High-mechanical-strength single-pulse draw tower gratings

The inscription of fiber Bragg gratings during the drawing process is shown to be a very useful method to realize sensor arrays with high numbers of gratings and excellent mechanical strength and also type two gratings with high temperature stability. Results of single pulse grating arrays with numbers between ten and >100 and definite wavelengths and positions for sensor applications were achieved at 1550nm and 830nm using new photosensitive fibers developed in IPHT. Single pulse type-1 gratings at 1550 nm with more than 30% Reflectivity were shown first time to our knowledge. The mechanical strength of this fiber with an Ormocer coating with those single pulse gratings is the same like standard telecomm fibers. Weibull plots of fiber tests will be shown. At 830 nm we reach more than 10% reflectivity with single pulse writing during the fiber drawing in photosensitive fibers with less than 16 dB transmission loss. These gratings are useful for stress and vibration sensing applications. Type two gratings with reflectivity near 100% and smooth spectral shape and spectral width of about 1 nm reach temperature stability above 1200 K. They are also realized in the fiber drawing process. These Gratings are useful for temperature sensor applications.