The Costa Rica international is impressing in his first season in the Primera Division.
"Arsenal noticed me when I was playing with Costa Rica in the Copa America of 2011. They came and showed interest. I signed with the English club for five seasons. It is one of the best teams in the world, offering me great career potential. It's a great club," Campbell told marca.com.
"For now I just think about the Betis. I could stay at Arsenal, but a problem with the work permit meant I had to go out on loan. Last year I played with the French Lorient and this season I'm in Spain. If I signed for five seasons it is because Arsenal are including me in their future."