A point-by-point dip coating method has been proposed and demonstrated for fabricating long-period gratings (LPGs) in microfibers. Using a high precision 3D translation stage, the grating structure is formed by periodically immersing the microfiber into a miniature polydimethylsiloxane droplet suspended at the end-tip of the single mode fiber.
A 10-period LPG with a grating period of about 143 μm fabricated in the 7.6 μm diameter microfiber demonstrates a resonant dip of 19 dB. Investigations of the strain and temperature response characteristics of the fabricated devices show that the devices have great potential for tunable filter and sensor applications with the merits of flexibility and compactness.