Theoretical modeling of fiber laser at 810 nm based on thulium-doped silica fibers with enhanced 3H4 level lifetime.

A compact upconversion fiber laser operating around 810 nm is proposed using thulium-doped silica-based fiber with locally modified thulium environment by high alumina codoping. Using a comprehensive numerical model of thulium doped fiber we investigate performance of the proposed laser. Comparison with two other thulium hosts, fluoride glass and standard silica, is presented.

Fiber-optic pH detection in small volumes of biosamples.

Determining the pH values of microscopic plant samples may help to explain complex processes in plants, so it is an area of interest to botanists. Fiber-optic probes with small dimensions can be used for this purpose. This paper deals with the fiber-optic detection of the pH values of droplets of plant xylem exudate based on ratiometric fluorescence intensity measurements with an internal reference.

Theoretical analysis of a fiber optic surface plasmon resonance sensor utilizing a Bragg grating.

A rigorous theoretical analysis of a fiber optic surface plasmon resonance sensor is presented. The sensor is based on the spectroscopy of mixed surface plasmon--fiber cladding modes excited by the fundamental mode of an optical fiber via a Bragg grating formed in the fiber core. The transmission spectrum is calculated by means of the Coupled Mode Theory.

Compact and low-cost biosensor based on novel approach to spectroscopy of surface plasmons.

A high-performance surface plasmon resonance (SPR) sensor based on a novel approach to spectroscopy of surface plasmons is reported. This approach employs a special diffraction grating structure (referred to as surface plasmon resonance coupler and disperser, SPRCD) which simultaneously couples light into a surface plasmon and disperses the diffracted light for spectral readout of SPR signal. The developed SPRCD sensor consists of a miniature cartridge integrating the diffraction grating and microfluidics and a compact optical system which simultaneously acquires data from four independent sensing channels in the cartridge.