Spectral Beam Combination (SBC) of a Laser Diode (LD) with Fiber Output.

The external cavity spectral beam combining (SBC) of a laser diode (LD) with fibre output was researched. We proposed a method to achieve dense wavelength beam combination based on a LD with fibre output. In order to demonstrate our conception, two LDs with pigtail output, centre wavelength of 976 nm, and about 45% of electric-to-optical (E-O) conversion efficiency was employed to achieve spectral beam combination. This method demonstrated the feasibility of closed loop SBC of LD with pigtail. The free running spectrum, single laser spectrum with locked wavelength, spectrum after combination were measured. The feedback efficiency of external cavity was about 1.55% when the transmission of cavity output mirror was about 30%. The combination power of 1.63 W was obtained, the optical-to-optical (O-to-O) transferable efficiency was about 25%. The deterioration factor beam quality was about 1.2×, meanwhile, the efficiency loss of SBC and the reason of deterioration of beam quality were analysed. According to the results, we designed the kilowatt level LD with fibre output, the O-O efficiency can be increased to about 70%. [ABSTRACT FROM AUTHOR]