Coherent all-optical signal processing using fibre-optic metadevices

Abstract

This Thesis merges the physics of metamaterials with optical fibre technology in order to demonstrate low-power, high-bandwidth signal processing applications. Control over optical absorption using linear coherent interactions of light beams with metasurfaces of deeply subwavelength thickness offers a range of novel opportunities. Here I report on:

♦ The first demonstration of a fibre-optic metadevice for coherent all-optical signal processing. The fibre metamaterial has been integrated and packaged resulting in a device that is compatible with standard fibre-optics components.

♦ All-optical signal switching, effective nonlinearity and logical functions XOR, NOT and AND performed within a coherent fibre network at wavelengths between 1530 and 1565 nm. The metadevice has been tested at up to 40 Gbit/s with energy consumption as low as 2.5 fJ/bit.

♦ Dark pulse generation, selective transmission/absorption of 1 ps pulses and all-optical pulse shaping in the telecommunications C-band with 1 THz bandwidth in-fibre.
♦ The first demonstration of a fibre-optic plasmonic/metamaterial device for data security applications. I introduced the concept of coherent cryptography, an optical layer secure communication protocol that does not rely on nonlinear optical processes but instead uses energy redistribution of coherent optical waves interacting on a metamaterial absorber. I demonstrated different types of encryption modes and reported a scheme providing perfect secrecy.
♦ Nonlinear control of coherent absorption in a nonlinear fibre network containing a metamaterial absorber. I exploited power-dependent phase retardation arising from the Kerr effect for all-optical noise suppression, power-limiting, pulse restoration, pulse splitting and signal transfer between carrier wavelengths.
In addition, I have developed and fabricated fibre metadevices, which have enabled:
♦ The first demonstration of coherent perfect absorption and transmission for a single photons in a stabilized quantum fibre network by collaborators.
To conclude, this Thesis investigates all-optical solutions provided by plasmonic metamaterials for coherent signal processing within fibre networks. The above proof-of-principle demonstrations show the appropriateness of such metasurfaces for fibre integration and illustrate application opportunities ranging from all-optical switching and pulse shaping to optical encoding and stabilization of fibre-optic classical and quantum information networks.

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Identifiers

ORCID for Angelos Xomalis: orcid.org/0000-0001-8406-9571

ORCID for Nikolai Zheludev: orcid.org/0000-0002-1013-6636

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