High numerical aperture in multimode microstructured optical fibers.

Microstructured or "air-clad" fibers, with air holes surrounding a large core, have recently demonstrated much wider light-acceptance angles than conventional fibers. An original and accurate method is presented for determining the numerical aperture of such fibers using leaky modes. The dependence on length, wavelength, and various microstructure dimensions are evaluated for the first time for a class of fibers that exhibit exceptionally high numerical apertures. These results show excellent agreement with published measurements on similar fibers and verify that bridge thicknesses much smaller than the wavelength are required for high numerical apertures.

[1]  J Broeng,et al.  Multi-mode photonic crystal fibers for VCSEL based data transmission. , 2003, Optics express.

[2]  G. Bouwmans,et al.  High power Er/Yb fiber laser with very high numerical aperture pump cladding waveguide , 2003, 2003 Conference on Lasers and Electro-Optics Europe (CLEO/Europe 2003) (IEEE Cat. No.03TH8666).

[3]  R. J. Potter.  Transmission Properties of Optical Fibers , 1961 .

[4]  J. Broeng,et al.  Numerical aperture of single-mode photonic crystal fibers , 2002, IEEE Photonics Technology Letters.

[5]  G. Stewart.  Optical Waveguide Theory , 1983, Handbook of Laser Technology and Applications.

[6]  G. Bouwmans,et al.  High power air-clad photonic crystal fibre laser. , 2003, Optics express.

[7]  J. A. Buck,et al.  Fundamentals of optical fibers , 1995 .

[8]  Leaky modes on a dielectric waveguide: orthogonality and excitation. , 1976, Applied optics.

[9]  Kazuaki Sakoda,et al.  Optical Properties of Photonic Crystals , 2001 .

[10]  G. Bouwmans,et al.  Very high numerical aperture fibers , 2004, IEEE Photonics Technology Letters.

[11]  Patrick Achenbach,et al.  Computational studies of light acceptance and propagation in straight and curved multimodal active fibres , 2002 .

[12]  J. Gordon,et al.  Light leakage in optical fibers: experimental results, modeling and the consequences for solar concentrators , 2002 .

[13]  Cyril C. Renaud,et al.  Jacketed air-clad cladding pumped ytterbium-doped fibre laser with wide tuning range , 2001 .

[14]  Leon Poladian,et al.  Vector wave expansion method for leaky modes of microstructured optical fibers , 2003 .

[15]  R. L. Gallawa.  On the Definition of Fiber Numerical Aperture , 1982 .

[16]  J. Price,et al.  Cladding pumped Ytterbium-doped fiber laser with holey inner and outer cladding. , 2001, Optics express.

[17]  J. Limpert,et al.  Thermo-optical properties of air-clad photonic crystal fiber lasers in high power operation. , 2003, Optics express.