A single mode-multimode-single mode structure (SMS) has been used for developing a magnetic field sensor without using magnetic fluids. The SMS optical fiber was coated with a magneto-optical material by means of sputtering. The sputtering process was monitored in order to achieve the optimum thickness of the coating and the best sensitivity. Sensitivities of 1.45 dB/T and 6 nm/T have been achieved. Repeatability in the fabrication and in the behaviour of the device has been checked.
Link to source: https://ieeexplore.ieee.org/abstract/document/7370226
The SMS optical fiber was introduced to the vacuum chamber of a Pulsed DC Sputtering System (Nadetech, Inc.). It offers the possibility of monitoring changes in the spectrum while the sputtering process is being done.