Gamma-shaped long-cavity normal-dispersion mode-locked Er-fiber laser for sub-nanosecond high-energy pulsed generation

We propose the design of a novel ?-shaped fiber laser resonator and apply it to build a long-cavity normaldispersion mode-locked Er-fiber laser which features enhanced functionalities for management and optimization of pulsed lasing regimes. We report the generation of sub-nanosecond pulses with the energy of ~0.5 µJ at a kilohertz-scale repetition rate in an all-fiber system based on the new laser design. A combination of special design solutions in the laser, such as polarization instability compensation in the ultra-long arm of the resonator, intra-cavity spectral selection of radiation with a broadband fiber Bragg grating, and polarization selection by means of a tilted refractive index grating, ensures low amplified spontaneous emission (ASE) noise and high stability of the laser system output parameters.

Ultra-long mode-locked Er-droped fibre lasers

The development of ultra-long (UL) cavity (hundreds of meters to several kilometres) mode-locked fibre lasers for the generation of high-energy light pulses with relatively low (sub-megahertz) repetition rates has emerged as a new rapidly advancing area of laser physics. The first demonstration of high pulse energy laser of this type was followed by a number of publications from many research groups on long-cavity Ytterbium and Erbium lasers featuring a variety of configurations with rather different mode-locked operations. The substantial interest to this new approach is stimulated both by non-trivial underlying physics and by the potential of high pulse energy laser sources with unique parameters for a range of applications in industry, bio-medicine, metrology and telecommunications. It is well known, that pulse generation regimes in mode-locked fibre lasers are determined by the intra-cavity balance between the effects of dispersion and non-linearity, and the processes of energy attenuation and amplification. The highest per-pulse energy has been achieved in normal-dispersion UL fibre lasers mode-locked through nonlinear polarization evolution (NPE) for self-modelocking operation. In such lasers are generated the so-called dissipative optical solitons. The uncompensated net normal dispersion in long-cavity resonatorsusually leads to very high chirp and, consequently, to a relatively long duration of generated pulses. This thesis presents the results of research Er-doped ultra-long (more than 1 km cavity length) fibre lasers mode-locked based on NPE. The self-mode-locked erbium-based 3.5-km-long all-fiber laser with the 1.7 µJ pulse energy at a wavelength of 1.55 µm was developed as a part of this research. It has resulted in direct generation of short laser pulses with an ultralow repetition rate of 35.1 kHz. The laser cavity has net normal-dispersion and has been fabricated from commercially-available telecom fibers and optical-fiber elements. Its unconventional linear-ring design with compensation for polarization instability ensures high reliability of the self-mode-locking operation, despite the use of a non polarization-maintaining fibers. The single pulse generation regime in all-fibre erbium mode-locking laser based on NPE with a record cavity length of 25 km was demonstrated. Modelocked lasers with such a long cavity have never been studied before. Our result shows a feasibility of stable mode-locked operation even for an ultra-long cavity length. A new design of fibre laser cavity – “y-configuration”, that offers a range of new functionalities for optimization and stabilization of mode-locked lasing regimes was proposed. This novel cavity configuration has been successfully implemented into a long-cavity normal-dispersion self-mode-locked Er-fibre laser. In particular, it features compensation for polarization instability, suppression of ASE, reduction of pulse duration, prevention of in-cavity wave breaking, and stabilization of the lasing wavelength. This laser along with a specially designed double-pass EDFA have allowed us to demonstrate anenvironmentally stable all-fibre laser system able to deliver sub-nanosecond high-energy pulses with low level of ASE noise.

Gamma-shaped long-cavity normal-dispersion mode-locked Er-fiber laser for sub-nanosecond high-energy pulsed generation

We propose the design of a novel ?-shaped fiber laser resonator and apply it to build a long-cavity normaldispersion mode-locked Er-fiber laser which features enhanced functionalities for management and optimization of pulsed lasing regimes. We report the generation of sub-nanosecond pulses with the energy of ~0.5 µJ at a kilohertz-scale repetition rate in an all-fiber system based on the new laser design. A combination of special design solutions in the laser, such as polarization instability compensation in the ultra-long arm of the resonator, intra-cavity spectral selection of radiation with a broadband fiber Bragg grating, and polarization selection by means of a tilted refractive index grating, ensures low amplified spontaneous emission (ASE) noise and high stability of the laser system output parameters.

Optimisation of microstructured waveguides in z-cut LiNbO3 crystals

We present a practical approach to the numerical optimisation of the guiding properties of buried microstructured waveguides, which can be fabricated in a z-cut lithium niobate (LiNbO3) crystal by the method of direct femtosecond laser inscription. We demonstrate the possibility to extend the spectral range of low-loss operation of the waveguide into the mid-infrared region beyond 3um.

Microstructured waveguides in z-cut LiNbO3 by high-repetition rate direct femtosecond laser inscription

We report on the operational parameters that are required to fabricate buried, microstructured waveguides in a z-cut lithium niobate crystal by the method of direct femtosecond laser inscription using a highrepetition-rate, chirped-pulse oscillator system. Refractive index contrasts as high as −0.0127 have been achieved for individual modification tracks. The results pave the way for developing microstructured WGs with low-loss operation across a wide spectral range, extending into the mid-infrared region up to the end of the transparency range of the host material.

Control of the properties of micro-structured waveguides in LiNbO3 fabricated by direct femtosecond laser inscription

This paper reports on buried waveguides fabricated in lithium niobate (LN) by the method of direct femtosecond (fs) laser inscription. 5% MgO doped LiNbO3 was chosen as the host material because of its high quality and damage threshold, as well as relatively low cost. Direct fs inscription by astigmatically shaped beam in crystals usually produces multiple 'smooth' tracks (with reduced refractive index), which encircle the light guiding 'core', thus creating a depressed cladding WG. A high-repetition rate fs laser system was used for inscription at a depth of approximately 500 μm. Using numerical modelling, it was demonstrated that the properties of fs-written WGs can be controlled by the WG geometry. Buried, depressed-cladding WGs in LN host with circular cross-section were also demonstrated. Combining control over the WG dispersion with quasi-phase matching will allow various ultralow-pump-power, highly-efficient, nonlinear light-guiding devices - all in an integrated optics format.

Stable dual-wavelength oscillation of an Er-doped fiber ring laser at room temperature

We propose a simple Er-doped fiber laser configuration for achieving stable dual-wavelength oscillation at room temperature, in which a high birefringence fiber Bragg grating was used as the wavelength-selective component. Stable dual-wavelength oscillation at room temperature with a wavelength spacing of 0.23 nm and mutually orthogonal polarization stages was achieved by utilizing the polarization hole-burning effect. An amplitude variation of less than 0.7 dB over an 80 s period was obtained for both wavelengths.

'Er's from off:the indexicalization and enregisterment of Black Country dialect

This article considers how conscious use of dialect in writing is an intentional act and can be accounted for through the notion of enregisterment. It does this by exploring the value of dialect in social and ideological contexts in relation to a regional dialect of British speech, that of the Black Country in the West Midlands region of England. The article provides a summary of recent directions in sociolinguistic research and an overview of the Black Country speech community, including a summary of its distinctive linguistic variables. This description is then used as an external evaluation of the authenticity of written representations of Black Country speech and the items enregistered in writing. Analysis of three written texts taken from three different genres across a time span of 30 years reveals the extent to which identified linguistic features are drawn upon in each one of the three texts and the extent to which any one is enregisterd across all three. The article discusses the social and linguistic contexts within which the writing occurs by way of accounting for their enregisterment as markers of identity linked to region and place. It also considers the ways in which the texts juxtapose norms and values of those "within" the community with those from "outside" the community in ways that subvert traditional notions of linguistic hierarchy.

A regionális árampiaci integráció hatása az erőművek piaci erőfölényére

Tanulmányunkban a közép- és kelet-európai térség villamosenergia-nagykereskedelmi piacának rövid távú közgazdasági modellezésével foglalkozunk - teljes piacnyitás utáni körülményeket feltételezve. A modell inputjai között becslést adunk az igénybe vehető termelőkapacitások nagyságára és a termelés költségére, a keresleti jellemzőkre és az átviteli hálózat sajátosságaira. Modellezési megközelítésünk előnye, hogy egyszerre vesszük figyelembe a regionális piacok egymáshoz való térbeli viszonyát és a piaci erőfölénnyel rendelkező vállalatok árbefolyásoló képességét. Főbb következtetéseink: 1. a jelenlegi piaci integráció szintjén a nagy áramtermelő vállalatok piaci ereje számottevő; 2. a szorosabb piaci integráció mérsékli az erőfölénnyel való visszaélés lehetőségét, és árcsökkentő hatással jár; viszont 3. a teljes piaci integráció sem korlátozza kielégítő módon a nagy áramtermelők piaci erejét. Modellezési eredményeink gyakorlati jelentőségét azonban egyszerűsítő feltevéseink valószínűségnek vizsgálata nélkül nem tudjuk pontosan megítélni.

Emberi erőforrás menedzsment és gyakorlatai a lean termelésben – a tevékenységmenedzsment irodalmának tükrében = Human resource management and practices in lean manufacturing – review of Operations Management’s literature

A lean bevezetése nem korlátozódik a termelés újraértelmezésére, hanem jellemzően a vállalati belső működés (számvitel, emberi erőforrás, beszerzés) és külső kapcsolatok (beszállítók, ellátási lánc) újszervezését is megköveteli. Ezek a kapcsolódási pontok számos, tudományterületek határán fekvő kutatási irányt nyitnak meg. Ebben a tanulmányban a lean termelés és a belső működéshez sorolt emberi erőforrás menedzsment kapcsolatára fókuszálok. Célom, hogy a tevékenységmenedzsment vonatkozó irodalmának áttekintésével bemutassam a lean termelés logikájához illeszkedő emberi erőforrás menedzsmentet, annak jellemző gyakorlatait. = Lean goes beyond manufacturing, implementing its principles usually requires companies to reorganize their companywide internal operations (accounting, human resource, purchasing) and also external relations (supplier, supply chain). This linkages offer several multidisciplinary research directions, this study focuses on the relationship between human resource management and lean production. The main aim of this working paper is to review Operations Management’s literatures on this issue and present the human resource policy and its practices that fit and support lean production.

Információs társadalom és humán erőforrás fejlesztés - magyar közpolitikák szembesítése egy közép-európai lakossági felmérés eredményeivel

2003 januárjában tíz közép-európai országban reprezentatív lakossági felmérés készült az információs társadalom témájában. A dolgozat a felmérés eredményeit szembesíti a magyar kormányzat három különböző, de egymással a humán erőforrás fejlesztési feladatok kapcsán összefüggő közpolitikájának céljaival és tetteivel. Az informatikai politika, valamint az oktatásügyi és munkaügyi politika informatikai vonatkozásai sokban hozzájárultak ahhoz, hogy az információs társadalom magyar jelzőszámai részben megfelelnek a közép-európai átlagnak, részben pedig elmaradást tükröznek attól.

A marketing-erőforrások hatások a vállalati versenyképességre (The impact of marketing resources to corporate competitiveness)

A tanulmány a marketing-erőforrások és a vállalatok versenyképessége közötti összefüggéseket elemzi és hasonlítja össze az öt évvel korábbi felmérés eredményeivel. A háromszáz hazai vállalatra kiterjedő kutatás során a szerzők azt állapították meg, hogy a vizsgált marketing-erőforrások mindegyike hatással van a vállalati teljesítményre. Ez annyiban jelent változást az öt évvel korábbi eredményekhez képest, hogy akkor a marketingképességek szerepe még nem volt egyértelmű. Az elemzés során kimutatták, hogy a vállalatok által birtokolt marketing-erőforrások hasonló struktúrát mutatnak, mint korábban. Ezek közül kiemelkedik a marketingfunkcióhoz leginkább köthető piacszervezési dimenzió, amely a legszorosabb összefüggést mutatja a versenyképességgel. A vizsgált vállalatok egy kis csoportjának (12%) sikerült a versenyképes termékkínálat és árak fenntartása mellett e képesség kifejlesztésében és birtoklásában előre lépniük. Körükben a sikeres vállalatok aránya kiemelkedő. / === / The study aimed to analyse the association between marketing resources and corporate competitiveness and it compared the results to the ones of a similar research conducted five years before. Based on the survey of 300 domestic organisations the authors found that all the marketing resources investigated have a significant effect on marketing performance. These results differ from the previous ones only in terms of marketing capabilities, as their role was ambiguous at that time. They revealed the same structure of marketing resources owned by the companies as last time. Among them the most marketing related resource-dimension called market management excels regarding the strength of the association with competitiveness. A small group of the companies investigated (12%) managed to advance in development and possession of this dimension of marketing resources whilst maintaining competitive product supply and price. The proportion of successful companies among them is highly significant