LTu2H.2.pdf
Frontiers in Optics/Laser Science 2015 © OSA 2015
Multi-Core Fiber Lasers J. Anderson,1 C. Jollivet,1 A. Van Newkirk,1 K. Schuster,2 S. Grimm,2 and A. Schülzgen1 1
CREOL, the College of Optics and Photonics, University of Central Florida, Orlando, FL 32816, USA 2 Leibniz Institute of Photonic Technology e.V., A.-Einstein-Str. 9, 07745 Jena, Germany
[email protected]
Abstract: The operation of multi-core fiber lasers with and without supermode selection will be discussed. Supermode specific gain measurements and roundtrip losses, as well as the dynamic behavior of multi-core fiber lasers will be presented. OCIS codes: (060.3510) Lasers, fiber; (060.4005) Microstructured fibers; 060.2270 Fiber characterization
1. Introduction Advanced fiber fabrication techniques enable the fabrication of precisely controlled micro-structured optical fibers including the creation of passive and active micro-structured multi-core fibers (MCF). MCFs can find potential applications in telecommunications [1,2], fiber laser and amplifier systems [3], and fiber-based sensors [4], to name a few examples. Among MCF designs, two main categories can be distinguished. Isolated core MCF structures ensure low cross-talk between the multiple cores forcing each core to act as a single emitter, a feature often important in telecommunications. On the other hand, interaction between cores in coupled-core MCF (CC-MCF) results in supermode formation. Here, we focus on the integration of active CC-MCF into monolithic fiber lasers operating in single and multi-supermode regimes. 2. Coupled-cores multi-core fiber lasers Most CC-MCF lasers demonstrated to date focus on the exclusive operation in the in-phase supermode combining high brightness and near-diffraction limited far field profile. Several methods were successfully demonstrated to select the in-phase supermode such as phase-locking [5] and Talbot cavities [6]. On the other hand, the potential of multi-supermode lasing in CC-MCF has not been analyzed in detail due significantly higher experimental challenges in achieving well-controlled operation conditions. A few numerical studies have attempted to uncover the physics behind multi-supermode amplification and to predict mode competition behavior [7,8]. One of our most recent experiments demonstrates the potential of multi-supermode lasers. An example of a cladding-pumped monolithic fiber laser using CC-MCF with 7 Yb-doped cores [9] as the gain medium is shown in Fig. 1. The capability of CC-MCF lasers to operate in very interesting regimes is illustrated on the right hand side of Fig. 1. When a long segment (>10 m) of SM980 is inserted (spliced) into the cavity, the laser operates in a modelocking regime, characterized by a repetition rate of about 2 MHz at an average power around 120 mW. This work is supported by ARO through grants W911NF-10-1-0441 and W911NF-12-1-0450. References:
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[1] D. J. Richardson et al., “Space division multiplexing in optical fibres,” Nat. Photonics, 7, 354 (2013). [2] R. G. H. van Uden et al., “Ultra-High-Density Spatial Division Multiplexing with a Few-Mode Multicore Fibre,” Nat. Photonics, 8, 865 (2014). [3] D. J. Richardson et al., “High power fiber lasers: current status and future perspectives,” J. Opt. Soc. Am. B, 27, B63 (2010). [4] J. E. Antonio-Lopez et al., “Multicore fiber sensor for high-temperature applications up to 1000 °C”, Opt. Lett., 39(15), 4309 (2014). [5] L. Li et al., “Phase-locked multicore all-fiber lasers: modeling and experimental investigation”, J. Opt. Soc. Am. B, 24(8), 1721 (2007) [6] L. Michaille et al., “Multicore photonic crystal fiber lasers for high power/energy applications”, Opt. Lett., 30(13), 1668 (2005) [7] Y. Huo et al., “Analysis of transverse mode competition and selection in multicore fiber lasers,” J. Opt. Soc. Am. B, 22(11), 2345 (2005) [8] A. S. Kurkov et al., “Mechanism of mode coupling in multicore fiber lasers,” Opt. Lett., 33,(1), 61 (2008) [9] C. Jollivet et al., "Mode-Resolved Gain Analysis and Lasing in Multi-Supermode Multi-Core Fiber Laser,” Opt. Express 22, 30377 (2014).
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Fig. 1. Left: Monolithic fiber laser using a high reflector fiber Bragg grating (HR FBG) and Fresnel reflection form the cleaved MCF facet to form the laser cavity. The laser is pump through a multiport pump combiner (PC) and contains sections of active Yb-doped 7-core fiber (MCF), double clad fiber (DCF) and SM980 with variable length. Right: Oscilloscope trace of the MCF laser output during mode-locked operation with an average power of 120 mW and a repetition rate of 1.93 MHz.
