Temperature Monitorable Refractometer of Microfiber Bragg Grating Using a Duet of Harmonic Resonances.

To overcome the temperature cross-sensitivity of the microfiber Bragg grating (m-FBG) refractometer, we propose a novel refractive-index-temperature dual-sensing paradigm involving the third harmonic Bragg resonance that presents distinctive sensing characteristics. Strong resonances are obtained in both 1060 nm and 1550 nm wavebands under the modulation of the UV Talbot pattern. Moreover, higher-order transverse mode coupled resonance is also observed at the third harmonic waveband, supplementing an independent signal for enabling a sensing trio potentially. It is believed that the proposed dual-sensing paradigm would contribute to the m-FBT-based chemoprobes/bioprobes.