$string = "s005219/Doe John|John.Doe\\";
$string = ~/s\d+\/([^|]*)/;
print $1
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Assumptions:

1. each string starts with an 's' then a number
2. the number is a decimal integer
3. There will be no | character in the name

It can be simpler than this and remove the limits of assumption 1 and 2, excercise left for the OP.

Cheers,
R.