The 20-year-old former Charlton player has featured in Arsenal's three Premier League matches so far this season, in which they are yet to concede a single goal.
"I think it's only natural that the longer you're at a club, the more at home you feel," he told the club's official website.
"Coming here last year I felt a bit blown away with everything. This year I've come back and felt like one of the boys.
"It was different this year and it was nice because you like to feel comfortable and part of things. I'm happy with things at the moment and hopefully we just move on from here.
"My ambition for my whole career is to play for this football club. I want to be good enough and make my mark here. I won't be happy until I'm playing week-in, week-out. That's what I want to achieve."