Mode Area Photonic Crystal Fiber Research Articles

Infrared supercontinuum from a large mode area PCF under extreme picosecond excitation

Evolution of the long-wavelength edge of supercontinuum (SC) in a large mode-area photonic crystal fiber (LMA PCF) under extreme (close to the fiber damage threshold) picosecond excitation is analyzed for the first time to our knowledge. The obtained results are interpreted on the basis of the numerical simulations explaining both spectral and temporal characteristics of SC in dependence on the pulse power and the fiber length. An existence of the minimum LMA PCF length providing the broadest spectrum under the highest picosecond excitations is predicted. The multimode cross-modulation inside the LMA PCF is analyzed, as well.

Single-modeness of short large mode area fibers: An experimental study

We experimentally investigated the limits to the endlessly single-modeness of large mode area photonic crystal fibers. We analyzed two versions of a commercial large mode area fiber with equal structural parameters but five or seven confining rings, and in both cases we found that the single mode regime becomes critical for short (<1 m) lengths. In these cases we report on the excitation of a second-order mode, whose microphotographed structure is very well reproduced by the results of numerical simulations. The multimodal behavior is further confirmed by polarization measurements. Also we found that the single-modeness is maintained in longer (>1 m) fibers. The same results were observed in large mode area fibers with different core sizes.

Experimental investigations of bending loss oscillations in large mode area photonic crystal fibers

We demonstrate experimentally that bending loss in large mode area photonic crystal fibers oscillates with wavelength. To do so we carried out loss measurements for different fiber bend radii and for different angular orientations. These results confirm the oscillatory behavior of bending loss vs. wavelength as predicted recently by numerical analysis [J. Olszewski et al., Opt. Express 13, 6015 (2005)]. We also found good agreement between our measurement results and our simulations relying on a finite element method with perfectly matched layers and an equivalent index model.

Highly sensitive long-period fiber-grating strain sensor with low temperature sensitivity

A long-period fiber-grating sensor with a high strain sensitivity of -7.6 pm/microepsilon and a low temperature sensitivity of 3.91 pm/ degrees C is fabricated by use of focused CO(2) laser beam to carve periodic grooves on a large- mode-area photonic crystal fiber. Such a strain sensor can effectively reduce the cross-sensitivity between strain and temperature, and the temperature-induced strain error obtained is only 0.5 microepsilon/ degrees C without using temperature compensation.

The Optimum Fusion Splicing Conditions for a Large Mode Area Photonic Crystal Fiber

We report the empirically obtained conditions for the fusion splicing with photonic crystal fibers (PCF) having large mode areas. By controlling the arc-power and the arc-time of a conventional electric-arc fusion splicer, the splicing loss between two PCFs could be lowered down to 0.2 dB in average. For the splicing PCF with a conventional single mode fiber (SMF), the loss was increased due to the modal field mismatch, but still below 0.45 dB in average. The tensile strength was weakened by the splicing from 2.83 GPa down to 1.04 GPa for the PCF-PCF case and 0.89 GPa for the PCF-SMF one.

Stress-induced single-polarization single-transverse mode photonic crystal fiber with low nonlinearity

We report on the design of a single-polarization single-transverse mode large mode area photonic crystal fiber. By including index-matched stress applying elements in the photonic cladding an ultra-broadband single polarization window is obtained while a large mode field area of ~700 microm(2) is maintained. Based on that design, an Yb-doped double-clad photonic crystal fiber is realized that combines low nonlinearity and single polarization properties. A first result of the high power operation using this fiber is demonstrated.

Experimental research on mode properties of large mode area photonic-crystal fiber laser

A large-mode-area double-cladding Yb3+-doped photonic-crystal fiber laser (PCFL) is constructed. The laser's intensity distribution and polarization states are measured with three different PCF macrobending radii R. The experiment shows that when R is large enough, the multitransverse mode appears and becomes increasingly more obvious with the increase of pump power Pp. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 141–144, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20925

Polarization maintaining large mode area photonic crystal fiber

We report on a polarization maintaining large mode area photonic crystal fiber. Unlike, previous work on polarization maintaining photonic crystal fibers, birefringence is introduced using stress applying parts. This has allowed us to realize fibers, which are both single mode at any wavelength and have a practically constant birefringence for any wavelength. The fibers presented in this work have mode field diameters from about 4 to 6.5 micron, and exhibit a typical birefringence of 1.510(-4).

Predicting macrobending loss for large-mode area photonic crystal fibers

We report on an easy-to-evaluate expression for the prediction of the bend-loss for a large mode area photonic crystal fiber (PCF) with a triangular air-hole lattice. The expression is based on a recently proposed formulation of the V-parameter for a PCF and contains no free parameters. The validity of the expression is verified experimentally for varying fiber parameters as well as bend radius. The typical deviation between the position of the measured and the predicted bend loss edge is within measurement uncertainty.

Polarization-mode dispersion of large mode-area photonic crystal fibers

We report on an experimental study of the polarization properties of large mode-area photonic crystal fibers (PCFs). We find that such fibers may exhibit very low birefringence and polarization-mode dispersion (PMD) indicating a highly symmetrical hole structure over a long length. Moreover, the influence of temperature on the polarization-mode dispersion is investigated. The results show that it is possible to fabricate photonic crystal fibers with polarization-mode dispersion, which is nearly insensitive to changes in temperature.

40 Gbit∕s transmission over photonic crystal fibre using mid-span spectral inversion in highly nonlinear photonic crystal fibre

Transmission at 40 Gbit/s over large mode area photonic crystal fibre (PCF) together with dispersion compensation by optical phase conjugation in a highly nonlinear PCF are demonstrated for the first time.