Magnetic-Based Polydimethylsiloxane Cap for Simultaneous Measurement of Magnetic Field and Temperature

In this paper, a cascaded Fabry-Perot (FP) cavity interferometer for detection of small magnetic field and temperature is proposed. Ferromagnetic material (e.g.,
Mn
₃
O
₄
nanocrystals), which is filled into polydimethylsiloxane
(Mn
₃
O
₄
-PDMS), serves as a cavity cap and comprises of the main section of the cascaded FP interferometer. When applied the strength of the external field, magnetic forces acting on its surface and causing a variation in the cavity length thus modulates the interference spectra. Experimental results show that the proposed sensor can provide a maximum linear sensitivity of 563.2 pm/mT within a linear magnetic field intensity ranging from 0 to 4 mT and a temperature sensitivity of 1160 pm/°C, around the wavelength of 1550 nm. With its compactness, and ease of fabrication, the proposed sensor would find potential applications in the measurement of small magnetic field.