Below is a link to an article in the local paper where a Ohio State Patrolman endorses the use of a headlight modulator to make bikes more visible.
He doesn't specifically use the term modulator but he does describe the effect.
Copied in part here.
"As a motorcycle driver, you need to drive more defensively than you do when you're driving a car," Randall said.
The sergeant said a number of newer features enhance safety.
"There are some headlights that almost look like they're flashing as they come at you," Randall said.
Other enhancements include brighter turn signals and brake lights.
"It's unfortunate that you have to spend the extra money, but in the end it's worth it," Randall said.
http://www.mansfieldnewsjournal.com/article/20120331/NEWS01/203310314/1002/rss01
Gary