You would have really enjoyed an old timer that used to post here, PhotonicsGuy. CTO of a defense contracting company who designs PICs. Has more experience with discrete devices but his engineering knowledge was a fantastic resource here.
I didn’t see Vpp referenced in the paper and generally the best “yardstick” to compare modulators is Vpi or VpiL so that’s what I like to reference. I’m sure you already know that lol. I have no engineering background. Just spend too much time studying this.