Single-polarization fibers are specialty optical fibers which can transmit light with a certain linear polarization direction, whereas light with the other polarization direction is either not guided or at least experiences strong optical losses. Such fibers should not be confused with polarization-maintaining fibers, which guide light with any polarization state, but can preserve a linear polarization state when the polarization direction is properly aligned with the birefringence axis.
In many cases, single-polarization guidance occurs in only a limited wavelength range. Outside that range, both polarization directions or no light at all may be guided. Also, some fibers exhibit a limited extinction ratio.
Different principles of operation can be utilized for single-polarization fibers. A common approach is the use an elliptical core, which introduces strong birefringence and also a polarization dependence of a cut-off wavelength, so that only light with one polarization direction is guided, whereas the fiber is a leaky waveguide for the other polarization. Alternatively or in addition, the rotational symmetry may be broken by structures around the fiber core, such as air holes on two sides (side-hole fibers, hole-assisted fibers). Another class of methods uses built-in mechanical stress. In any case, the birefringence serves to reduce the coupling of the two polarization directions.
There are also various types of single-polarization photonic crystal fibers. Here, a suitable arrangement of microscopic air holes again breaks the rotational symmetry and introduces polarization-dependent guiding properties.
Used in fiber lasers, single-polarization fibers guarantee polarized laser emission. There are also various uses in the field of fiber-optic sensors, where polarization effects in standard fibers can lead to unwanted effects.
Questions and Comments from Users
Here you can submit questions and comments. As far as they get accepted by the author, they will appear above this paragraph together with the author’s answer. The author will decide on acceptance based on certain criteria. Essentially, the issue must be of sufficiently broad interest.
Please do not enter personal data here; we would otherwise delete it soon. (See also our privacy declaration.) If you wish to receive personal feedback or consultancy from the author, please contact him e.g. via e-mail.
By submitting the information, you give your consent to the potential publication of your inputs on our website according to our rules. (If you later retract your consent, we will delete those inputs.) As your inputs are first reviewed by the author, they may be published with some delay.
The RP Photonics Buyer's Guide contains 4 suppliers for single-polarization fibers.
|||V. Ramaswamy et al., “Single polarization optical fibers: exposed cladding technique”, Appl. Phys. Lett. 33, 814 (1978), doi:10.1063/1.90538|
|||T. Hosaka et al., “Low-loss single polarization fibers with asymmetrical strain birefringence”, Electron. Lett. 17, 530 (1981), doi:10.1049/el:19810371|
|||K. Okamoto et al., “Polarization properties of single-polarization fibers”, Opt. Lett. 7 (11), 569 (1982), doi:10.1364/OL.7.000569|
|||T. Katsuyama et al., “Propagation characteristics of single polarization fibers”, Appl. Opt. 22 (11), 1748 (1983), doi:10.1364/AO.22.001748|
|||D. A. Nolan, “Single-polarization fiber with a high extinction ratio”, Opt. Lett. 29 (16), 1855 (2004), doi:10.1364/OL.29.001855|
|||D. T. Walton et al., “Challenges in single-polarization fibers”, Proc. SPIE 5709, 316 (2005), doi:10.1049/el:19810371|
|||T. Schreiber et al., “Stress-induced single-polarization single-transverse mode photonic crystal fiber with low nonlinearity”, Opt. Express 13 (19), 7621 (2005), doi:10.1364/OPEX.13.007621|
|||M.-J. Li et al., “High bandwidth single polarization fiber with elliptical central air hole”, J. Lightwave Technol. 23 (11), 3454 (2005)|
|||J. R. Folkenberg et al., “Broadband single-polarization photonic crystal fiber”, Opt. Lett. 30 (12), 1446 (2005), doi:10.1364/OL.30.001446|
|||X. Chen et al., “Wide band single polarization and polarization maintaining fibers using stress rods and air holes”, Opt. Express 16 (16), 12060 (2008), doi:10.1364/OE.16.012060|
|||K. K. Y. Lee et al., “Design strategies and rigorous conditions for single-polarization single-mode waveguides”, Opt. Express 16 (19), 15170 (2008), doi:10.1364/OE.16.015170|
|||M. Chen and Y. Zhang, “Improved design of polarization-maintaining photonic crystal fibers”, Opt. Lett. 33 (21), 2542 (2008), doi:10.1364/OL.33.002542|