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Proceedings Paper

Using a multimode fiber as a high-resolution, low-loss spectrometer
Author(s): B. Redding; H. Cao
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Paper Abstract

The development of optical fibers has revolutionized telecommunications by enabling long-distance broad-band transmission with minimal loss. In turn, the ubiquity of high-quality low-cost fibers enabled a number of additional applications, including fiber sensors, fiber lasers, and imaging fiber bundles. In this work, we show that a multimode optical fiber can also function as a spectrometer by measuring the wavelength-dependent speckle pattern formed by interference between the guided modes. In practice, the wavelength-dependent speckle patterns are recorded in a transmission matrix. After calibration an arbitrary input spectra can be reconstructed based on the speckle pattern it produces. The spectral resolution is dictated by the change in wavelength required to produce an uncorrelated speckle pattern, which scales inversely with the length of the fiber. Using a 100 meter long multimode fiber, we were able to resolve two lines separated by merely 1 pm at a wavelength of 1500 nm. Broad-band operation is also possible by using a shorter fiber with lower resolution. We showed that a 4 cm fiber can provide 350 nm of bandwidth across the visible spectrum with 1 nm resolution. The fiber spectrometer consists only of a multimode fiber and a monochrome camera used to record the speckle patterns. Since the fiber can be coiled into a small volume, the entire spectrometer can be compact, lightweight, and low cost while providing ultrahigh resolution, broad bandwidth, and low loss.

Paper Details

Date Published: 18 June 2014
PDF: 5 pages
Proc. SPIE 9098, Fiber Optic Sensors and Applications XI, 90980G (18 June 2014); doi: 10.1117/12.2050020
Show Author Affiliations
B. Redding, Yale Univ. (United States)
H. Cao, Yale Univ. (United States)

Published in SPIE Proceedings Vol. 9098:
Fiber Optic Sensors and Applications XI
Henry H. Du; Gary Pickrell; Eric Udd; Christopher S. Baldwin; Jerry J. Benterou; Anbo Wang, Editor(s)

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