This paper presents a numerical study of high birefringence induced by four types (Type 1&#x2013;4) of different sizes of elliptical air holes in photonic crystal fibers (PCFs). The numerical simulation is carried out by using the finite element method. The statistical correlations between the birefringence and the various parameters are obtained. Based on our results, the birefringence is found to be largely dependent on the variation of the normalized frequency, size ratio, effective area of the circular and elliptical air holes, and the ring number of cladding. Two of our suggested structures, Type 1 and Type 3, can considerably enhance the birefringence in PCFs leading to values as high as <svg     style="vertical-align:-0.20474pt;width:83.8125px;" id="M1" height="16.1" version="1.1" viewBox="0 0 83.8125 16.1" width="83.8125"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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</svg>, respectively, which are much higher than that obtained by a conventional step-index fiber.

Yuan-Fong Chau

Han-Hsuan Yeh

Din Ping Tsai

Analysis of High Birefringence of Four Types of Photonic Crystal Fiber by Combining Circular and Elliptical Air Holes in Fiber Cladding

A newly proposed strong harmonic-expansion method is applied to the laser-Lorenz equations to analytically construct a few typical solutions, including the first few expansions of the well-known period-doubling cascade that characterizes the system in its self-pulsing regime of operation. These solutions are shown to evolve in accordance with the driving frequency of the permanent solution that we recently reported to illustrate the system. The procedure amounts to analytically construct the signal Fourier transform by applying an iterative algorithm that reconstitutes the first few terms of its development.

Belkacem Meziane

Ahmed A&#239;ssani

Analytical Structuring of Periodic and Regular Cascading Solutions in Self-Pulsing Lasers

We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (&gt;10% modulation depth) and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature.

Andreas Schmitt-Sody

Andreas Velten

Ye Liu

Ladan Arissian

Jean-Claude Diels

High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large Tunability

The role of Fermi resonance in formation of valence band of water Raman scattering was investigated. Simultaneous measurement of characteristics of bending and valence bands of water in <svg style="vertical-align:-3.13504pt;width:28.7875px;" id="M1" height="14.6" version="1.1" viewBox="0 0 28.7875 14.6" width="28.7875"  xmlns="http://www.w3.org/2000/svg">
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</svg> solutions, KBr, and KCl and using genetic algorithms in conjunction with variation methods allowed increasing accuracy of estimation of Fermi resonance coupling constant and of Fermi resonance contribution into formation of water Raman valence band.

Sergey A. Burikov

Tatiana A. Dolenko

Victor V. Fadeev

The Role of Fermi Resonance in Formation of Valence Band of Water Raman Scattering

The transmission speed of optical network strongly depends on the impact of higher order dispersion. In presence of coherent crosstalk, which cannot be otherwise controlled by optical filtering, the impact of higher order dispersions becomes more pronounced. In this paper, the general expressions, that describe pulse deformation due to second- and fourth-order dispersions in a single-mode fiber, are given. The responses for such even-order dispersions, in presence of coherent crosstalk, are characterized by waveforms with long trailing edges. The transmission quality of optical pulses, due to both individual and combined influence of second- and fourth-order dispersions, is studied in this paper. Finally, the pulse shape and eye diagrams are obtained.

Aleksandra Panajotovic

Daniela Milovic

Anjan Biswas

Essaid Zerrad

Influence of Even-Order Dispersion on Super-Sech Soliton Transmission Quality under Coherent Crosstalk

The data pulse delay based on slow light induced by stimulated Brillouin scattering (SBS) in a nonuniform dispersion decreasing fiber (DDF) is demonstrated experimentally, and the distortions of data pulses at different beat frequencies are studied. We found that a delay exceeding a pulse width can be achieved at particular beat frequency, and the DDF has larger delay versus gain slope coefficient with much better output pulse quality than single-mode fiber.

Wenhai Li

Xiaoyi Bao

V. P. Kalosha

Liang Chen

Ming-Jun Li

Using Nonuniform Fiber to Generate Slow Light via SBS

Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-clad <svg style="vertical-align:-0.0pt;width:35.424999px;" id="M2" height="13.775" version="1.1" viewBox="0 0 35.424999 13.775" width="35.424999"  xmlns="http://www.w3.org/2000/svg">
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</svg>&#x2009;nm. Varying the output coupling from 96&#x25; to 5&#x25;, the laser wavelength is tuned over a range of 106&#x2009;nm from 1949 to 2055&#x2009;nm. The output power exceeds 20&#x2009;W over 90-nm range and the maximum output power is 32&#x2009;W at 1949&#x2009;nm for 51-W launched pump power, corresponding to a slope efficiency of <svg style="vertical-align:-0.17555pt;width:30.799999px;" id="M4" height="10.9125" version="1.1" viewBox="0 0 30.799999 10.9125" width="30.799999"  xmlns="http://www.w3.org/2000/svg">
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Yulong Tang

Yong Yang

Jianqiu Xu

High Power <svg style="vertical-align:-0.0pt" height="16.475" version="1.1" viewBox="0 0 36.674999 16.475" width="36.674999" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,16.413)"><path id="x54" d="M592 498l-30 -3q-13 63 -31 89q-13 19 -33.5 25.5t-75.5 6.5h-70v-493q0 -60 16 -75.5t86 -19.5v-28h-286v28q68 4 83.5 19.5t15.5 75.5v493h-62q-60 0 -83 -7t-33 -24q-12 -17 -32 -90h-29q10 116 12 180h20q10 -16 21 -20.5t34 -4.5h395q19 0 28.5 5t21.5 20h21&#xA;q2 -89 11 -177z" /></g><g transform="matrix(.017,-0,0,-.017,9.14,16.413)"><path id="x6D" d="M797 0h-214v26q46 5 58 17.5t12 63.5v167q0 116 -88 116q-48 0 -112 -52q3 -18 3 -42v-195q0 -46 11 -58t53 -17v-26h-214v26q48 5 59.5 17t11.5 60v172q0 115 -88 115q-47 0 -109 -52v-235q0 -47 10 -59.5t48 -17.5v-26h-211v26q50 5 62.5 17t12.5 60v207q0 48 -9 59.5&#xA;t-52 18.5v23q79 14 139 41v-81q3 2 29 20.5t44 29.5q45 28 81 28t66 -22t46 -61q25 20 83 57q39 26 76 26q59 0 93 -40t34 -113v-193q0 -49 10.5 -60.5t54.5 -16.5v-26z" /></g><g transform="matrix(.012,-0,0,-.012,23.063,8.25)"><path id="x1D7D1" d="M58 524l-21 12q80 152 229 152q73 0 119 -41q45 -41 45 -96q0 -40 -21.5 -74.5t-62.5 -52.5q57 -20 89.5 -68.5t32.5 -109.5q0 -110 -86 -185t-214 -75q-69 0 -110.5 24.5t-41.5 65.5q0 26 18.5 43t46.5 17q45 0 96 -57q39 -43 79 -43q45 0 71.5 34t26.5 88q0 75 -49 121&#xA;q-25 23 -56 39q-34 17 -97 38v17q69 21 100 53t31 78q0 103 -99 103q-40 0 -69.5 -19t-56.5 -64z" /></g><g transform="matrix(.012,-0,0,-.012,29.012,8.25)"><path id="x2B" d="M535 230h-212v-233h-58v233h-213v50h213v210h58v-210h212v-50z" /></g></svg>-Doped Fiber Lasers Tuned by a Variable Reflective Output Coupler

This paper presents a numerical study of parabolic pulse generation in tapered microstructured optical fibres (MOFs). Based on our results and the algorithms presented, one can determine the linear taper profile (starting and finishing pitch values and taper length) needed to achieve parabolic pulse shaping of an initial Gaussian pulse shape with different widths and powers. We quantify the evolution of the parabolic pulse using the misfit parameter and show that it is possible to reach values significantly better than those obtained by a step index fibre.

Natasha Vukovic

Neil G. R. Broderick

Francesco Poletti

Parabolic Pulse Generation Using Tapered Microstructured Optical Fibres

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<p><em>International Journal of Optics</em> publishes both fundamental and highly applied studies on the nature of light, its properties and behaviours, and its interaction with matter.</p>


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<p>Chief Editor, Professor Cerullo, leads the Ultrafast Spectroscopy group at the Department of Physics at the Polytechnic University of Milan. His research activity has mainly focused on the physics and applications of ultrashort pulse lasers.</p>


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International Journal of Optics - Table of contents 2008

International Journal of Optics | Hindawi

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International Journal of Optics publishes both fundamental and highly applied studies on the nature of light, its properties and behaviours, and its interaction with matter.

International Journal of Optics