Environmental sensor based on optical-resonance-enhancement in a MoS2 printed D-shaped single-mode fiber

Molybdenum disulfide (MoS2) has emerged as a versatile two-dimensional material platform for many optical and optoelectronic applications due to its layer-dependent band structure, which can be tuned from direct to indirect by increasing the number of layers. In this work, the integration of MoS2 layers onto a D-shaped side-polished optical fiber has been demonstrated using an inkjet printing technique. We show that MoS2 devices exhibit a strong wavelength dependent transmission spectrum, with a transmittance dip of ~ –50 dB, which can be tuned from near to the mid-infrared wavelength regions by varying the printing paths. Exposure of the MoS2 device to deionized water has revealed that the wavelength position of dip changes by more than 70 nm in response to the mode's interaction with the liquid. These results indicate that inkjet-printed MoS2 devices could find applications for the development of environmental gas or humidity sensors.