Novel single-mode fiber coupled broadband seed source for pulsed fiber laser systems

Single-transverse-mode semiconductor laser diodes with broad emission spectrum in pulsed or CW regime are attractive as seed sources in fiber laser systems. Stimulated Brillouin scattering can be a limiting factor in such systems, causing damaging high power pulses to reverse propagate in the fibre. The effect can be significantly mitigated by broadening the linewidth of the seed laser. Here we report on such a seed source capable of operating in either CW or pulsed mode with a center wavelength at around 1060 nm and spectral full width at half maximum of greater than 10 nm. The new source is based on well-established ridge waveguide pump laser technology, modified for operation in a superluminescent regime. A coupling efficiency of ~80 % into a single mode fiber is achieved. Our time resolved spectral studies show that the device is demonstrating fast modulation rate and very high peak optical power up to 1 W while maintaining a broad emission spectrum greater than 10 nm.