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1. All-normal dispersion fiber laser with a bandwidth tunable fiber-based spectral filter

   https://doi.org/10.1364/OL.398049  

   Khanolkar, Ankita; Ge, Xiaowei; Chong, Andy (August 2020, Optics Letters)

   We investigate numerically and experimentally an all-fiber, bandwidth tunable spectral filter comprising birefringent fibers. The spectral bandwidth tunability of the filter is based on the compensation of birefringence in polarization maintaining fibers. This unique filter allows mode-locked operation of a fiber oscillator with the ability to generate distinct laser modes with different output spectral shapes and pulse evolutions. 

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2. A novel fiber length measurement technique for discontinuous fiber-reinforced composites: A comparative study with existing methods

   https://doi.org/10.1002/pc.24466  

   Goris, Sebastian; Back, Teresa; Yanev, Angel; Brands, Dave; Drummer, Dietmar; Osswald, Tim A. (June 2017, Polymer Composites)

   The residual fiber length in a molded part is one of the most important microstructural properties of discontinuous fiber‐reinforced composites. While there have been several research studies characterizing the process‐induced fiber length reduction, the measurement procedures vary substantially, calling into question the comparability of reported results. This article introduces a newly developed measurement procedure that aims to provide accurate, repeatable, robust, and time efficient fiber length analyses. A comprehensive study of measurement techniques was performed comparing commercially available systems and the conventional approach of measuring the fiber length manually. The results emphasize the need for a standardized procedure to characterize the fiber length distribution and the risk of generating inadequate results through improper sample preparation. The developed measurement technique was tested and compared for an experimental study of fiber breakage in injection molding. For a simple plaque geometry, the residual fiber length along the flow path was obtained for a long glass fiber‐reinforced polypropylene at 30 and 40%wt for varying process conditions. The new measurement technique showed accurate and repeatable results. The results of the injection molding study showed that screw speed and back pressure are important factors that drive fiber breakage. An increase in back pressure from 13 to 50 bar and screw speed from 27 to 35 rpm reduces the weight‐average fiber length by 37.5%. 

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3. Multipulsing states management in all-normal dispersion fiber laser with a fiber-based spectral filter

   https://doi.org/10.1364/OL.409339  

   Khanolkar, Ankita; Chong, Andy (January 2020, Optics Letters)

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4. A wave optics based fiber scattering model

   https://doi.org/10.1145/3414685.3417841  

   Xia, Mengqi; Walter, Bruce; Michielssen, Eric; Bindel, David; Marschner, Steve (December 2020, ACM Transactions on Graphics)

   Existing fiber scattering models in rendering are all based on tracing rays through fiber geometry, but for small fibers diffraction and interference are non-negligible, so relying on ray optics can result in appearance errors. This paper presents the first wave optics based fiber scattering model, introducing an azimuthal scattering function that comes from a full wave simulation. Solving Maxwell's equations for a straight fiber of constant cross section illuminated by a plane wave reduces to solving for a 3D electromagnetic field in a 2D domain, and our fiber scattering simulator solves this 2.5D problem efficiently using the boundary element method (BEM). From the resulting fields we compute extinction, absorption, and far-field scattering distributions, which we use to simulate shadowing and scattering by fibers in a path tracer. We validate our path tracer against the wave simulation and the simulation against a measurement of diffraction from a single textile fiber. Our results show that our approach can reproduce a wide range of fibers with different sizes, cross sections, and material properties, including textile fibers, animal fur, and human hair. The renderings include color effects, softening of sharp features, and strong forward scattering that are not predicted by traditional ray-based models, though the two approaches produce similar appearance for complex fiber assemblies under many conditions. 

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5. Spectrally Encoded Nonscanning Imaging through a Fiber

   https://doi.org/10.1021/acsphotonics.3c01582  

   Xie, Ningzhi; Tanguy, Quentin A.; Fröch, Johannes E.; Böhringer, Karl F.; Majumdar, Arka (March 2024, ACS Photonics)