A grating-less fiber vector bend sensor is demonstrated using a standard single mode fiber spliced to a multimode fiber as a multimode interference device. The ring-shaped light intensity distribution at the end of the multimode fiber is subject to a vector transition in response to the fiber bend. Instead of comprehensive imaging processing for the analysis, the image can be tapped out by a seven-core fiber spliced to the other end of the multimode fiber. The seven-core fiber is further guided to seven single mode fibers via a commercial fan-out device. By comparing the relative light intensities received at the seven outputs, both the bend radius and its direction can be determined. Experiment has shown that a slight bend displacement of 10 µm over a 1.2-cm-long multimode fiber in the X direction (bend angle of 0.382°) causes a distinctive power imbalance of 4.6 dB between two chosen outputs (numbered C4 and C7). For the same displacement in the Y direction, the power ratio between the previous two outputs C4 and C7 remains constant, while the imbalance between another pair (C3 and C4) rises significantly to 7.0 dB.
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http://dx.doi.org/10.3390/s19020321 | DOI Listing |
J Biomed Opt
January 2025
The Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland, United States.
Significance: Laparoscopic surgery presents challenges in localizing oncological margins due to poor contrast between healthy and malignant tissues. Optical properties can uniquely identify various tissue types and disease states with high sensitivity and specificity, making it a promising tool for surgical guidance. Although spatial frequency domain imaging (SFDI) effectively measures quantitative optical properties, its deployment in laparoscopy is challenging due to the constrained imaging environment.
View Article and Find Full Text PDFLight Sci Appl
January 2025
Wuhan National Laboratory for Optoelectronics, Next Generation Internet Access National Engineering Laboratory, and Hubei Optics Valley Laboratory, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China.
We propose and validate a novel optical semantic transmission scheme using multimode fiber (MMF). By leveraging the frequency sensitivity of intermodal dispersion in MMFs, we achieve high-dimensional semantic encoding and decoding in the frequency domain. Our system maps symbols to 128 distinct frequencies spaced at 600 kHz intervals, demonstrating a seven-fold increase in capacity compared to conventional communication encoding.
View Article and Find Full Text PDFBiomed Opt Express
January 2025
Faculty of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
In fiber-based confocal microscopy, using two separate fibers for illumination and collection enables the use of a few-mode fiber to achieve an effect similar to opening the pinhole in a conventional confocal microscope. In some Fourier-domain applications, however, or when a spectral measurement is involved, the coherent light detection would lead to noticeable spectral modulation artifacts that result from differential mode delay, an effect caused by the multimode propagation in the collection fiber. After eliminating these artifacts by using mode-dependent polarization control, we demonstrate effective spectrally encoded imaging with improved signal efficiency and lower speckle noise, and only a minor, negligible reduction in lateral and axial resolutions.
View Article and Find Full Text PDFA novel, to the best of our knowledge, approach for the modal decomposition of a fiber laser beam is demonstrated using a spatial mode multiplexer. Since the modal decomposition is carried out optically, this approach is able to obtain the modal content at speeds up to the GHz level. In order to demonstrate such performance, we have applied this approach to the modal analysis of a -switched pulse generated in a multimode fiber with alternating intra-pulse mode content.
View Article and Find Full Text PDFFree space optical communication (FSOC) technology can be used for data transmission between ocean islands as backup wireless communication networks to cope with traffic surges and emergencies. In this paper, we experimentally demonstrate the results of a 24-h real-time single-wavelength 2.5-Gbps FSOC between two islands 29 km apart at a low altitude with low complexity.
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