Amplification factor with the best-fit lensing parameters for the three modes with two images shown in Figure A1. The reference likelihood value is the unlensed case. The wave-optics contribution (i.e., full result minus the geometric-optics contribution) is represented with a lighter shade. In all three cases, the diffractive feature at t ∼ 20 ms (left) is very important (note that the feature is defined in lensing time delay, not detector time). The interference between the diffractive feature and the main image produces the main oscillatory pattern observed in F(f) (right), while the secondary image introduces additional wiggles.