Abstract:

       We employed electrostatic layer-by-layer self-assembly method to coat poly(diallyldimethylammonium chloride) (PDDA)/poly(sodium styrenesulfonate) (PSS) films on the surface of a long-period fiber grating (LPFG), and addressed their response to the humidity of air. Experimental results show that the central wavelengths in the transmission spectrum gradually shift to long wave with the increase of absolute humidity. A good linear relationship exists between absolute humidity and the central wavelength in the range of 25~45 ℃. A PDDA/PSS coated LPFG therefore has potential application prospect in a humidity sensor.

Key words: long-period fiber grating, PDDA, PSS, polymer films, humidity sensors