A low-cost technique using commerical UV grade silica fibers to construct microlens array that is suitable for mass-production of long-period gratings is reported. The growth rate of gratings fabricated using the array is four times faster than using metal mask.
S. Y. Liu,
"Long-period gratings fabrication using microlens array", Proc. SPIE 3746, 13th International Conference on Optical Fiber Sensors, 37462K (1 September 1999); doi: 10.1117/12.2302082; https://doi.org/10.1117/12.2302082