| 摘要 |
A light source 500 illuminates long period grating 508 acting as a sensor disposed between two fibre Bragg gratings 504, 506 (each with different Bragg wavelengths) in optical fibre 104. Port circulator 502 directs light from light source 500 to gratings 504, 506, 508 and then to receivers 514, 518. Light reflected from first Bragg grating 504 passes through port circulator 502 and is reflected by filter 510 before passing through port circulator 502 again and being detected by receiver 2. Light reflected by second Bragg grating 506 passes through port circulator 502 and is detected by receiver 1. Light reflected by second Bragg grating 506 suffers an induced loss in long period grating 508. Analyzer 516 compares the ratio of reflected wavelengths from Bragg gratings 504, 506 and determines the strain, pressure or stress applied to long period grating 508. |
