Yes, you're on the right track with 1.Bb2 but can you work out what follows?
If you think about the moves Black's king can make first of all, then 1...Kg7 is clearly bad because of 2.Rg3+ & the bishop captures the rook but what about 1...Kg8 or 1...Kh7 ?
Then there are all the possible Black rook moves. But the only ones that should give you trouble are 1...Rf7 & 1...Rf8, particularly the latter ! (because the position is symmetrical about the a1-h8 diagonal, solutions are the same as for 1...Rg6 & ..Rh6).
It's really the solution to 1...Rf8 (or ..Rh6) that raises this from being a fairly straightforward & easy puzzle to something a little more special.
I recently came across this puzzle on another site & it had me thinking about it for some time. It's not particularly difficult but there is one variation that needs quite a lot of thought.
Although the objective wasn't stated as such, it's pretty clear that you need to find a way of forcing the exchange of White's bishop for Black's rook....
Hint: >>This uses the principle of Zugzwang !<< (Highlight the text to read the hint)
I'll post the full solution later but I expect some of my fellow 'puzzle junkies' will find it before then. Good luck.
For those who want to see it, click here for the source site.