Photo-induced reduction of graphene oxide coating on optical waveguide and consequent optical intermodulation

• Published in: Scientific reports Vol. 6; no. 1; p. 23813
• Main Authors: Chong, W. Y., Lim, W. H., Yap, Y. K., Lai, C. K., De La Rue, R. M., Ahmad, H.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2016; Nature Publishing Group
• Subjects: 639/624/1111; 639/624/399/918/1054; Absorption; Humanities and Social Sciences; Light; Light effects; multidisciplinary; Polymers; Science; Temperature effects
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep23813

Increased absorption of transverse-magnetic (TM) - polarised light by a graphene-oxide (GO) coated polymer waveguide has been observed in the presence of transverse-electric (TE) - polarised light. The GO-coated waveguide exhibits very strong photo-absorption of TE-polarised light - and acts as a TM-pass waveguide polariser. The absorbed TE-polarised light causes a significant temperature increase in the GO film and induces thermal reduction of the GO, resulting in an increase in optical-frequency conductivity and consequently increased optical propagation loss. This behaviour in a GO-coated waveguide gives the action of an inverted optical switch/modulator. By varying the incident TE-polarised light power, a maximum modulation efficiency of 72% was measured, with application of an incident optical power level of 57 mW. The GO-coated waveguide was able to respond clearly to modulated TE-polarised light with a pulse duration of as little as 100 μs. In addition, no wavelength dependence was observed in the response of either the modulation (TE-polarised light) or the signal (TM-polarised light).