title: Photo-induced reduction of graphene oxide coating on optical waveguide and consequent optical intermodulation.
abstract: 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).
authors.affiliation: Photonics Research Centre, Physics Department, Science Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: W Y
authors.initials: WY
authors.lastname: Chong
authors.affiliation: Photonics Research Centre, Physics Department, Science Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: W H
authors.initials: WH
authors.lastname: Lim
authors.affiliation: Heriot-Watt University Malaysia, Putrajaya, 62200 Federal Territory, Malaysia.
authors.forename: Y K
authors.initials: YK
authors.lastname: Yap
authors.affiliation: Photonics Research Centre, Physics Department, Science Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: C K
authors.initials: CK
authors.lastname: Lai
authors.affiliation: Optoelectronics Research Group, School of Engineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: R M
authors.initials: RM
authors.lastname: De La Rue
authors.affiliation: Photonics Research Centre, Physics Department, Science Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: H
authors.initials: H
authors.lastname: Ahmad