Source: https://www.osapublishing.org/oe/abstract.cfm?uri=oe-10-21-1167
Timestamp: 2019-04-23 16:06:36+00:00

Document:
Coherent addition of fiber lasers coupled with an intracavity fiber coupler is reported. Almost a single output is obtained from one of the fiber ports, which one can switch simply by unbalancing the losses in the ports. We show that the constructive supermodes, each of which has a single output in a different port, build up automatically because of the dense longitudinal-mode, length-unbalanced laser array with unbalanced port loss. High addition efficiencies of 93.6% for two fiber lasers and 95.6% for four fiber lasers have been obtained.
D. Botez and D. R. Scifres eds., Diode Laser Arrays (Cambridge University Press, 1994).
M. Wrage, P. Glas, and M. Leitner, “Combined phase-locking and beam shaping of a multicore fiber laser by structured mirrors,” Opt. Lett. 26, 980–982 (2001).
P. K. Cheo, A. Liu, and G. G. King, “A high-brightness laser beam from a phase-locked multicore Yb-doped fiber laser array,” IEEE Photon. Tech. Lett. 13, 439–441 (2001).
V. A. Kozlov, J. Hernández-Cordero, and T. F. Morse, “All-fiber coherent beam combining of fiber lasers,” Opt. Lett. 24, 1814–1816 (1999).
E. M. Dianov, M. V. Grekov, I. A. Bufetov, S. A. Vasiliev, O. I. Medvedkov, V. G. Plotnichenko, V. V. Koltashev, A. V. Belov, M. M. Bubnov, S. L. Semjonov, and A. M. Prokhorov, “CW high power 1.24μm and 1.48μm Raman lasers based on low loss phosphosilicate fibre,” Electron. Lett. 33, 1542–1544 (1997).
N. S. Kim, M. Prabhu, C. Li, J. Song, and K. Ueda, “Output characteristics of P-doped Raman fiber laser at 1484 nm with 2.11 W maximum output power pumped by CW 1064 nm Yb-doped double-clad fiber laser,” Jpn. J. Appl. Phys. 39, 6264–6267 (2000).
D. Mehuys, K. Mitsunaga, L. Eng, W. K. Marshall, and A. Yariv, “Supermode control in diffraction-coupled semiconductor laser arrays,” Appl. Phys. Lett. 53, 1165–1167(1988).
N. M. Lyndin, V. A. Sychugov, A. E. Tikhomirov, and A. A. Abramov, “Laser system composed of several active elements connected by single-mode couplers,” Quantum Electron. 24, 1058–1061 (1994).
P. W. Smith, “Stabilized, single-frequency output from a long laser cavity,” IEEE J. Quantum Electron. QE-1, 343–348 (1965).
P. Barnsley, P. Urquhart, C. Millar, and M. Brierley, “Fiber Fox-Smith resonators: application to single-longitudinal-mode operation of fiber lasers,” J. Opt. Soc. Am. A 5, 1339–1346 (1988).
Fig. 1. Experimental setup of the fiber laser array. The dashed lines indicate the independent array without a 50:50 fused-fiber coupler. PC, polarization controller; EDF, Er-doped fiber.
Fig. 2. Dependence of the output powers on the pump power launched on each WDM coupler. P A (red) and P B (blue) of the initial independent array (open circles) and those of the coupled array (filled circles) are shown. Inset: spectra of the port A (red) and port B (blue) outputs for the independent array (dashed curves) and the coupled array (solid curves) at maximum pumping.
Fig. 3. Change with tuning λBraggA. (a) Spectra of port A (red curves) and port B (blue curves) outputs. The positions of λBraggA and λBraggB are indicated by red and blue dashed lines, respectively. (b) P A (red filled circles), P B (blue filled circles), and P A+P B (filled squares).
Fig. 4. Dependence of P A (red filled circles), P B (blue filled circles), and P A+P B (filled squares) on the additional loss applied to port A.
Fig. 5. (a) Beat spectra of the port A output (red curves) and port B output (blue curves) when the Y A mode was excited at ΔL = 0.341 m. Fine structures of the port B output are smeared out because of limited resolution. (b) Beat spectra with higher resolution.
Fig. 6. Line-shape functions g 1(v) (red curve) and g 2(v) (blue curve) at the lowest frequency region in the Fox–Smith limit. Characters YA indicate the positions of the YA modes estimated from the beat spectrum in Fig. 5.
Fig. 7. Experimental setup of the N = 4 fiber laser array. PC, polarization controller; EDF, Er-doped fiber.

References: V. 
 V. 
 V. 
 V. 
 V. 
 V.