Long-period gratings fabrication using piano-convex microlens array

A low-cost technique using commercial UV grade silica fibers to construct m icrolens array that is suitable for mass-production of long-period gratings is reported. The growth rate of gratings fabricated using these arrays is much faster than the conventional amplitude masks. Our previous work had sh own that this technique was 400% more efficient than the metal mask techniq ue. Further improvement of this grating writing technique using piano-conve x microlens array is reported in this paper. Under the same writing conditi ons, long-period gratings with absorption peaks of 1.5 dB and 17 dB were fa bricated by using a microlens array and a piano-convex microlens array, res pectively.