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Laser-diode self-mixing interferometry is a noncontact technique widely used both in industries and laboratories. In this paper, we propose to extend the self-mixing approach to low-coherence sources such as superluminescent diodes. In particular, we present a fiber-based common-path interferometer exploiting a single-mode-pigtailed superluminescent diode. The developed measuring system has been demonstrated to be able to directly measure the flow in pipes. To the best of our knowledge, it is the first time that flow measurements have been performed by a single-arm self-mixing pigtailed superluminescent-diode. The measuring system exploits the Doppler interference pattern produced by the light back-reflected from the inner facet of the pipe wall and the light back-diffused by the moving particles. Then, the use of a low-coherence source allows to measure the velocity of the scattering particles in a fixed and well-defined region located close to the pipe wall, thus providing good robustness to variations of scatterers concentration and allowing to easily estimate the flow under the laminar flow assumption. Experimental results demonstrated a high linearity (Pearson coefficient of about 99\%) and sensitivity of about 16.62 \pm 1.1 cm ^-3, with flows ranging from 1 to 15 cm ^3/s and scatterers volume concentration ranging from 0.015 to 0.36$\%$. [ABSTRACT FROM PUBLISHER]

The papers in this special section focus highlight the advancement of guided lightwaves in applications to sensors, instrumentation and measurement. [ABSTRACT FROM PUBLISHER]

Theoretical and experimental analysis of the spectral characteristics of the signal acquired from self-mixing laser Doppler of extracorporeal blood flow is presented. The theoretical spectrum of the predetected signal is calculated in the single scattering approximation and assuming a parabolic velocity profile in the duct. The resulting signal is mixed in a diode laser cavity to generate the sensor output. Theoretical predictions are verified by measurements performed on blood and phantoms flowing in an extracorporeal circulation system. [ABSTRACT FROM PUBLISHER]

A novel optical method for noninvasive monitoring of the ocular fundus status is presented. The method could provide an optimal end-point for transpupillary thermotherapy treatment, thus overcoming the severe over- and under-treatment issues currently affecting about 10% of patients. The developed instrument and measurement procedure have been tested on both a mechanical eye model and animal models. The presented results demonstrate the ability of our system to potentially detect variations in both blood flow and optical properties. Much more work will be needed before the developed instrument will be ready for clinical test, nevertheless the proposed method may provide an important improvement in the treatment of several disabling ocular diseases. [ABSTRACT FROM PUBLISHER]