Abstract: An in-line fiber etalon strain sensor, and method for making the sensor, is disclosed. The in-line fiber etalon strain sensor uses a short segment of silica hollow-core fiber spliced between two cleaved sections of single-mode fiber to form a mechanically robust in-line cavity. In making the sensor, a portion of a protective coating is removed from one end of each of the two cleaved sections of the single-mode fiber to form a bare portion adjacent to a partially reflective end face on each fiber section. The silica hollow core fiber is fabricated to have the same outside diameter as each of the bare portions of the fiber sections.

Abstract: A system for sensing a measurand field, the system comprising a source of broadband light, a sensor, an unbalanced optical interferometric apparatus, and a signal processor. The sensor produces an optical return signal having a wavelength functionally dependent on the measurand field. The interferometric apparatus produces an electrical interference output signal having a phase shift functionally dependent on the wavelength of the return signal, and the processor develops a processing signal indicative of the measurand field value.