Thermotransmittance spectroscopy of layered crystals using lab on fiber†

Transition metal dichalcogenides are extensively studied for their unique optical properties, with emission and reflectance techniques commonly used to probe optical transitions. In this context, a thermotransmittance technique is introduced as a novel method to investigate the transmission and absorption properties of thin TMDC crystals transferred onto the core of multimode optical fibers. Using transmission and photomodulated transmission techniques, significant changes in the amount of transmitted light, reaching almost 60%, were detected. These changes, evoked by laser heating and subsequent heat accumulation, correspond to excitonic transitions. The obtained results indicate significant red shifts and changes in absorption coefficients around optical transitions, highlighting the materials’ sensitivity to temperature variations. As the laser illumination of the sample causes either an energy shift of optical transition or a change in the amount of transmitted light, these findings demonstrate that the TMDC-coated optical fibers could be utilized as light modulators or temperature sensors.