We report a novel CW tunable high-power single-longitudinal-mode fiber laser with a linewidth of 9？MHz. A tunable fiber Bragg grating provided wavelength selection over a 10？nm range. An all-fiber Fabry-Perot filter was used to increase the longitudinal mode spacing of the laser cavity. An unpumped polarization-maintaining erbium-doped fiber was used inside the cavity to eliminate mode hopping and increase stability. A maximum output power of 300？mW was produced while maintaining single-longitudinal-mode operation. 1. Introduction Fiber lasers are established as robust and reliable devices with a variety of applications in industry and medicine due to their unique characteristics, such as all-fiber designs, compact size, cost-effective production and operation, and the no need for realignment or external cooling. High-power single-wavelength and multiwavelength infrared fiber lasers are very attractive for applications in optical communications, sensing, spectroscopy, biomedical instrumentation, and nonlinear optics. The continued progress in fiber pumping techniques, advanced fiber designs, and fabrication processes, as well as the availability of high-power pump diodes, has assisted in the development of high-power fiber lasers [1–5]. Fiber lasers have found applications in temperature and strain sensors [6–11], medical diagnostics [12–14], and industrial processing [15]. High-power fiber lasers using erbium-ytterbium codoped fibers as the gain medium, which operates in the eye-safe (1.5？μm to 1.6？μm) spectral range, can now compete with traditional solid-state bulk lasers. The applications of recently reported single-wavelength [16, 17] and multiwavelength [18, 19] high-power fiber lasers were limited due to large linewidth of the lasing wavelength, multi-longitudinal-mode oscillations, small tuning range, and complex designs. In this paper we present a novel tunable, high-power, single-wavelength, single-longitudinal-mode, fiber ring laser. 2. Experimental Setup The experimental setup of the fiber laser is shown in Figure 1. The resonant cavity consists of a high-power polarization-independent optical isolator (OI), which guaranteed the unidirectional propagation and thus eliminated the spatial hole-burning effects [20]; an all-fiber polarization controller; a commercially available tunable fiber Bragg grating (TFBG) with a tuning range of 10？nm (1565？nm–1575？nm); a 4？m long double-clad erbium-ytterbium codoped (DC-EYDF) fiber with core/cladding diameters of 10/131？μm which was used as the gain medium. In general to produce high output power from a
References
[1]
J. Nilsson, J. K. Sahu, Y. Jeong et al., “High power fiber lasers: new developments,” in Proceedings of the SPIE: Advances in Fiber Devices, vol. 4974, pp. 50–59, January 2003.
[2]
J. K. Sahu, Y. Jeong, C. Codemard et al., “Tunable narrow linewidth high power erbium: ytterbium co-doped fiber laser,” in Proceedings of the Conference on Lasers and Electro-Optics (CLEO '04), vol. 1, pp. 159–160, May 2004.
[3]
M. Laroche, P. Jander, W. A. Clarkson, J. K. Sahu, J. Nilsson, and Y. Jeong, “High power cladding-pumped tunable Er, Yb-doped fibre laser,” Electronics Letters, vol. 40, no. 14, pp. 855–856, 2004.
[4]
Y. Jeong, J. K. Sahu, D. N. Payne, and J. Nilsson, “ytterbium-doped large-core fiber laser with 1.36 kW continuous-wave output power,” Optics Express, vol. 12, no. 25, pp. 6088–6092, 2004.
[5]
Y. Jeong, J. Nilsson, J. K. Sahu et al., “Single-mode plane-polarized ytterbium-doped large-core fiber laser with 633-W continuous-wave output power,” Optics Letters, vol. 30, no. 9, pp. 955–957, 2005.
[6]
Q. Wang, L. Zhang, C. Sun, and Q. Yu, “Multiplexed fiber-optic pressure and temperature sensor system for down-hole measurement,” IEEE Sensors Journal, vol. 8, no. 11-12, Article ID 4666724, pp. 1879–1883, 2008.
[7]
S. Watson, M. J. Gander, W. N. MacPherson et al., “Laser-machined fibers as Fabry-Perot pressure sensors,” Applied Optics, vol. 45, no. 22, pp. 5590–5596, 2006.
[8]
S. Trpkovski, S. A. Wade, S. F. Collins, and G. W. Baxter, “Er3+: Yb3+ doped fibre with embedded FBG for simultaneous measurement of temperature and longitudinal strain,” Measurement Science and Technology, vol. 16, no. 2, pp. 488–496, 2005.
[9]
J. Mandal, S. Pal, T. Sun, K. T. V. Grattan, A. T. Augousti, and S. A. Wade, “Bragg grating-based fiber-optic laser probe for temperature sensing,” IEEE Photonics Technology Letters, vol. 16, no. 1, pp. 218–220, 2004.
[10]
H. H. Kee, G. P. Lees, and T. P. Newson, “All-fiber system for simultaneous interrogation of distributed strain and temperature sensing by spontaneous Brillouin scattering,” Optics Letters, vol. 25, no. 10, pp. 695–697, 2000.
[11]
M. Niklès, L. Thévenaz, and P. A. Robert, “Simple distributed fiber sensor based on Brillouin gain spectrum analysis,” Optics Letters, vol. 21, no. 10, pp. 758–760, 1996.
[12]
P. M. Talaia, A. Ramos, I. Abe et al., “Plated and intact femur strains in fracture fixation using fiber Bragg gratings and strain gauges,” Experimental Mechanics, vol. 47, no. 3, pp. 355–363, 2007.
[13]
E. J. Seibel, R. E. Carroll, J. A. Dominitz et al., “Tethered capsule endoscopy, a low-cost and high-performance alternative technology for the screening of esophageal cancer and Barrett's esophagus,” IEEE Transactions on Biomedical Engineering, vol. 55, no. 3, pp. 1032–1042, 2008.
[14]
Y. Sasaki, S. Tanosaki, J. Suzuki et al., “Fundamental imaging properties of transillumination laser CT using optical fiber applicable to bio-medical sensing,” IEEE Sensors Journal, vol. 3, no. 5, pp. 658–667, 2003.
[15]
L. Quintino, A. Costa, R. Miranda, D. Yapp, V. Kumar, and C. J. Kong, “Welding with high power fiber lasers—a preliminary study,” Materials and Design, vol. 28, no. 4, pp. 1231–1237, 2007.
[16]
A. Polynkin, P. Polynkin, M. Mansuripur, and N. Peyghambarian, “Single-frequency fiber ring laser with 1 W output power at 1.5 μm,” Optics Express, vol. 13, no. 8, pp. 3179–3184, 2005.
[17]
Y. Jeong, C. Alegria, J. K. Sahu et al., “A 43-W C-band tunable narrow-linewidth erbium-ytterbium codoped large-core fiber laser,” IEEE Photonics Technology Letters, vol. 16, no. 3, pp. 756–758, 2004.
[18]
Z. G. Lu, F. G. Sun, G. Z. Xiao, P. Lin, and P. Zhao, “High-power multiwavelength Er3+-Yb3+ codoped double-cladding fiber ring laser,” IEEE Photonics Technology Letters, vol. 17, no. 9, pp. 1821–1823, 2005.
[19]
X. X. Yang, L. Zhan, Q. S. Shen, and Y. X. Xia, “High-power single-longitudinal-mode fiber laser with a ring Fabry-Pérot resonator and a saturable absorber,” IEEE Photonics Technology Letters, vol. 20, no. 11, pp. 879–881, 2008.
[20]
P. W. Milonni and J. H. Eberly, Laser Physics, John Wiley & Sons, New York, NY, USA, 2010.
[21]
D. Kouznetsov and J. V. Moloney, “Efficiency of pump absorption in double-clad fiber amplifiers. II. Broken circular symmetry,” Journal of the Optical Society of America B, vol. 19, no. 6, pp. 1259–1263, 2002.
[22]
G. Das and Z. J. Chaboyer, “Single-wavelength fiber laser with 250 mW output power at 1.57 μm,” Optics Express, vol. 17, no. 10, pp. 7750–7755, 2009.
[23]
P. Urquhart, “Compound optical-fiber-based resonators,” Journal of the Optical Society of America A, vol. 5, no. 6, pp. 803–812, 1988.
[24]
S. J. Hogeveen and H. Vandestadt, “Fabry-Perot interferometers with 3 mirrors,” Applied Optics, vol. 25, no. 22, pp. 4181–4184, 1986.
[25]
H. Vandestadt and J. M. Muller, “Multimirror Fabry-Perot interferometers,” Journal of the Optical Society of America A, vol. 2, no. 8, pp. 1363–1370, 1985.
[26]
Y. Cheng, J. T. Kringlebotn, W. H. Loh, R. I. Laming, and D. N. Payne, “Stable single-frequency traveling-wave fiber loop laser with integral saturable-absorber-based tracking narrow-band-filter,” Optics Letters, vol. 20, no. 8, pp. 875–877, 1995.
[27]
A. L. Schawlow and C. H. Townes, “Infrared and optical masers,” Physical Review, vol. 112, no. 6, pp. 1940–1949, 1958.
[28]
N. Y. Voo, P. Horak, M. Ibsen, and W. H. Loh, “Anomalous linewidth behavior in short-cavity single-frequency fiber lasers,” IEEE Photonics Technology Letters, vol. 17, no. 3, pp. 546–548, 2005.
[29]
P. Horak, N. Y. Voo, M. Ibsen, and W. H. Loh, “Pump-noise-induced linewidth contributions in distributed feedback fiber lasers,” IEEE Photonics Technology Letters, vol. 18, no. 9, pp. 998–1000, 2006.
[30]
M. A. Lapointe and M. Piché, “Linewidth of high-power fiber lasers,” in Proceedings of the SPIE: Photonics North, vol. 7386, pp. 73860S-1–73860S-8, 2009.
[31]
V. Roy, M. Piché, F. Babin, and G. W. Schinn, “Nonlinear wave mixing in a multilongitudinal-mode erbium-doped fiber laser,” Optics Express, vol. 13, no. 18, pp. 6791–6797, 2005.
