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• A fiber-optic Michelson interferometric trace DMMP sensor was proposed. • The fiber-optic sensor has the structure of a Michelson interferometer. • ZIF-8@Ag/PDDA as sensing materials is used to enhance the sensitivity. • The sensor has a sensitivity of 45.71 dB/ppm for DMMP. • The sensor has good selectivity and stability. A Michelson interference dimethyl methyl phosphate (DMMP) fiber sensor with a single-mode (SMF)-dislocated single-mode (DSMF)-hollow-core fiber (HCF) structure is proposed. To fabricate the Michelson interference structure of SMF-DSMF-HCF, one end of the DSMF was misaligned and fused to the SMF, the other end was fused to the HCF to generate a reflective surface. The structure, elemental composition, and surface morphology of ZIF-8@Ag were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy after the ZIF-8@Ag/PDDA composite was coated on the surface of DSMF. The result shows that the sensitivity and the detection limit of the sensor are 45.71 dB/ppm and 0.1431 ppb, respectively, and the response/recovery time is around 14/12 s. The sensor also has excellent selectivity and stability. [ABSTRACT FROM AUTHOR]

• A fiber-optic SPR hydrogen sulfide (H 2 S) gas sensor is proposed. • The Ag/APTES/Cu-MWCNT sensing film is coated on the surface of SMF. • H 2 S concentration and the resonance wavelength shift (117.421 nm) satisfy the linear relationship within 1–10 ppm. • The sensitivity and detection limit are 12.98 nm/ppm and 0.146 ppm, respectively. • The response time is about 28 s, and can be used to monitor trace H 2 S gas. A fiber-optic surface plasmon resonance (SPR) hydrogen sulfide (H 2 S) gas sensor is proposed and fabricated by using silver/triaminopropyltriethoxysilane/copper-multiwalled carbon nanotubes (Ag/APTES/Cu-MWCNT) as sensing film. A single-mode fiber (SMF) is spliced between two multimode fibers (MMF) to form an MMF-SMF-MMF sensing structure. The Ag/APTES/Cu-MWCNT sensing film is coated on the surface of SMF. The performance and stability of the sensor were investigated in detail. With the increase of H 2 S concentration in the range of 10–100 ppm, the redshift of the resonance dip reaches 126.465 nm, and the logarithm of H 2 S concentration and the resonance dip wavelength shift satisfy the linear relationship. In the range of 1–10 ppm, the wavelength shifts 117.421 nm, and H 2 S concentration and the dip wavelength shift meet a linear relationship. The sensitivity (12.9849 nm/ppm) is obtained, the detection limit (0.146 ± 0.031 ppm) is determined, and the response time is about 28 s. The sensor has excellent selectivity, good time, humidity and temperature stability, which has potential application in the field of trace H 2 S gas monitoring. [ABSTRACT FROM AUTHOR]