Multi-wavelength Brillouin–Erbium fibre laser in a linear cavity M.H. Al-Mansoori, B. Bouzid, B.M. Ali, M.K. Abdullah, M.A. Mahdi * Photonics and Fiber Optic Systems Laboratory, Department of Computer and Communication Systems Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia Received 28 October 2003; received in revised form 13 July 2004; accepted 23 July 2004 Abstract In this paper, we demonstrate a new architecture of multi-wavelength Brillouin/Erbium fibre laser in a linear cavity. The architecture utilised a bi-directional oscillation provided by two fibre loop mirrors at both ends of the laser cavity. The efficiency of bi-directional amplification in the Erbium-doped fibre exhibited a low threshold operation of 5.5 mW pump power of 980 nm to create the first Brillouin Stokes. A stable operation of eighteen Brillouin Stokes with 10.88 GHz spacing was obtained at around 1558 nm band. Ó 2004 Elsevier B.V. All rights reserved. PACS: 42.55.Wd; 42.60.Da; 42.65. k; 42.65.Es; 52.38.Bv Keywords: Fibre lasers; Cavities; Nonlinear Brillouin scattering; Multiwavelength laser source 1. Introduction The key future of optical communication net- works rests in dense wavelength division multi- plexing (DWDM) based systems. This issue has propelled scientists to research on laser sources that would cater and fully utilize the wide band- width that the optical fibre has to offer. Multiple wavelength laser sources have become increasingly important for the applications in DWDM systems. A unique technique of integrating the nonlinear Brillouin gain and the linear Erbium gain in a ring cavity was proposed in [1]. This hybrid technique led to the development of multi-wavelength Bril- louin/Erbium fibre lasers (BEFL) by feeding back the Brillouin Stokes into the cavity via non-reso- nant direction [2]. The number of Brillouin Stokes was increased up to 30 channels by incorporating an internal feedback circuit of Brillouin gain [3]. Bidirectional generation of multi-wavelength Stokes was also investigated using an intra-cavity distributed feedback laser [4] and a twin-cavity [5]. 0030-4018/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.optcom.2004.07.051 * Corresponding author. Tel.: +60 38 9466438; fax: +60 38 6567127. E-mail address: adzir@ieee.org (M.A. Mahdi). Optics Communications 242 (2004) 209–214 www.elsevier.com/locate/optcom