Abstract: A quantum cascade laser amplifier (12) having an active zone (20) includes a stack of raw layers of semi-conductor materials formed in an epitaxial manner on a substrate layer (16) of indium. phosphide (InP) or gallium arsenide (GaAs) bearing the active zone (20), and a vertical anti-reflection coating (34) that covers an outlet face (28) of the laser radiation made of materials having given refraction indices and a predetermined thickness so that the entire laser radiation can flow through the outlet face. The anti-reflection coating (34) includes a first layer (36) having a first predetermined retraction index (n1) lower than the predetermined refraction index (nD), and at least a second layer (38) having a second refraction index (n2) higher than the predetermined refraction index (nD), wherein the first layer (36) of the anti-reflection coating (34) is made of yttrium fluoride (YF3).

Abstract: A quantic cascade laser amplifier (12) having an active zone (20) includes a stack of raw layers of semi-conductor materials formed in an epitaxial manner on a substrate layer (16) of indium phosphide (InP) or gallium arsenide (GaAs) bearing the active zone (20), and a vertical anti-reflection coating (34) that covers an outlet face (28) of the laser radiation made of materials having given refraction indices and a predetermined thickness so that the entire laser radiation can flow through the outlet face. The anti-reflection coating (34) includes a first layer (36) having a first predetermined refraction index (n1) lower than the predetermined refraction index (nD), and at least a second layer (38) having a second refraction index (n2) higher than the predetermined refraction index (nD), characterised in that the first layer (36) of the anti-reflection coating (34) is made of yttrium fluoride (YF3).