125 research outputs found
Single-mode sapphire fiber Bragg grating
We present here the inscription of single-mode waveguides with Bragg gratings
in sapphire. The waveguide Bragg gratings have a novel multi-layer depressed
cladding design in the 1550 nm telecommunications waveband. The Bragg gratings
have a narrow bandwidth (<0.5 nm) and have survived annealing at 1000{\deg}C.
The structures are inscribed with femtosecond laser direct writing, using
adaptive beam shaping with a non-immersion objective. A single-mode sapphire
fiber Bragg grating is created by writing a waveguide with a Bragg grating
within a 425 {\mu}m diameter sapphire optical fiber, providing significant
potential for accurate remote sensing in ultra-extreme environments.Comment: Submitted to Optica 12 November 202
High-precision optical fiber sensing beyond 1000{\deg}C
Sapphire fiber can withstand around 2000{\deg}C, but it is multimoded, giving
poor precision sensors. We demonstrate a single-mode sapphire fiber Bragg
grating temperature sensor operating up to 1200{\deg}C. The repeatability above
1000{\deg}C is within {\pm}0.08%.Comment: 4 Pages, 5 Figure
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