Geometrical study of a hexagonal lattice photonic crystal fiber for efficient femtosecond laser grating inscription.

We have studied transverse propagation of femtosecond pulse duration laser light through the microstructure of hexagonal lattice photonic crystal fibers. Our results provide insight in the role of the microstructure on the amount of optical power that reaches the core of the PCF, which is of particular importance for grating inscription applications. We developed a dedicated approach based on commercial FDTD software and defined a figure of merit, the transverse coupling efficiency, to evaluate the coupling process. We analyzed the propagation of femtosecond laser pulses to the core of a wide range of PCFs and studied the influence of the PCF orientation angle, the air hole pitch and air hole radius on the energy reaching the core. We have found that the transverse coupling efficiency can benefit from a dedicated design of the microstructured cladding and an accurate fiber orientation. We designed a dedicated PCF microstructure that enhances transverse coupling to the core at a wavelength of 800 nm.

[1]  P. Russell.  Photonic Crystal Fibers , 2003, Science.

[2]  Hugo Thienpont,et al.  Extremely large-mode-area photonic crystal fibre with low bending loss. , 2010, Optics express.

[3]  Fuyun Lu,et al.  Stable and uniform dual-wavelength erbium-doped fiber laser based on fiber Bragg gratings and photonic crystal fiber. , 2005, Optics express.

[4]  John Canning,et al.  Rotationally Variant Grating Writing in Photonic Crystal Fibres , 2009 .

[5]  T A Birks,et al.  Structural long-period gratings in photonic crystal fibers. , 2002, Optics letters.

[6]  H. Bartelt,et al.  Fiber Bragg Gratings in Germanium-Doped Highly Birefringent Microstructured Optical Fibers , 2008, IEEE Photonics Technology Letters.

[7]  Hugo Thienpont,et al.  Highly birefringent microstructured fibers with enhanced sensitivity to hydrostatic pressure. , 2010, Optics express.

[8]  H. Bartelt,et al.  Response of FBGs in Microstructured and Bow Tie Fibers Embedded in Laminated Composite , 2009, IEEE Photonics Technology Letters.

[9]  Hugo Thienpont,et al.  Bragg Grating Inscription in GeO $_2$-Doped Microstructured Optical Fibers , 2010, Journal of Lightwave Technology.

[10]  J. Dudley,et al.  Supercontinuum generation in photonic crystal fiber , 2006 .

[11]  Wim De Waele,et al.  Transversal Load Sensing With Fiber Bragg Gratings in Microstructured Optical Fibers , 2009, IEEE Photonics Technology Letters.

[12]  Hartmut Bartelt,et al.  Fiber Bragg grating inscription combining DUV sub-picosecond laser pulses and two-beam interferometry. , 2008, Optics express.

[13]  David N. Nikogosyan,et al.  Multi-photon high-excitation-energy approach to fibre grating inscription , 2006 .

[14]  Stavros Pissadakis,et al.  Investigations on the Bragg grating recording in all-silica, standard and microstructured optical fibers using 248 nm 5 ps, laser radiation , 2009 .

[15]  S. Mihailov,et al.  Formation of Type I-IR and Type II-IR gratings with an ultrafast IR laser and a phase mask. , 2005, Optics express.

[16]  Thomas D.P. Allsop,et al.  Scattering of the laser writing beam in photonic crystal fibre , 2010 .

[17]  K. Hill,et al.  Fiber Bragg grating technology fundamentals and overview , 1997 .

[18]  Gilberto Brambilla,et al.  Two-photon photochemical long-period grating fabrication in pure-fused-silica photonic crystal fiber. , 2006, Optics letters.

[19]  Michael J Withford,et al.  Transverse coupling to the core of a photonic crystal fiber: the photo-inscription of gratings. , 2007, Optics express.

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

[21]  I. Bennion,et al.  Direct writing of fibre Bragg gratings by femtosecond laser , 2004 .

[22]  T. Strasser,et al.  Grating resonances in air-silica microstructured optical fibers. , 1999, Optics letters.

[23]  D. Grobnic,et al.  Femtosecond IR laser fabrication of Bragg gratings in photonic crystal fibers and tapers , 2006, IEEE Photonics Technology Letters.

[24]  Hugo Thienpont,et al.  Point-by-point fiber Bragg grating inscription in free-standing step-index and photonic crystal fibers using near-IR femtosecond laser. , 2010, Optics letters.

[25]  Jens Kobelke,et al.  Fiber Bragg grating inscription in pure-silica and Ge-doped photonic crystal fibers. , 2009, Applied optics.

[26]  John Canning,et al.  Gratings in structured optical fibres , 2008 .

[27]  Nemanja Jovanovic,et al.  Point-by-point written fiber-Bragg gratings and their application in complex grating designs. , 2010, Optics express.