A giant Goos–Hänchen (G-H) shift in graphene has been theoretically predicted by previous research. In this Letter, we present experimental measurements of the G-H shift in graphene, in a total internal reflection condition, using a new method we have named “the beam splitter scanning method.” Our results show that a focused light source undergoes significant lateral shift when the polarization of incident light changes from transverse magnetic (TM) to transverse electric (TE) mode, indicating a large G-H shift in graphene that is polarization-dependent. We also observed that the difference in the G-H shift for TM versus TE modes increases with increasing thickness of graphene material. A maximum difference of 31.16 μm was observed, which is a significant result. Based on this research, the ability to engineer giant G-H shifts in graphene material has now been experimentally confirmed for the first time to the best of our knowledge. We expect that this result will lead to significant new and interesting applications of graphene in various types of optical sensors, and more.
The nonlinear optical and optical limiting properties of an oligothiophene (6THIOP) covalently functionalized graphene hybrid material (Graphene-6THIOP) were investigated by using Z-scan technique with a 5ns Q-switched pulsed laser at 532 nm. Results show that the hybrid material of Graphene-6THIOP exhibits enhanced nonlinear optical and optical limiting properties in comparison to individual 6THIOP, graphene moiety and C60. The enhanced nonlinear optical properties of Graphene-6THIOP should be attributed to the combination of the observed nonlinear scattering with the possible photoinduced electron or energy transfer mechanism between 6THIOP moiety and graphene.
We experimentally demonstrate an operation switchable Erbium-doped fiber laser by employing graphene saturable absorber (GSA) on microfiber. With the introducing of a polydimethylsiloxane layer, a graphene can be considered as a parallel plate on microfiber and induces different propagation losses to TE and TM modes. By the use of such polarization sensitive GSA on microfiber, Erbium doped fiber laser with switchable operation states such as continuous wave, stable Q-switching, Q-switched mode-locking, and continuous-wave mode-locking, can be achieved by simply tuning the polarization states in the laser cavity. Our results show that covering graphene on microfibers could be a promising method for fabricating all fiber SA, and may have high potential in wide applications.
Using a two-layer structure consisting of polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS) to support graphene grown by chemical vapor deposition (CVD), we demonstrate a flexible integrated graphene saturable absorber (SA) on microfiber for passive mode-locked soliton fiber laser. This method can optimize the light-graphene interaction by using evanescent field in the integration structure. Moreover, the fiber laser with the in-line microfiber-to-graphene SA can realize the tunabilities of both the 3dB bandwidth of output optical spectrum and the pulse width of soliton. This tunable mode-locked soliton laser has potential applications in optical communication, optical microscopy, and so on.