Mode resolved bend loss in few-mode optical fibers.

We present a novel approach to directly measure the bend loss of individual modes in few-mode fibers based on the correlation filter technique. This technique benefits from a computer-generated hologram performing a modal decomposition, yielding the optical power of all propagating modes in the bent fiber. Results are compared with rigorous loss simulations and with common loss formulas for step-index fibers revealing high measurement fidelity. To the best of our knowledge, we demonstrate for the first time an experimental loss discrimination between index-degenerated modes.

[1]  Vladimir S. Pavelyev,et al.  Mode multiplexing by diffractive optical elements in optical telecommunication , 2004, Laser Optics.

[2]  Moty Heiblum,et al.  Analysis of curved optical waveguides by conformal transformation , 1975 .

[3]  D. Courjon,et al.  A versatile and stable device allowing the efficient generation of beams with radial, azimuthal or hybrid polarizations , 2005 .

[4]  Dietrich Marcuse,et al.  Curvature loss formula for optical fibers , 1976 .

[5]  Daniel Flamm,et al.  Wavefront reconstruction by modal decomposition. , 2012, Optics express.

[6]  Fabio Di Teodoro,et al.  Diffraction-limited, 300-kW peak-power pulses from a coiled multimode fiber amplifier. , 2002, Optics letters.

[7]  J. Sakai,et al.  Simplified bending loss formula for single-mode optical fibers. , 1979, Applied optics.

[8]  Thomas Kaiser,et al.  Fast M2 measurement for fiber beams based on modal analysis. , 2012, Applied optics.

[9]  Michael A. Golub,et al.  BRIEF COMMUNICATIONS: Synthesis of spatial filters for investigation of the transverse mode composition of coherent radiation , 1982 .

[10]  Jean-Pierre Berenger,et al.  A perfectly matched layer for the absorption of electromagnetic waves , 1994 .

[11]  D. Gloge,et al.  Bending loss in multimode fibers with graded and ungraded core index. , 1972, Applied optics.

[12]  R. Schermer,et al.  Mode scalability in bent optical fibers. , 2007, Optics express.

[13]  H. Renner,et al.  Bending losses of coated single-mode fibers: a simple approach , 1992 .

[14]  Vladimir S. Pavelyev,et al.  Transverse mode multiplexing by diffractive optical elements , 2005, Optical Technologies for Telecommunications.

[15]  William Primak,et al.  Photoelastic Constants of Vitreous Silica and Its Elastic Coefficient of Refractive Index , 1959 .

[16]  Thomas Kaiser,et al.  Complete modal decomposition for optical fibers using CGH-based correlation filters. , 2009, Optics express.

[17]  G. Scherer,et al.  Stress-induced index profile distortion in optical waveguides. , 1980, Applied optics.

[18]  Daniel Flamm,et al.  Mode analysis with a spatial light modulator as a correlation filter. , 2012, Optics letters.

[19]  J W Nicholson,et al.  Spatially and spectrally resolved imaging of modal content in large-mode-area fibers. , 2008, Optics express.

[20]  Dietrich Marcuse,et al.  Field deformation and loss caused by curvature of optical fibers , 1976 .

[21]  F. Pockels.  Ueber die Aenderung des optischen Verhaltens verschiedener Gläser durch elastische Deformation , 1902 .

[22]  Siddharth Ramachandran,et al.  Natural bend-distortion immunity of higher-order-mode large-mode-area fibers. , 2007, Optics letters.

[23]  W H Lee,et al.  Binary computer-generated holograms. , 1979, Applied optics.

[24]  X. Yuan,et al.  High-volume optical vortex multiplexing and de-multiplexing for free-space optical communication. , 2011, Optics express.

[25]  Giuseppe Martini,et al.  Bend loss in single-mode fibers , 1997 .

[26]  S. Rashleigh,et al.  Bending-induced birefringence in single-mode fibers. , 1980, Optics letters.

[27]  J. Fleming,et al.  Dispersion in GeO 2 –SiO 2 glasses , 1984 .

[28]  A. Harris,et al.  Bend loss measurements on high numerical aperture single-mode fibers as a function of wavelength and bend radius , 1986 .

[29]  L. Goldberg,et al.  Single-mode operation of a coiled multimode fiber amplifier. , 2000, Optics letters.

[30]  D. Marcuse,et al.  Influence of curvature on the losses of doubly clad fibers. , 1982, Applied optics.

[31]  J. Fini.  Bend-resistant design of conventional and microstructure fibers with very large mode area. , 2006, Optics express.

[32]  S Ramachandran,et al.  Cross-correlated (C2) imaging of fiber and waveguide modes. , 2011, Optics express.

[33]  Thomas Kaiser,et al.  Measuring the spatial polarization distribution of multimode beams emerging from passive step-index large-mode-area fibers. , 2010, Optics letters.

[34]  N. Shibata,et al.  Bending loss measurement of LP11 mode in quasi-single-mode operation region , 1985 .

[35]  J. H. Cole,et al.  Improved Bend Loss Formula Verified for Optical Fiber by Simulation and Experiment , 2007, IEEE Journal of Quantum Electronics.