Graphene-based electrical chemical vapor sensors can achieve extremely high sensitivity, whereas the comparatively slow sensing response and recovery, the research focused on only low concentration detection, have been known as drawbacks for many applications requiring rapid and high concentration detection. Here we report a novel graphene-based fiber-optic relative humidity (RH) sensor relying on fundamentally different sensing mechanism. The sensor can achieve power variation of up to 6.9 dB in high relative humidity range (70-95%), and display linear response with correlation coefficient of 98.2%, sensitivity of 0.31 dB/%RH, response speed of faster than 0.13%RH/s, and good repeatability in 75-95%RH. Theoretical analysis of sensing mechanism can explain the experimental result, and reveal the broad applying prospect of the sensor for other kinds of chemical vapor detection. This novel graphene-based optical sensor provides a beneficial complement to the existing electrical ones, and will promote the employment of graphene in chemical sensing techniques.

We demonstrate a novel all-fiber-optic temperature sensor based on a reduced graphene oxide (rGO) film coated onto a side-polished fiber (SPF). Significantly enhanced interaction between the propagating light and the rGO film can be obtained via strong evanescent field of the SPF. The strong light-graphene interaction results in temperature sensing with a maximum optical power variation of 11.3 dB in the SPF experimentally. The novel temperature fiber sensor has a linear correlation coefficient of 99.4%, a sensitivity of 0.134 dB • C −1 , a precision of better than 0.03 • C, and a response speed of better than 0.0228 • C s −1 . Such an rGO-based all-fiber-optic temperature sensor is easy to fabricate, is compatible with fiber-optic systems, and possesses high potentiality in photonics applications such as all-fiber-optic temperature sensing networks.

We demonstrated temperature sensing of a fiber with nanostructured cladding, which was constructed by titanium dioxide TiO2 nanoparticles self-assembled onto a side polished optical fiber (SPF). Significantly enhanced interaction between the propagating light and the TiO2 nanoparticles (TN) can be obtained via strong evanescent field of the SPF. The strong light-TN interaction results in temperature sensing with a maximum optical power variation of ~4dB in SPF experimentally for an external environment temperature varying from -7.8°C to 77.6°C. The novel temperature sensing device shows a linear correlation coefficient of better than 99.4%, and a sensitivity of ~0.044 dB/°C. The TN-based all-fiber-optic temperature sensing characteristics was successfully demonstrated, and it is compatible with fiber-optic interconnections and high potential in photonics applications.

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