Hooker Jimmy Stevens, prop Jonny Harris and wing Alex Lewington have all been on dual registrations with Nottingham this season, helping them to reach the Championship play-offs.
"I have been impressed with what these players have already achieved at Leicester and Nottingham," Irish rugby director Brian Smith said.
"I am sure we can develop them further, and I expect all three will be pushing for a place in our matchday squad. If they put their heads down, I have no doubt they can go on to higher honours."
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