Single-mode sapphire fiber temperature sensor

Journal article

Sapphire fiber can withstand temperatures of around 2000 °C, but it is multimoded, giving poor precision sensors. We have demonstrated a single-mode sapphire fiber Bragg grating temperature sensor operating up to 1200 °C. A single-mode sapphire fiber was formed by writing a depressed cladding waveguide along the length of a 100-μm diameter sapphire fiber using a femtosecond laser. A second-order Bragg grating sensor was inscribed within the waveguide, achieving a reflectivity of >90% and a narrow bandwidth of <0.5 nm. The single-mode sapphire fiber was fusion spliced to standard silica single-mode fiber. The sensor was vibration-tested over a 10 Hz to 30 kHz range with 30 μm displacement, resulting in minimal Bragg wavelength variation of <30 pm standard deviation. The sensor was furnace-tested to 1200 °C, showing ±0.08% repeatability above 1000 °C. This demonstrates the high precision sensing capability of single-mode sapphire fiber Bragg grating sensors with end-to-end single mode interrogation.

Authors: Wang, M; Salter, PS; Payne, FP; Shipley, A; Dyson, IN

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IEEE
• Journal: Journal of Lightwave Technology More from this journal
• Volume: 42
• Issue: 18
• Pages: 6409-6416
• Publication date: 2024-08-05
• Acceptance date: 2024-07-23
• DOI: 10.1109/jlt.2024.3438108
• EISSN: 1558-2213
• ISSN: 0733-8724
• Language: English
• Keywords: laser materials processing; optical fiber sensors; fiber Bragg gratings