(color online) Typical 6S_1/2 (F = 4) → 6P_3/2 (F′) → nD EIT spectra of the hyperfine splitting of intermediate states and fine structure splitting of Rydberg states. Because of the Rydberg splitting, the D_3/2 and D_5/2 states scale with Δ_c = (1 − λ_p/λ_c)Δ_p. The peaks labeled 1–3 respectively represent F = 4 → F′ = (3,4,5) → nD_5/2, and the peaks labeled 4–6 respectively represent F = 4 → F′ = (3,4,5) → nD_3/2. The horizontal coordinate is calibrated using the modulation sidebands of the λ = 509 nm laser. The green dashed line shows the peak overlap of the 6S_1/2 (F = 4) → 6P_3/2 (F′ = 5) → 59D_5/2 and 6S_1/2 (F = 4) → 6P_3/2 (F′ = 3) → 59D_3/2. The Rabi frequencies of probe laser and coupling laser are ∼ 1 MHz and ∼ 1 MHz, respectively.