But here is the dirty secret of experimentalists:
Now go build your laser table. And keep a copy of Mukamel on the shelf for when your advisor visits. You can open it to a random page and say, “Yes, I was just checking the fourth-order response.” They will never know. But here is the dirty secret of experimentalists:
In linear spectroscopy (absorption), you poke once, the polarization wiggles, and you measure the wiggle decay. Boring. you poke once
If your signal is weak, use a boxcar geometry (beams at three corners of a square). The signal goes out the fourth corner. No fancy optics required. the polarization wiggles