The sine angle is in radians and ω is the frequency in radians. The Φ stands for a phase shift. So you can think of A as the amplitude — if A is, say, 5 then the output will go from -5 to 5.

The phase shift grows linearly for low photon numbers and a fit yields a slope of 13 ± 1 μrad per photon. There is a saturation at high photon numbers that occurs when the induced a.c.-Stark ...