The University of Southampton
University of Southampton Institutional Repository

Light-induced structural phase transition in confining gallium and associated gigantic optical nonlinearity

Light-induced structural phase transition in confining gallium and associated gigantic optical nonlinearity
Light-induced structural phase transition in confining gallium and associated gigantic optical nonlinearity
We discovered a new type of light-induced structural surface assisted phase transition, which occurs in the vicinity, but below the bulk melting point (29.6C) of metallic alpha-gallium interfacing with a dielectric such as silica or glass. The transition is not a thermal effect, but is provoked by an optical destabilisation of the covalent bonding structure of alpha-gallium. The transition is to a more reflective, metastable 'metallic' like phase. The light penetrates only about 25 nm in gallium, with only several tens of atomic layers of the metal being affected by the phase transition. This is enough to change the interface reflectivity significantly, on several tens of percent. The light-induced phase has not been precisely identified yet, but several metastable phases of crystalline gallium and quasi liquid state are potential candidates. The phase transition may be stimulated with light of a very low intensity and wavelength spanning from 0.5 to 1.6µm. The thickness of the metallized layer and its reflectivity increase with the light intensity and the phase transition is fully reversible if the light is withdrawn. The transitions between the phases occur very fast, on nanosecond - microsecond time scales, depending on the sample temperature. The recovery time of the alpha-phase critically increases when the interface temperature approaches the material's melting point, as it would be appropriate for a second order phase transition. We also observed a self-oscillatory reaction on optical excitation of confining gallium layers of only a few nanometres thick. As the intensity of light necessary to stimulate the phase transition is very low, and only a few milliwatts of laser lower is required to observe it, the discovered metallic-dielectric structure has immense potential for waveguide photonic applications and optical data processing and storage.
Albanis, V.
c5691c2e-71bc-4ca2-8d65-c0396fa228c2
Dhanjal, S.
a3f4fa8d-654f-4162-bd38-67c9b2d2f136
Petropoulos, P.
522b02cc-9f3f-468e-bca5-e9f58cc9cad7
Richardson, D.J.
ebfe1ff9-d0c2-4e52-b7ae-c1b13bccdef3
Zheludev, N.
32fb6af7-97e4-4d11-bca6-805745e40cc6
Emelyanov, V.
4a71b24f-e7a1-4996-8c44-2a4f666dfc76
Albanis, V.
c5691c2e-71bc-4ca2-8d65-c0396fa228c2
Dhanjal, S.
a3f4fa8d-654f-4162-bd38-67c9b2d2f136
Petropoulos, P.
522b02cc-9f3f-468e-bca5-e9f58cc9cad7
Richardson, D.J.
ebfe1ff9-d0c2-4e52-b7ae-c1b13bccdef3
Zheludev, N.
32fb6af7-97e4-4d11-bca6-805745e40cc6
Emelyanov, V.
4a71b24f-e7a1-4996-8c44-2a4f666dfc76

Albanis, V., Dhanjal, S., Petropoulos, P., Richardson, D.J., Zheludev, N. and Emelyanov, V. (1998) Light-induced structural phase transition in confining gallium and associated gigantic optical nonlinearity. MRS Fall Meeting, United States. 30 Nov - 04 Dec 1998.

Record type: Conference or Workshop Item (Paper)

Abstract

We discovered a new type of light-induced structural surface assisted phase transition, which occurs in the vicinity, but below the bulk melting point (29.6C) of metallic alpha-gallium interfacing with a dielectric such as silica or glass. The transition is not a thermal effect, but is provoked by an optical destabilisation of the covalent bonding structure of alpha-gallium. The transition is to a more reflective, metastable 'metallic' like phase. The light penetrates only about 25 nm in gallium, with only several tens of atomic layers of the metal being affected by the phase transition. This is enough to change the interface reflectivity significantly, on several tens of percent. The light-induced phase has not been precisely identified yet, but several metastable phases of crystalline gallium and quasi liquid state are potential candidates. The phase transition may be stimulated with light of a very low intensity and wavelength spanning from 0.5 to 1.6µm. The thickness of the metallized layer and its reflectivity increase with the light intensity and the phase transition is fully reversible if the light is withdrawn. The transitions between the phases occur very fast, on nanosecond - microsecond time scales, depending on the sample temperature. The recovery time of the alpha-phase critically increases when the interface temperature approaches the material's melting point, as it would be appropriate for a second order phase transition. We also observed a self-oscillatory reaction on optical excitation of confining gallium layers of only a few nanometres thick. As the intensity of light necessary to stimulate the phase transition is very low, and only a few milliwatts of laser lower is required to observe it, the discovered metallic-dielectric structure has immense potential for waveguide photonic applications and optical data processing and storage.

Full text not available from this repository.

More information

Published date: 1998
Additional Information: W7.19
Venue - Dates: MRS Fall Meeting, United States, 1998-11-30 - 1998-12-04

Identifiers

Local EPrints ID: 76602
URI: https://eprints.soton.ac.uk/id/eprint/76602
PURE UUID: 8949de50-c4af-46ae-9af9-a7c435544adc
ORCID for P. Petropoulos: ORCID iD orcid.org/0000-0002-1576-8034
ORCID for D.J. Richardson: ORCID iD orcid.org/0000-0002-7751-1058
ORCID for N. Zheludev: ORCID iD orcid.org/0000-0002-1013-6636

Catalogue record

Date deposited: 11 Mar 2010
Last modified: 06 Mar 2019 01:37

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×