This can be done solo, you do not need a second person in the helicopter to shine the spotlight.
Start by putting the difficulty on Regular, this will make this a very easy achievement to obtain.
Ride in the helicopter and kill enemies until all four pieces of Intel have dropped onto the ground. You will then land on the helipad and jump out of the helicopter in order to retrieve the pieces of Intel. While the helicopter is flying around above you, it will shine it's spotlight on enemies, blinding them. Simply run around in the courtyard and stab the enemies while they are blinded by the spotlight. You have to face them toward the spotlight in order to blind them, if they are "locked on" to you before you stab them. (The spotlight can't be shining at their back, it must hit them from the front for them to be blinded.)
ALSO, enemies that are stunned by flash bang grenades count toward this achievement making this even easier.