An integrated-nanophotonics polarization beamsplitter with 2.4 × 2.4 μm2 footprint

Journal name:
Nature Photonics
Volume:
9,
Pages:
378–382
Year published:
DOI:
doi:10.1038/nphoton.2015.80
Received
Accepted
Published online

We have designed, fabricated and characterized an integrated-nanophotonics polarization beamsplitter with a footprint of 2.4 × 2.4 μm2, which is the smallest polarization beamsplitter ever demonstrated. A nonlinear optimization algorithm was used to design the device for λ0 = 1,550 nm. The polarization beamsplitter and the input/output waveguides can be fabricated in a single lithography step. Here, we experimentally show an average transmission efficiency of greater than 70% (peak transmission efficiency of ∼80%) and an extinction ratio greater than 10 dB within a bandwidth of 32 nm. Simulation results indicate that our device is tolerant to fabrication errors of up to ±20 nm in the device thickness. We also designed, fabricated and characterized a mode-converting polarization beamsplitter, which not only separates the two polarization states but also connects one multimode input waveguide to two single-mode output waveguides.

At a glance

Figures

  1. The nanophotonic polarization beamsplitter.
    Figure 1: The nanophotonic polarization beamsplitter.

    a, Geometry of the device. b,c, Simulated steady-state intensity distributions for TE (b) and TM (c) polarized light at the design wavelength of 1,550 nm (Supplementary Movie 1). TE is polarized in-plane and perpendicular to the propagation direction, as illustrated by the green arrows in a, and TM is polarized out-of-plane, as illustrated by red circles in a.

  2. Experiment.
    Figure 2: Experiment.

    a, Scanning electron micrograph of the fabricated device. b, Measurement system set-up.

  3. Experimental and simulated performance of the nanophotonic PBS.
    Figure 3: Experimental and simulated performance of the nanophotonic PBS.

    a,b, Measured and simulated transmission efficiencies (a) and extinction ratios (b) of the PBS for both TE and TM polarization. Measured (expt.) and simulated (sim.) data are shown using solid and dashed lines, respectively. c,d, Simulated transmission efficiencies (c) and extinction ratios (d) as a function of device (silicon) thickness. For all figures, TE and TM polarizations are shown in blue and red, respectively.

  4. Mode-converting PBS.
    Figure 4: Mode-converting PBS.

    a,b, Configuration (a) and scanning electron micrograph (b) of the mode-converting PBS. c,d, Intensity distributions for TE (c) and TM (d) polarized light at 1,550 nm (Supplementary Movie 2).

  5. Experimental and simulated performance of the nanophotonic mode-converting PBS.
    Figure 5: Experimental and simulated performance of the nanophotonic mode-converting PBS.

    a, Simulated and measured transmission efficiencies as a function of wavelength. b, Simulated and measured extinction ratio as a function of wavelength. TE and TM are denoted by blue and red lines, and dashed and solid lines represent the corresponding simulation and experimental efficiencies. c,d, Simulated transmission efficiency (c) and extinction ratio (d) as a function of silicon thickness.

References

  1. Manolatou, C. et al. High density integrated optics. J. Lightw. Technol. 17, 16821692 (1999).
  2. Fukuda, H. et al. Ultrasmall polarization splitter based on silicon wire waveguides. Opt. Express 14, 1240112408 (2006).
  3. Yuan, W. et al. Mode-evolution-based polarization rotator-splitter design via simple fabrication process. Opt. Express 20, 1016310169 (2012).
  4. Watts, M. R., Haus, H. A. & Ippen, E. P. Integrated mode-evolution-based polarization splitter. Opt. Lett. 30, 967969 (2005).
  5. Hong, J. M. et al. Design and fabrication of a significantly shortened multimode interference coupler for polarization splitter application. IEEE Photon. Technol. Lett. 15, 7274 (2003).
  6. Tu, Z. et al. A compact SOI polarization beam splitter based on multimode interference couple. Proc. SPIE, 8307, 830707 (2011).
  7. Dai, D., Wang, Z. & Bowers, J. E. Ultrashort broadband polarization beam splitter based on an asymmetrical directional coupler. Opt. Lett. 36, 25902592 (2011).
  8. Feng, J. & Zhou, Z. Polarization beam splitter using a binary blazed grating coupler. Opt. Lett. 32, 16621664 (2007).
  9. Yue, Y., Zhang, L., Yang, J.-Y., Beausoleil, R. G. & Willner, A. E. Silicon-on-insulator polarization splitter using two horizontally slotted waveguides. Opt. Lett. 35, 13641366 (2010).
  10. Kiyat, I., Aydinli, A. & Dagli, N. A compact silicon-on-insulator polarization splitter. IEEE Photon. Technol. Lett. 17, 100102 (2005).
  11. Liu, T., Zakharian, A. R., Fallahi, M., Moloney, J. V. & Mansuripur, M. Design of a compact photonic-crystal-based polarizing beam splitter. IEEE Photon. Technol. Lett. 17, 14351437 (2005).
  12. Guan, X., Wu, H., Shi, Y., Wosinski, L. & Dai, D. Ultracompact and broadband polarization beam splitter utilizing the evanescent coupling between a hybrid plasmonic waveguide and a silicon nanowire. Opt. Lett. 38, 30053008 (2013).
  13. Sesay, M., Jin, X. & Ouyang, Z. Design of polarization beam splitter based on coupled rods in a square-lattice photonic crystal. J. Opt. Soc. Am. B 30, 20432047 (2013).
  14. Dai, D., Wang, Z., Peters, J. & Bowers, J. E. Compact polarization beam splitter using an asymmetrical Mach–Zehnder interferometer based on silicon-on-insulator waveguides. IEEE Photon. Technol. Lett. 24, 673675 (2012).
  15. Soldano, L. B. et al. Mach–Zehnder interferometer polarization splitter in InGaAsP/InP. IEEE Photon. Technol. Lett. 6, 402405 (1994).
  16. Lu, J. & Vučković, J. Nanophotonic computational design. Opt. Express 21, 1335113367 (2013).
  17. Shen, B., Wang, P., Polson, R. & Menon, R. Integrated metamaterials for efficient and compact free-space-to-waveguide coupling. Opt. Express 22, 2717527182 (2014).
  18. Piggott, A. Y. et al. Inverse design and implementation of a wavelength demultiplexing grating coupler. Sci. Rep. 4, 7210 (2014).
  19. Kim, G., Dominguez-Caballero, J.-A., Lee, H., Friedman, D. J. & Menon, R. Increased photovoltaic power output via diffractive spectrum separation. Phys. Rev. Lett. 110, 123901 (2013).
  20. Shen, B., Wang, P., Polson, R. & Menon, R. Ultra-high-efficiency metamaterial polarizer. Optica 1, 356360 (2014).
  21. Wang, P. & Menon, R. Optimization of generalized dielectric nanostructures for enhanced light trapping in thin-film photovoltaics via boosting the local density of optical states. Opt. Express 22, A99A110 (2014).
  22. Shen, B., Wang, P. & Menon, R. Optimization and analysis of 3D nanostructures for power-density enhancement in ultra-thin photovoltaics under oblique illumination. Opt. Express 22, A311A319 (2014).
  23. Kim, G. & Menon, R. An ultra-small three dimensional computational microscope. Appl. Phys. Lett. 105, 061114 (2014).
  24. Oskooi, A. F. et al. MEEP: a flexible free-software package for electromagnetic simulations by the FDTD method. Comput. Phys. Commun. 181, 687702 (2010).
  25. Liu, L., Ding, Y., Yvind, K. & Hvam, J. M. Efficient and compact TE–TM polarization converter built on silicon-on-insulator platform with a simple fabrication process. Opt. Lett. 36, 10591061 (2011).
  26. Bogaerts, W. et al. Basic structures for photonic integrated circuits in silicon-on-insulator. Opt. Express 12, 15831591 (2004).

Download references

Author information

Affiliations

  1. Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112, USA

    • Bing Shen,
    • Peng Wang &
    • Rajesh Menon
  2. Utah Nanofabrication Facility, University of Utah, Salt Lake City, Utah 84112, USA

    • Randy Polson

Contributions

B.S., P.W. and R.M. conceived and designed the experiments. B.S., P.W. and R.P. contributed materials/analysis tools. B.S. performed the experiments. B.S., R.P. and R.M. analysed the data. B.S., R.P. and R.M. wrote the paper.

Competing financial interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to:

Author details

Supplementary information

PDF files

  1. Supplementary information (2,097 KB)

    Supplementary information

Movies

  1. Supplementary movie 1 (3,564 KB)

    Supplementary information

  2. Supplementary movie 2 (1,378 KB)

    Supplementary information

Additional data