PHP: จะรวมข้อมูล Array 2 ตัวเข้ารวมกันด้วย PHP ต้องทำยังไง

<?php
$array1 = array("A","B","C","D");
$array2 = array("A","B","C","D");

$new_array = array();

foreach($array1 as $a1){
	foreach($array2 as $a2){
		$val = $a1.$a2;
		array_push($new_array,$val);
		echo $val." ";
	}

	echo "<br />";
}
//var_dump($new_array);
?>