A short-range quasi-distributed strain and temperature sensing system utilizing a standard telecom laser diode

• An array of equidistant in-fiber mirrors. • A cost-effective interrogation system was built using a standard telecom DFB diode. • Sensor assembly fabricated by fs laser and standard SMF. • Sensor array has a length of 2–5 cm and contains 10 to 30 sensing segments. • Proposed device packaging for specific applications (tactile, temperature sensing…). This article presents a short-range fiber-optic quasi-distributed sensing device suitable for strain and temperature measurement. The sensing assembly consists of an fs laser inscribed reference mirror and a sensing array of equidistantly positioned mirrors. Utilization of the reference mirror and proper sensor geometry selection provides the possibility for a high-resolution spectral interrogation of the sensing array while relying on an ordinary, cost-effective distributed feedback (DFB) telecom laser diode. Beside the telecom DFB diode, the entire interrogation system includes only an additional detector, optical coupler, analog interface and a microcontroller. Measurement resolution better than 1 µ ε was demonstrated experimentally at a sampling rate exceeding 65 samples per second, while utilizing a sensing device with a typical length of 50 mm and spatial resolution of approximately 2 mm. To demonstrate the application potential of the proposed measuring device, a few different packages and sensor configurations were demonstrated and tested, including a system for tactile sensing applications and a short-range quasi-distributed temperature measurement probe.