Passive coherent beam combining of quantum-cascade lasers with a Dammann grating

Guillaume Bloom (1) , Christian Larat (1) , Eric Lallier (1) , Gaëlle Lehoucq (1) , S. Bansropun (1) , M.-S. L. Lee-Bouhours (1) , Brigitte Loiseaux (1) , Mathieu Carras (2) , Xavier Marcadet (1) , Gaëlle Lucas-Leclin (3) , Patrick Georges (3)

1 Thales Research and Technology [Palaiseau]
2 III-V Lab - Alcatel-Thalès III-V lab
3 Laboratoire Charles Fabry de l'Institut d'Optique / Lasers

An external cavity using a binary phase grating has been developed to achieve coherent combining of five quantum-cascade lasers emitting at 4.65 μm. The grating phase profile is designed to combine five beams of equal intensities into a single beam with a good efficiency (~75%). The performances of this cavity concerning output power, stability, combining efficiency and beam quality are detailed. We report a CW combining efficiency of 66% corresponding to an output power of ~ 0.5 W with a good beam quality (M² < 1.6)

Domains: Optics [physics.optics]

Guillaume Bloom, Christian Larat, Eric Lallier, Gaëlle Lehoucq, S. Bansropun, et al.. Passive coherent beam combining of quantum-cascade lasers with a Dammann grating. Optics Letters, 2011, 36 (19), pp.3810-3812. ⟨hal-00625622⟩