OJMetalOpen Journal of Metal2164-2761Scientific Research Publishing10.4236/ojmetal.2013.34010OJMetal-40769ArticlesChemistry&Materials Science The Comparative Study of the Temperature Distribution of Fiber Laser with Different Pump Schemes ostafaAbouricha1*AbdelkaderBoulezhar1NabilHabiballah2*Chouaib Doukkali University, Faculty of Science, Laboratory of Condensed Matter of Physics, El Jadida, MoroccoHassan II Casablanca University, Faculty of Sciences-Ain Chok, Laboratory of Theoretical and Applied Physics, Casablanca, Morocco* E-mail:mmabouricha@yahoo.fr(OA);n.habib1980@gmail.com(NH);1312201303046471August 6, 2013September 6, 2013 October 13, 2013© Copyright 2014 by authors and Scientific Research Publishing Inc. 2014This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/

Based on the structure of the long fiber laser (YDCFLs) with different pump schemes using high pump power, the nonlinear coupled and heat dissipation equations are solved numerically. Using the finite-difference method, we have determined the temperature distribution along the radial and axial directions of the fiber laser (YDCFLs) for the forward pump schemes of 200 W with reflection Rp2, backward pump schemes of 200 W with reflection Rp1 and for bidirectional pump scheme of 100 W each side. The results are: the temperature distribution for bidirectional pump mode is more even than that for forward pump with reflection Rp2 and than that for backward pump with reflection Rp1. The results show that the maximum temperature difference between different schemes is 57.51°C, and when the air-clad width decreases, the temperature in the core regions also decreases and does not affect to the cladding radius regions. We summarize that the temperature in the core and in cladding radius regions decreases when the outer radius cladding increases.

Pump Scheme; High Power Fiber Laser; Temperature Distribution1. Introduction

The double-clad fiber laser (DCFLs) have several applications in modern telecommunication, medical instruments, military, defense and material surface processing, because of some unique advantages including high conversion efficiency, excellent beam quality, less thermal effect [1-3]. The continuous wave emission up to kWlevel has been reported [4,5]. A new type of photonic crystal fibers (PCFs) has opened numerous axes in research; this is due to its unique properties such as endlessness.

Thermal effect in Single mode guiding in high-power fiber laser has attracted much attention in recent days [6, 7]. Also, the developments of cladding-pumped fiber technology and high brightness semiconductor diode pump lasers enabled have been used to save energy [8]. The evolution of the temperature and the influence of the core, inner-clad, air-clad and outer clad, on the shape of optical fiber have been studied [9].

Numerically, Shang [8] has investigated the output power characteristics of YDCFLS with different pump schemes, finding the bidirectional pump scheme is compatible with the backward with Rp1 = 0 and forward pump scheme with Rp2 = 0. However, the backward pumped YDCFL with Rp1 = 0.98 has the highest conversion efficiency; while the forward pumped YDCFL with Rp2 = 0.98 has maximum output power per meter.

In this paper, we have investigated numerically the theoretical and numerical analysis of 2D Temperature field by solving the transient heat conduction equations comparing in detail the temperature distributions in the backward pump schemes with Rp1, forward pump schemes with Rp2 and bidirectional pump scheme. The results show that the maximum temperature in the two-end pump is 96.89˚C, in the forward pump is 148.4˚C and in the backward pump is 154.4˚C. Thus, the temperature distributions for two-end pump mode is more even than that for forward pump with reflection Rp2 = 0.98 and backward pump with reflection Rp1 = 0.98 mode.

2. Theoretical Analysis

Figure 1 demonstrates the schematic of YDCFL. For the convenience of analysis, the pump light and output laser

ReferencesJ. Limpert, A. Liem, H. Zellmer and A. Tunnerman, “500 W Continuous-Wave Fiber Laser with Excellent Beam Quality,” Electronics Letters, Vol. 39, No. 8, 2003, pp. 645-647. http://dx.doi.org/10.1049/el:20030447Y. Wang and C.-Q. Xu, “Modeling and Optimization of Q-Switched Double-Clad Fiber Laser,” Applied Optics, Vol. 45, No. 9, 2006, pp. 2058-2071.R. Paschotta, J. Nilsson, A. C. Tropper and D. C. Hanna, “Ytterbium-Doped Fiber Amplifiers,” IEEE Journal of Quantum Electronics, Vol. 33, No. 7, 1997, pp. 1049-1056. http://dx.doi.org/10.1109/3.594865Y. Jeong, J. K. Sahu, D. N. Payne, et al., “Ytterbium- Doped Large-Core Fiber with 1.36 KW of Continuous- Wave Output Power,” Optics Express, Vol. 12, No. 25, 2004, pp. 6088-6092. http://dx.doi.org/10.1364/OPEX.12.006088D. Gapont, “Quasi-Single-Mode Fiber Laser Nears 2 kW Output with High-Quality Beam,” Laser Focus World, Vol. 41, No. 6, 2005, pp. 9-11.S. Baek, D. B. S. Soh, Y. Jeong, J. K. Sahu, J. Nilsson and B. Lee, “Acladding-Pumped Fiber Laser with Pump- Reflecting Bragg Grating,” IEEE Photonics Technology Letters, Vol. 16, No. 2, 2004, pp. 407-409. http://dx.doi.org/10.1109/LPT.2003.823135I. Kelson and A. Hardy, “Srongly Pumped Fiber Lasers,” IEEE Journal of Quantum Electronics, Vol. 34, No. 9, 1998, pp. 1570-1577. http://dx.doi.org/10.1109/3.709573L. Shang, “Comparative Study of the Output Characteristics of Ytterbium-Doped Double-Clad Fiber Lasers with Different Pump Schemes,” Optik, Vol. 122, No. 21, 2011, pp. 1899-1902.J. F. Li, “Theoretical Analysis of the Heat Dissipation Mechanism in High Power Photonic Crystal Fiber Laser,” Optik, Vol. 121, No. 13, 2010, pp. 1243-1250. http://dx.doi.org/10.1016/j.ijleo.2009.01.015W. M. Rohsenow, J. P. Hartnett and Y. I. Cho, “Handbook of Hear Transfer,” McGraw-Hill, New York, 1998.B. David, “Therma, Stress, and Thermo-Optic Effects in High Average Power Double-Clad Silica Fiber Lasers,” IEEE Journal of Quantum Electronics, Vol. 37, No. 2, 2001, pp. 207-217.J. F. Li, “Theoretical Analysis and Heat Dissipation of Mid-Infrared Chalcogenide Fiber Raman Laser,” Optics Communications, Vol. 284, No. 5, 2011, pp. 1278-1283. http://dx.doi.org/10.1016/j.optcom.2010.10.062P.-X. Li and C. Zhu, “Theorecal and Experimental Investigation of Thermal Effects in a High Power Yb3+-Doped Double-Clad Fiber Laser,” Optics and Laser Technology, Vol. 40, No. 2, 2008, pp. 360-364. http://dx.doi.org/10.1016/j.optlastec.2007.06.011J. P. Holman, “Heat Transfer,” 8th Edition, McGraw-Hill, New York, 1997.