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Large-scale nanophotonic phased array

Abstract

Electromagnetic phased arrays at radio frequencies are well known and have enabled applications ranging from communications to radar, broadcasting and astronomy1. The ability to generate arbitrary radiation patterns with large-scale phased arrays has long been pursued. Although it is extremely expensive and cumbersome to deploy large-scale radiofrequency phased arrays2, optical phased arrays have a unique advantage in that the much shorter optical wavelength holds promise for large-scale integration3. However, the short optical wavelength also imposes stringent requirements on fabrication. As a consequence, although optical phased arrays have been studied with various platforms4,5,6,7,8 and recently with chip-scale nanophotonics9,10,11,12, all of the demonstrations so far are restricted to one-dimensional or small-scale two-dimensional arrays. Here we report the demonstration of a large-scale two-dimensional nanophotonic phased array (NPA), in which 64 × 64 (4,096) optical nanoantennas are densely integrated on a silicon chip within a footprint of 576 μm × 576 μm with all of the nanoantennas precisely balanced in power and aligned in phase to generate a designed, sophisticated radiation pattern in the far field. We also show that active phase tunability can be realized in the proposed NPA by demonstrating dynamic beam steering and shaping with an 8 × 8 array. This work demonstrates that a robust design, together with state-of-the-art complementary metal-oxide–semiconductor technology, allows large-scale NPAs to be implemented on compact and inexpensive nanophotonic chips. In turn, this enables arbitrary radiation pattern generation using NPAs and therefore extends the functionalities of phased arrays beyond conventional beam focusing and steering, opening up possibilities for large-scale deployment in applications such as communication, laser detection and ranging, three-dimensional holography and biomedical sciences, to name just a few.

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Figure 1: The NPA system.
Figure 2: Device and system simulations.
Figure 3: Experimental results.
Figure 4: Tunable phased array.

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Acknowledgements

We thank K. Shtyrkova and J. S. Orcutt for help with the initial measurement setup, and also APIC Corporation. This work was supported by the Defense Advanced Research Projects Agency (DARPA) of the United States under the E-PHI and SWEEPER projects, grant no. HR0011-12-2-0007. J.S. acknowledges support from DARPA POEM award HR0011-11-C-0100.

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Authors and Affiliations

Authors

Contributions

J.S. and M.R.W. conceived the idea of the project. J.S. simulated and designed the devices and the phased array system, laid out the mask and performed the experimental characterizations and analysis. E.T. helped with the NPA system simulation algorithm. A.Y. contributed to the element antenna simulation. E.H. coordinated the mask. J.S. and M.R.W. wrote the paper. M.R.W. supervised the project. All authors commented on the manuscript.

Corresponding author

Correspondence to Michael R. Watts.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Figures 1-4 and Supplementary Discussions, which provide additional information to the main text. These include: the method used for uniform power distribution and optical phase manipulation in each unit cell (Section S.1, Figure S1); the antenna element design (Section S.2, Figure S2); phased array system simulation algorithm (Section S.3, Figure S3) and phase error tolerance of the phased array (Section S.4, Figure S4). (PDF 3179 kb)

Active Tuning of an 8x8 Nanophotonic Phased Array

This video shows the dynamic pattern generation by actively tuning the phase in the active nanophotonic phased array. (MP4 2516 kb)

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Sun, J., Timurdogan, E., Yaacobi, A. et al. Large-scale nanophotonic phased array. Nature 493, 195–199 (2013). https://doi.org/10.1038/nature11727

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