Nanophotonic computational design - Stanford University

Fig. 27. Analysis of fabrication-error on the performance of the broadband wavelengthsplitter. Original central wavelengths are shown to hold greater than 70% efficiency, inspite of up to 8 nm of over- or under-etch error.

Fig. 28. Comparison of under-etched, as-designed, and over-etched structures. Differencesare subtle since the pixel size is 40 nm and the fabrication error is 8 nm.

5. Conclusion

We have developed and implemented a method to design linear nanophotonic structures whichare fully three-dimensional and multi-modal, have very compact footprints, exhibit high effi-ciency, and are manufacturable. We demonstrate this capability by designing various nanopho-tonic mode converters, splitters, hubs, and fiber couplers. Critically, many, if not all, of thesedevices have never been demonstrated before and cannot be designed by hand. In contrast,our method allows user to easily design such devices by virtue of our design-by-specificationscheme.

In addition, we demonstrate the design of a broadband device which is strongly robust towavelength and temperature shift, as well as fabrication error. We show that such a device hasstable operating wavelengths over temperature shifts as large as 905 K, or over-/under-etchingerror of up to 8 nm. We suggest, based on this design, that wavelength tolerance may be agood heuristic to the design of temperature and fabrication-error tolerant nanophotonic devices.

Acknowledgments

This work has been supported by the AFOSR MURI for Complex and Robust On-chipNanophotonics (Dr. Gernot Pomrenke), grant number FA9550-09-1-0704.

(C) 2013 OSA 3 June 2013 | Vol. 21, No. 11 | DOI:10.1364/OE.21.013351 | OPTICS EXPRESS 13367