How to add custome class in laravel 5.4.10

I am new in laravel. I am writing following code in the controller method.

include_once(app_path() .'/Classes/Pgp_2fa.php');
$pgp = new Pgp_2fa();

Following errors are shown.

FatalThrowableError in AuthController.php line 146: Class 'App\Http\Controllers\Pgp_2fa' not found

via Chebli Mohamed