In this paper, a low-cost long-period fiber grating (LPFG) induced by a polymeric microstructure is demonstrated.
LPFGs are induced on a tapered optical fiber (TOF) when a periodic micro-grating comes into contact with the thin
region of the fiber. The micro-grating device is made using polydimethylsiloxane (PDMS), an inexpensive, nontoxic and
optically transparent polymer that is extensively used in microfluidics, organic electronics and biotechnological
applications. Soft lithography, along with molds built from thermoplastic polystyrene sheets, makes the fabrication
straightforward and extremely low-cost. Additionally, no precision machining is necessary and the resolution of the
microstructures is limited only by the resolution of the laser printer used for patterning the polystyrene sheets.
The TOF and the micro-grating were dimensionally characterized using optical microscopy and white light
interferometry, respectively. Variations on the optical spectrum due to pressure and temperature were observed and their
magnitudes were similar to those obtained using metallic microstructures. Thus, LPFGs can be made in an inexpensive
and expeditious way using PDMS and TOFs. These polymeric devices can be integrated into microfluidic and other labon-
a-chip systems where biocompatibility is a valuable characteristic.