High-Efficiency Inscription of Fiber Bragg Grating Array with High-Energy Nanosecond-Pulsed Laser Talbot Interferometer

A high-energy nanosecond-pulsed ultraviolet (UV) laser Talbot interferometer for high-efficiency, mass production of fiber Bragg grating (FBG) array was experimentally demonstrated. High-quality FBG arrays were successfully inscribed in both H2-free and H2-loaded standard single-mode fibers (SMFs) with high inscription efficiency and excellent reproducibility. Compared with the femtosecond pulse that had a coherent length of several tens of micrometers, a longer coherent length (~10 mm) of the employed laser rendered a wider FBG wavelength versatility over 700 nm band (1200–1900 nm) without the need for optical path difference (OPD) compensation. Dense FBG array with center wavelength separation of ~0.4 nm was achieved and more than 1750 FBGs with separated center wavelength could be inscribed in a single H2-free or H2-loaded SMF in theory, which is promising for mass production of FBG arrays in industry. Moreover, precise focusing of laser beam was superfluous for the proposed system due to the high energy density of pulse. The proposed FBG inscription system was promising for industrialization production of dense FBG arrays.

Holographic Interferometer for the Study of Phase Media, Which Has Four Output Channels of Different Sensitivity

Computer simulation of the interferometer combining properties of low-sensitive Talbot interferometer and high-sensitive holographic interferometer is considered. The interferometer has four output channels having different sensitivity. Channel sensibility can be varied by means of spatial filtration. The base of the interferometer is the holographic Talbot effect. The efficiency of this interferometer was verified by computer simulation method. Some results of the computer simulation are presented in the article. These results were compared with results obtained in optical experiments under the same conditions. A wide range of sensitivity of the interferometer makes it possible to use the interferometer to study complex phase objects, primarily dynamic media.