A corrugated long period microfiber grating (C-LPMFG) is fabricated by etching the corrugated LPFG down to tens of
micrometers in diameter with corrugated periodic structures made by using imprint lithography. It can be a grating
because of the periodic effective index difference caused by the corrugated structures without prestrain. During etching
of C-LPMFGs the in-situ monitoring of resonant wavelength shows that the wavelength shift varies rapidly with the
etching of fiber. The resonant dips are calculated and have similar trends compared with the experiment data. The
C-LPMFG is used as a temperature sensor with sensitivity of -146 pm/°C.
We demonstrated the splicing of 2 μm diameter microfibers by using a modified arc discharge device. Two microfibers
were aligned with the help of van der Waals forces before fusing them together by arc discharging. Most splicing losses
were below 1 dB, and the lowest was 0.16 dB. A spliced microfiber did not induce undesired wavelength selection
because arc splicing was a complete joining technique which is different from evanescent coupling. Simulation results
show splicing coupling has better averaged coupling efficiencies than evanescent one over various overlapping lengths,
and the measured results show consistency.
We demonstrate a new method that could make possible the mass production of symmetric and asymmetric corrugated long period fiber gratings (C-LPFG) by utilizing hot embossing and imprint lithography on polycarbonate (PC). The poly-dimethylsiloxane (PDMS) is imprinted on PC to create the periodic revealed region of fiber for hydrofluoric acid (HF) etching. The asymmetric C-LPFGs show some unique optical characteristics of two separate dips due to their asymmetric structures. After the torsion, the second dip would be gone and the first one would begin to shift toward shorter wavelength. It is assumed that the asymmetric C-LPFG behaves similar to the symmetric one with the torsion of a full circle. A C-LPFG was well packaged by fixing itself in the PC and having some open area close to the fiber to receive the liquid under test. The corrugated structures close to the fiber core were covered by the liquid that the packaged refractive index sensor has the sensitivity of 26.7 nm/RIU.