Fiber In-Line Fabry-Perot Interferometer With Offset Splicing for Strain Measurement With Enhanced Sensitivity

We demonstrate a Fabry-Perot interferometer with inner air-cavity for ultrasensitive strain measurement. The device is fabricated by fusion splicing of two sections of etched multimode fiber with offset. By selecting the appropriate value of the offset, the strain sensitivity can be greatly increased. In the case of introducing two-dimensional offset, the strain sensitivity can be increased by more than 4.5 pm/με when compared with that without offset. The device is simple in fabrication, robust in structure, economic in cost, and convenient in operation, and has high potential in many strain sensing applications.