We introduce a new type of distributed fiber strain sensor that leverages the high intensity and linewidth narrowing associated with the Brillouin lasing transition to precisely measure the Brillouin resonant frequency at discrete locations along a fiber. The system operates by exciting a series of lasing modes that experience Brillouin amplification at discrete spatial locations in a fiber. We introduce the basic operating principle and modifications enabling practical operation. Finally, we demonstrate sensing with wide dynamic range (>5 mε) and ultra-low noise (4 nε/√Hz) in 400 m of fiber with 4 m spatial resolution and a bandwidth of ~10 kHz.

A miniaturized fiber-optic Raman probe for Raman spectroscopy, which can eliminate the high backscattering Raman signal from the long-fused silica fiber that is used for the biochemical application, is presented. Its main purpose is to provide a technique for the detection of very small substances and separate Raman backscattering signal of optical fiber. After a brief introduction of the traditional fiber Raman technology, the experimental operation of the design optimization of the miniaturized fiber-optic Raman probe was discussed. We successfully used the home build fiber taper device to combine seven multi-mode fibers as one fiber taper with approximately 30µm as the probe diameter for Raman spectral analysis. By comparing the traditional fiber-optic Raman sensor and the miniaturized fiber-optic Raman probe with experiments on a variety of materials, the correlation of the Raman signal has been demonstrated. We observed that the miniaturized fiber-optic Raman probe not only effectively removes the backscattering Raman signal of the fiber itself, but also provides a comparable signal-noise ratio, which provides an argument for this research.

Anello Photonics (Anello) is developing a new miniature Silicon Photonics Optical Gyro (SiPhOG) that can deliver a ten times or greater reduction in Size Weight and Power (SWAP-C) for high-precision rotational rate measurement and Inertial Navigation Systems (INS) as compared to state-of-the-art solutions. Currently, gyroscopes are bifurcated into two primary products and use cases: MEMS-based sensors satisfy the consumer market for commercial use cases and Fiber Optic Gyro (FOG) based sensors satisfy high-end navigation use cases. The Anello SiPhOG is manufactured using a semiconductor-based silicon photonic integrated circuit process, and therefore, Anello’s SiPhOG sensor will be lower priced while operating just as effectively as high-grade sensors. The SiPhOG consists of a planar silicon nitride waveguide direct coupled to a silicon photonic integrated circuit. The waveguide process is custom developed by Anello in a commercial fab and features extremely low-loss.

The continuous casting process for steel production utilizes specially designed oxyfluoride glasses (mold fluxes) to lubricate the mold and control the steel solidification process. The composition of the flux controls important properties, such as viscosity, basicity, and crystallization rate, which in turn influences the quality of the as-cast product. However, these fluxes also interact with the steel during casting, causing chemistry shifts that must be anticipated in the design of the flux. Today, the in-service chemistry of the flux must be determined by taking flux samples from the mold during casting and then processing the samples off-line to determine chemistry and other physical properties, such as viscosity. Raman spectroscopy provides an alternative method for flux analysis, with the possibility of performing direct on-line analysis during casting. Raman spectroscopy has the unique ability to identify specific molecules through well-resolved vibrational bands that provide fingerprint signatures of the structure of the molecules. Specific peaks in the Raman spectra can be correlated with flux chemistry and viscosity. The work reported here aims to assess the structure and chemical composition of flux samples at high temperatures using fiber-optic Raman spectroscopy. Results from Raman spectral analyses captured the 1300 °C for a range of flux chemistries are presented. The experimental results demonstrate that the composition-dependent Raman signal shift can be detected at high temperatures and that on-line flux analysis using a high-temperature Raman system shows significant promise.