You've stumbled here on a proper English idiom which may (for all I know) be unusual or unique to English, which occurs a lot, and to use which marks one out as fluent.
It's a way of predicating a quality or attribute of a thing or person, using the preposition "of". As always, the paradigm is in the Authorized Version of the Bible: "He is ... a man of sorrows... " (Isaiah 53.3). The form is "N is a [noun1] of [noun2]" - where noun2 is a quality or attribute which noun1 possesses.
(So right here you have two distinctive features of English: lots of work done by idiomatic use of prepositions; word order critical to sense.)
The attribute is very often a noun phrase - "a woman of a certain age" / "a horse of a different colour". And that's what you're dealing with here. The sentence in question is a bit clunky, because "picosecond" is being used as an adjective but doesn't have the form of an adjective.
It's also ambiguous, because if you gloss "picosecond" as "picosecond-long" it means the pulse can be one picosecond; if you gloss it as "measured-in-picoseconds" then it could be anything from 0.1 (below which you'd probably talk in femtoseconds) to at least 99 (after which you might start talking tenths of a nano-second).
So, not a nice sentence, but a way into a wonderful linguistic world.