Low-cost microlens array for long-period grating fabrication
A low-cost technique using commercial UV-grade fibres to construct a microlens array that is suitable for the mass-production of long-period gratings is reported. The array can withstand in excess of 1 J/cm2 per 20 ns pulses of 248 nm laser light. The growth rate of long-period gratings fabricated using the array is four times faster than that possible using a metal mask.