Palladium-Coated Silica Microfiber Knots for Enhanced Hydrogen Sensing

Pd-coated microfiber knot resonators (MKR) are fabricated for hydrogen sensing by measuring the shift and absorption at the resonant wavelengths of the microfiber knots. Compared with existing fiber-optic hydrogen sensors, the Pd-coated MKRs exhibit enhanced sensitivity using small interaction lengths, because the recirculation of resonant light within the MKRs significantly accumulate the hydrogen-Pd interaction. It is found that microfiber diameter of the knot is a critical factor to achieve high sensitivity.