Photonics Research, 2020, 8 (7): 07001197, Published Online: Jun. 29, 2020
Low-loss hybrid plasmonic TM-pass polarizer using polarization-dependent mode conversion Download: 577次
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Fig. 1. (a) Schematic of the proposed TM-pass polarizer. Inset: (i) Compact strip-to-slot mode convertor; (ii) HPSW active region; (iii) cross-section of the HPSW. As an example, the widths of “rails” (W si ) and slot (W slot ) in the HPSW are chosen as 240 and 180 nm, while the width of metal layer (W m ) is chosen as 300 nm. Besides, the inner radius (R 1 ) and outer radius (R 2 ) of the metal “wing” in ARS are set as 500 and 800 nm in our design, respectively. Under this structural configuration, the dielectric slot waveguide supports four eigenmodes: TE 0 slot , TE 1 slot , TM 0 slot , and TM 1 slot . (b) The polarization-dependent mode-conversion process in the proposed device.
Fig. 2. Transverse magnetic-field profile of (a) EM 2 , (b) EM 4 , and (c) EM 5 . Black arrows represent the electrical field directions. Corresponding power coupling ratios of (d) EM 2 , (e) EM 4 , and (f) EM 5 with sweeping Gap and H m when TE 0 slot is injected into the HPSW. The mode profiles for TE 0 slot , EM 2 , EM 4 , and EM 5 are given under the dimension that W si = 240 nm , W slot = 180 nm , W m = 300 nm , Gap = 45 nm , and h Au = 45 nm .
Fig. 3. Transverse magnetic-field profile of (a) EM 1 , (b) EM 3 , and (c) EM 6 . Black arrows represent the electrical field directions. Corresponding power coupling ratios of (d) EM 1 , (e) EM 3 , and (f) EM 6 with sweeping Gap and H m when TM 0 slot is injected into the HPSW. The mode profiles for TM 0 slot , EM 1 , EM 3 , and EM 6 are given under the dimension that W si = 240 nm , W slot = 180 nm , W m = 300 nm , Gap = 45 nm , and h Au = 45 nm .
Fig. 4. (a) Mode overlap ratio after taking logarithm between the mode field on the termination facet of MMI section and TE 0 slot in the output dielectric slot waveguide. (b) Corresponding L m with Gap and H m varied. (c) Comparison between the mode overlap ratio with and without ARS.
Fig. 5. Insertion loss of the strip-to-slot mode convertor (IL c ) varied with respect to W t (for TM 0 incidence). Inset: The transverse magnetic field evolution in the proposed strip-to-slot mode convertor and its schematic diagram of structural parameters.
Fig. 6. Electric-field evolution with the corresponding (b), (e) E x and (c), (f) H x component in the proposed TM-pass polarizer for (a) TE and (d) TM fundamental input. The operation wavelength is 1550 nm, and the refractive indices for gold, SiO 2 , and Si are 0.238 + 11.263 i [32], 1.444, and 3.478, respectively. Besides, the minimum mesh of 5 nm in x , y , and z directions is set to obtain accurate and stable results.
Ruixuan Chen, Bowen Bai, Zhiping Zhou. Low-loss hybrid plasmonic TM-pass polarizer using polarization-dependent mode conversion[J]. Photonics Research, 2020, 8(7): 07001197.