Fig. 3: Superradiance emission for the SL probed in two opposite directions as a function of the frequency detuning of the probe light.

a, b The results for SLs with only the on-resonant standing-wave coupling fields. (a1)–(a5) and (b1)–(b5) are experimental data and numerical simulations with both standing-wave coupling fields for different phases θ = −π∕2, −π∕4, 0, π∕4, π∕2, respectively. The red and blue colors are for the results in two opposite probe directions. The powers of the near-resonant and far-detuned coupling fields are 200 μW and 100 μW, respectively. In the numerical simulation, coupling strengths Ω_r = 2π × 15 MHz, κ = 2π × 2.25 MHz, detuning Δ_c = 2κ, and phase mismatch δk = 0.01k_p.