FROG is currently the most commonly used technique for measuring ultrashort laser pulses. But that doesn't mean we've stopped working on it.
While FROG is not complex, we can simplify it greatly. We can replace the beam splitter, delay line, and beam-recombining optics with a single optic, called a Fresnel biprism. And we can replace the usual thin nonlinear medium and spectrometer with a thick nonlinear crystal.
Invented in 1999 by Rick Trebino, GRENOUILLE, like FROG, is simple, reliable, and accurate. It never misaligns and is very easy to use. Indeed, Pam Bowlan and Rick Trebino have even recently extended its range to nanosecond pulses!