Abstract: An optical sensor has a waveguide having a core, a cladding having an outer surface and a long period fiber grating. The core, the cladding and the long period fiber grating collectively provide at least two resonant wavelengths. The optical sensor also has binding sites on the outer surface of the cladding for binding to elements to be detected to the outer surface of the cladding. The cladding may be thinned down to a thickness sufficiently low produce the resonant wavelengths. The binding sites include agents for binding to the elements to be detected with the agents being covalently bonded to the surface of the cladding. Example binding sites can include bacteriophages for detecting E. coli bacteria, Palladium for detecting hydrogen, or synthetic DNA for detecting viruses of certain molecules for example.

Abstract: An optical sensor having dual resonant long period gratings (DRLPGs) separated by an inter-grating fiber spacing IGS of a length and material to provide temperature insensitivity over a wide wavelength range. The materials of the IGS and DRLPGs are such that the difference between the dn/dT of the core and the dn/dT of the cladding in the IGS is opposite in sign to that of the DRLPGs. The DRLPGs and the IGS are also composed of materials and have dimensions such that the turn-around points ?D, as well as the general functional form of the respective spectral variation of their propagation constant difference ?? versus wavelength are substantially similar.

Abstract: An optical sensor has a waveguide having a core, a cladding having an outer surface and a long period fiber grating. The core, the cladding and the long period fiber grating collectively provide at least two resonant wavelengths. The optical sensor also has binding sites on the outer surface of the cladding for binding to elements to be detected to the outer surface of the cladding. The cladding may be thinned down to a thickness sufficiently low produce the resonant wavelengths. The binding sites include agents for binding to the elements to be detected with the agents being covalently bonded to the surface of the cladding. Example binding sites can include bacteriophages for detecting E. coli bacteria, Palladium for detecting hydrogen, or synthetic DNA for detecting viruses of certain molecules for example.