Kramers–Kronig relation in a Doppler-broadened Λ-type three-level system*
Wang Menga),b), Lu Xiao-Ganga), Bai Jin-Haia), Pei Li-Yac), Miao Xing-Xua), Gao Yan-Leia),b), Wu Ling-Ana), Fu Pan-Minga), Yang Shi-Pingb), Pang Zhao-Guangb), Wang Ru-Quana), Zuo Zhan-Chuna)
       
The dressed energies Δ ± = Γ 10 as a function of coupling coefficient | G 2| = Γ 10 with Γ 20 = Γ 10 = 0.1, and Δ 2 = Γ 10 = 0 (black solid curve), 1 (red dashed curve), 2 (blue dotted curve), and 5 (purple dashed-dotted curve). The upper curves are Im( Δ − = Γ 10), the lower ones are Im( Δ + = Γ 10), and the middle black solid line corresponds to Im( Δ +) = Im( Δ −).