A stable all-fiber dual-wavelength thulium-doped fiber laser (TFL) based on cascaded fiber Bragg grating array is proposed and demonstrated. The TFL operates at 1940.9 and 1948.8 nm simultaneously with a 20 dB optical signal-to-noise ratio (OSNR) ratio. As a proof-of-concept experiment, two dual-wavelength thulium-doped fiber amplifiers are coherently combined. The fringe contrast is improved from nearly 0 to 91% when the system evolves from open-loop to close-loop. The feasibility of application of dual-wavelength TFL in coherent beam combination is verified.
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