We demonstrate a novel all-fiber-optic humidity sensor comprised of a WS₂ film overlay on a side polished fiber (SPF). This sensor can achieve optical power variation of up to 6 dB in a relative humidity (RH) range of 35%-85%. In particular, this novel humidity fiber sensor has a linear correlation coefficient of 99.39%, sensitivity of 0.1213 dB/%RH, and a humidity resolution of 0.475%RH. Furthermore, this sensor shows good repeatability and reversibility, and fast response to breath stimulus. This WS₂ based all-fiber optic humidity sensor is easy to fabricate, is compatible with pre-established fiber optic systems, and holds great potential in photonics applications such as in all-fiber optic humidity sensing networks.

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.

In this work, we demonstrate a highly-sensitive vector magnetometer based on a few-mode-fiber-based surface plasmon resonance (SPR) sensor functionalized by magnetic nanoparticles (MNPs) in liquid. To fabricate the sensor, a few-mode fiber is side-polished and coated with a gold film, forming an SPR sensor that is highly sensitive to the surrounding refractive index. The vector magnetometer operates based on the mechanism whereby the intensity and orientation of an external magnetic field alters the anisotropic aggregation of the MNPs and thus the refractive index around the fiber SPR device. This, in turn, shifts the resonance wavelength of the surface plasmon. Experimental results show the proposed sensor is very sensitive to magnetic-field intensity and orientation (0.692 nm/Oe and −11.917 nm/°, respectively). These remarkable sensitivities to both magnetic-field intensity and orientation mean that the proposed sensor can be used in applications to detect weak magnetic-field vectors.

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.

A high-sensitivity and fast-response fiber-optic plasmonic temperature sensor is developed by coating graphene and polydimethylsiloxane (PDMS) onto an optical-fiber based plasmonic interface. The sensor is composed of a side-polished-fiber for light excitation and readout, a gold layer to excite surface plasmon resonance (SPR), graphene layers to enhance the SPR effect and accelerate the sensing response, and a PDMS layer acting as a thermo-optical responsive material. It is found that the number of graphene layers exhibits positive enhancement on the sensitivity toward the refractive index (RI) until 4 layers, and further increasing the number of layers leads to a decreased sensitivity. The four-layered graphene could improve the sensitivity of the RI sensor by 33% and the temperature sensitivity by 21.9% after overcoating the PDMS layer, increasing the temperature sensitivity from 1.28 nm °C⁻¹ for the SPR sensor with a PDMS layer to only 1.56 nm °C⁻¹ for the graphene–PDMS based sensor. Furthermore, the graphene layers shorten the response time of the temperature sensor by more than one order of magnitude, i.e., from 65 to 6 s. It is believed that the multilayer graphene/PDMS structure can be further exploited for optimizing other temperature sensors in terms of sensitivity and response time.

Two‐dimensional (2D) materials exhibit fascinating and outstanding optoelectronic properties, laying the foundation for the development of novel optoelectronic devices. However, ultra‐weak light absorption of 2D materials limits the performance of the optoelectronic devices. Here, a structure of MoS ₂ /graphene/Au integrated onto the side‐polished fiber (SPF) is proposed to achieve a high‐performance fiber‐integrated multifunction‐in‐one optoelectronic device. It is found that the device can absorb the transverse magnetic (TM) mode guided in the SPF and generate photocurrents as a polarization‐sensitive photodetector, while the transverse electric (TE) mode passes with low loss through the device, making the device simultaneously a polarizer. In the device, the MoS ₂ film and the Au finger electrode can enhance the TM absorption by 1.75 times and 24.8 times, respectively, thus allowing to achieve high performance: a high photoresponsivity of 2.2 × 10 ⁵ A/W at 1550 nm; the external quantum efficiency (EQE) of 1.76 × 10 ⁷ %; a high photocurrent polarization ratio of 0.686 and a polarization efficiency of 3.9 dB/mm at C‐band. The integration of 2D materials on SPF paves the way to enhance the light–2D material interaction and achieve high performance multifunction‐in‐one fiber‐integrated optoelectronic devices.