Elzbieta M. Beres-Pawlik

Photonic Crystal Fiber With Large Mode Area and Characteristic Bending Properties

We report on a photonic crystal fiber with a large mode area designed for compact high power fiber lasers and amplifiers. The fiber suppresses higher order modes when bent around a 10-cm radius and enables single mode operation in small footprint laser and amplifier architectures. We experimentally confirm the peculiar bending properties of this fiber in its passive version, by reporting on the measurement results of fundamental mode loss in bent and straight fibers, and of the influence of the bending plane orientation on this fiber loss.

Mid-infrared emission in Tb 3+ -doped selenide glass fiber

The mid-infrared (MIR) emission behavior of Tb3+-doped Ge–As–Ga–Se bulk glasses (500, 1000, and 1500 ppmw Tb3+) and unstructured fiber (500 ppmw Tb3+) is investigated when pumping at 2.013 μm. A broad emission band is observed at 4.3–6.0 μm corresponding to F57→F67, with an observed emission lifetime of 12.9 ms at 4.7 μm. The F47 level is depopulated nonradiatively and so it is proposed that Tb3+-doped Ge–As–Ga–Se fiber may operate as a quasi-three-level MIR fiber laser. Underlying glass-impurity vibrational absorption bands are numerically removed to give the true Tb3+ absorption cross section, as required for Judd–Ofelt (J–O) analysis. Radiative transition rates calculated from J–O theory are compared with measured lifetimes. A numerical model of the three-level Tb3+-doped fiber laser is developed for Tb3+ doping of 8.25×1024  ions m−3 (i.e., 500 ppmw) and dependence of laser performance on fiber length, output coupler reflectivity, pump wavelength, signal wavelength, and fiber background loss is calculated. Results indicate the feasibility of an efficient three-level MIR fiber laser operating within 4.5–5.3 μm, pumped at either 2.013 or 2.95 μm.

Passive Multimode Fibre Optic Structures

The paper presents possibilities to use multimode network structures in commercial applications

Modelling of chalcogenide glass fibre lasers for MIR generation

The presentation gives an account of recent developments in the modelling of chalcogenide glass based lanthanide doped fibre lasers for the mid-infra-red (MIR) wavelength range. The particular lanthanide elements considered include dysprosium, praseodymium and terbium. Both classical 3 level lasing systems and cascade lasing systems are considered, and their properties compared. Steady state and pulsed operation of the lasers is considered and the possible application as a seed pump for supercontinuum generation is discussed. Several aspects of numerical methods used specifically for the modelling of MIR fibre lasers are also considered.

Realization of the stream comparison mechanism in a CSMA/CD type multimode passive optical network node — experiments

In this paper we show and describe the experimental results obtained in the symmetrical, multimode passive optical network with the use of network nodes described in details in [1]. We prove that it is feasible to construct a simple and efficient passive optical network working with the use of CSMA/CD mechanism and that it is possible to construct such a network from a standard, easy to buy components. In the designed and tested network 850 nm VCSEL transceivers were used.

Polarization-maintaining erbium doped photonic crystal fiber laser

A polarization maintaining erbium-doped photonic crystal fiber laser (PM-Er-PCF), is presented. The laser operates in a ring cavity in the near infrared wavelength range. We believe that it is the first report of the successful realization of a polarization maintaining erbium-doped photonic crystal fiber laser. Single-wavelength and multiwavelength operation of the developed fibre laser was observed. Experimental results show that the laser operates with good output parameter stability over a period of one hour and exhibits a 37 dB signal-to-noise-ratio. We present a detailed description of the design process and of the experimental characterization and validation for the PM-Er-PCF. We also analyze the impact of the photonic crystal structure on the laser parameters.

Analysis of pumping efficiency of side coupling method in double-clad fibers doped with rare earth ions

A method of pumping lasers built on the basis of double-clad neodymium-ion doped fibers is presented in the paper. Couplings were realized by asymmetrical couplers built with a multimode PCS (pumping) fiber and a double-clad (pumped) fiber. Special software for designing such asymmetrical couplers was elaborated. It allows us to choose appropriate parameters of the couplers components, enabling to obtain a maximum pumping power, introduced by the purpose-built coupler.

EDF laser with double-Bragg grating selection

We present a new configuration of ring erbium doped fiber laser with specific way of wavelength selection. The fiber circulator with a novel configuration of two Bragg gratings was applied. The wavelength selectivity of the ring laser can be substantially improved when the transmission characteristics of both gratings are partly overlapped. Additional element improving the stability of the laser can be obtained when its state of polarization is controlled.

Determination of Possibilities of SI Plastic Fiber Application in Passive Optical Network

The main objectives of this paper is to improve knowledge of multimode fiber transmission over step-index plastic optical fiber SI POF with 1000 Lim core. The thick SI POF fibers seem a very attractive alternative in local computer networks for the “classic” (thin) single- and multimode fibers because of their low price and easy installation. In the paper we show measurements of bandwidth and attenuation of various SI POF optical paths. In particular, there was investigated a cascade of passive components (couplers, patchcords) which can be part of transparent (passive) optical networks.

Methods of Building Ethernet-type Passive Optical Networks

This paper presents three methods of constructing Ethernet-type passive optical networks. A novel construction of the symmetric optical networks based on a transmissive star structure is presented. Collision detection method used in copper Ethernet networks, CSMA/CD, was slightly modified to accommodate the differences between the passive optical networks and copper network.