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Efficient colour splitters for high-pixel-density image sensors

Nature Photonics volume 7, pages 240–246 (2013)Cite this article

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Abstract

When the pixel size of image sensors shrinks to the wavelength of light, this results in low signal levels for a given photon flux per pixel as a result of scaling laws. Because many image sensors require colour filters, it becomes crucial for small-pixel sensors to have an efficient filtering method that can capture all incident photons without absorbing them. Here, we propose a new method to split colours by using a microscale plate-like structure with a transparent medium that has a higher refractive index than the surrounding material. We experimentally demonstrate that this principle of colour splitting based on near-field deflection can generate colour images with minimal signal loss. From comparisons of the sum of the total integrated values for the colour channels, we confirm the amount of light received is 1.85 times that of the conventional colour filter method of the Bayer array, while maintaining the same level of resolution.

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Figure 1: Operational principle of a symmetric deflector.
Figure 2: Operational principle of an asymmetric deflector.
Figure 3: Spectra from symmetric and asymmetric deflectors.
Figure 4: The two-deflector method and demonstration of colour splitting.
Figure 5: Cross-sectional SEM images of a conventional CCD and MiCS-IS.
Figure 6: Imaging characteristics of a MiCS-IS.

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Acknowledgements

The authors thank K. Yonemoto for useful discussions about device design and fabrication.

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Authors and Affiliations

  1. Device Solutions Center, Panasonic Corporation, 3-1-1 Yagumo-nakamachi, Moriguchi City, Osaka, 570-8501, Japan

    Seiji Nishiwaki, Tatsuya Nakamura & Masa-aki Suzuki

  2. Cloud Solutions Center, Panasonic Corporation, 1006 Ôaza-Kadoma, Kadoma City, Osaka, 571-8501, Japan

    Masao Hiramoto

  3. Image Sensor Business Unit, Semiconductor Business Group, Industrial Devices Company, Panasonic Corporation, 1 Kôtari-yakemachi, Nagaokakyô City, Kyoto, 617-8520, Japan

    Toshiya Fujii

Authors
  1. Seiji Nishiwaki
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  2. Tatsuya Nakamura
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  5. Masa-aki Suzuki
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Contributions

S.N. devised the concept and analytical method. T.N. assisted with fabrication and the experiments. M.H. supplied the concept of the two-deflector method and contributed to imaging with T.F. Overall supervision was provided by M.S.

Corresponding author

Correspondence to Seiji Nishiwaki.

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The authors declare no competing financial interests.

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Nishiwaki, S., Nakamura, T., Hiramoto, M. et al. Efficient colour splitters for high-pixel-density image sensors. Nature Photon 7, 240–246 (2013). https://doi.org/10.1038/nphoton.2012.345

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