating wavelength of 1550 nm. The operation bandwidth for ER over 20 dB and IL below 0.32 dB is 155 nm (from 1465 to 1620 nm). By increasing the period number, the ER performance and bandwidth can be further improved. Furthermore, the fabrication of the present polarizer only requires mono-lithography and single etch process, which will greatly reduce the fabrication difficulty.

Ultra-Broadband Polarization Beam Splitter Based on Cascaded Mach-Zehnder Interferometers Assisted by Effectively Anisotropic Structures

“…S2 is the width of the SWGs, W2 is the width of strip waveguide, ρi, Λi are the duty cycle of silicon and period of the i-th (i=2,3) SWGs and the total period is Λtotal=Λ2+Λ3. By optimizing these parameters, this structure can support Bloch mode for the TM polarization only [28]. Hence, the TM polarization can travel along the strip waveguide with rather low loss while the TE polarization would be completely reflected by the embedded SWG structure due to the Bragg reflection.…”

An Ultra-Broadband Design of TM-Pass/TE-Stop Polarizer Based on Multistage Bragg Gratings

“…In this case, there is a great demand to produce a polarization management device to perform polarization states manipulation in PICs. To date, a number of device structures have been reported to perform various polarization control functions, including polarization beam splitters (PBS) [2][3][4], polarization splitter-rotators (PSR) [5][6][7], and polarizers [8][9][10]. Theoretically, the PBS and PSR require restrict phase matching conditions to realize splitting operations so their structural geometries have to be carefully controlled in design and fabrication.…”

“…The reflection-based polarizer provides a relatively good trade-off between the device footprint and loss. Typically, it reflects the unwanted polarization state with Bragg gratings at a reasonable length of slightly less than 10 µm [10,17]. Additionally, the achieved IL are always less than 0.5 dB over the entire operating wavelength band.…”

Ultralow Loss and High Extinction Ratio TM-Pass Polarizer in Silicon Photonics

“…Several SOI TM-pass polarizers have been proposed and experimentally demonstrated in the literature. They are based on one-dimensional or two-dimensional photonic crystal waveguides [13][14][15], a silicon strip waveguide embedding a graphene/Si3N4/graphene multilayer [16], photonic/plasmonic hybrid grating waveguides [17][18][19], a silicon wire coupled to a highly doped silicon waveguide [20], a silicon wire with a VO2 film on the vertical sidewalls [21], subwavelength grating waveguides [22][23][24][25], a waveguiding structure with two tapered waveguides sandwiching a narrow waveguide only supporting TM mode propagation [25], plasmonic bends [26], and hyperuniform disordered structures [27][28][29][30]. The features of these components, in terms of length, insertion loss (IL) and extinction ratio (ER), are summarized in Table I.…”

“…The achieved ERs are very good, with a record exceeding 45 dB, while the IL is typically not very low, with values < 0.5 dB only in the devices reported in [19,[24][25]. Finally, the length of the silicon TM-pass polarizers in the state-of-the-art is very short, typically ranging from a few μm to a few tens of μm.…”