This paper presents a Fabry-Perot fiber tip sensor based on an air-liquid filled cavity. The cavity is sealed off by a thin gold coated membrane of parylene C, between 300 and 350 nm, creating a particularly flexible diaphragm. In order to retrieve and track the cavity of interest from other cavities formed within the sensor tip, a signal processing of the feedback signal is performed by inverse fast Fourier transform. The experimental sensor has been manufactured and tested for temperature, giving cavity length sensitivities of 6.1 nm/°C and 9.6 nm/°C for temperature increase and decrease respectively. The external gas pressure response gives a sensitivity of 15 nm/kPa. The fiber sensor has also been adapted for force sensing after silicone embedment and has shown a sensitivity of about 8.7 nm/mN. Finally, the sensor has been tested on insertion into a human temporal bone, proving that it could be an interesting candidate for insertion force monitoring for robotic cochlear implantation.

The temperature measurement of a drill bit during an implantology drilling process is proposed by using a fiber Bragg grating fitted inside the drill bit. Due to the rotational nature of the drilling process, a free-space fiber-optic rotary joint is used for interrogating the fiber Bragg grating. Due to mechanical clearances and interferometric noise induced at this rotary joint, signal integrity is strongly deteriorated and is not workable without adequate measures. These measures involve a proper fiber lensing and a signal processing in order to remove the interferometric noise. Finally, a heating measurement on an implantology drill bit is performed and discussed for drilling several holes on a pork jaw sample. (C) 2019 Optical Society of America

We present a new approach for producing elastomeric optical fibers with an optical behaviour corresponding to a few-mode optical fiber. Different fibers have been produced by first fabricating thermoplastic polyurethane preforms and subsequently drawing them. The fiber attenuation has been measured by the cut-back technique and the fiber bending transmission tolerance evaluated. The fiber potential has been assessed through two basic experiments in order to highlight the benefits of elasticity and a reduced core diameter. Future potential of the proposed fiber is discussed and shows a very auspicious path towards new and unexplored applications.

An elastomeric optical fiber core was fabricated by drawing a 1160-D thermoplastic polyurethane preform. The cut-back technique was used to measure fiber attenuation for a light spectrum ranging from 550 nm to 875 nm, resulting in an average value of less than 0.25 dB/cm, which is suitable for use in short-distance applications. The potential of the fiber was evaluated in two applications where the advantages of this type of optical fiber, its elasticity and flexibility, are important. In the first application, for weight measurement, the sensor response showed asymptotic behavior at high weights that can be divided into two linear sections of 2.9 dB/N for weights ranging from 0 N up to 1 N, and 2.1 dB/N for 1 N to 1.7 N. In the second application, as a vibration sensor, signals were detected between 1 kHz and 20 kHz with an amplitude of approximately 35 dB above the background noise.

We present an enhanced performance Brillouin optical time-domain analysis sensor that uses dual probes waves with optical frequency modulation and cyclic coding. The frequency modulation serves to increase the probe power that can be injected in the fiber before the onset of non-local effects and noise generated by spontaneous Brillouin scattering. This leads to higher detected signal-to-noise ratio (SNR), which is further increased by the coding gain. The enhanced SNR translates to extended range for the sensor, with experiments demonstrating 1-m spatial resolution over a 164 km fiber loop with a 3-MHz Brillouin frequency shift measurement precision at the worst contrast position. In addition, we introduce a study of the power limits that can be injected in the fiber with cyclic coding before the appearance of distortions in the decoded signal. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

This paper discusses the design, fabrication, and use of thermoplastic polyurethane optical fibers intended for oxygen saturation measurements. It includes an evaluation of the fiber attenuation and the creation of two probes for the measurement assessment. For comparison, a third probe is made using conventional glass optical fibers. The assessment is conducted in two stages: first, absorption measurements are performed using a mixture of methylene blue and intralipid diluted in deionized water; second, a measurement with human blood is conducted to demonstrate the effectiveness of such fibers in measuring blood oxygen saturation. Additionally, a comprehensive study of measurement stability is provided.