using AJAX query to pass javascript array to php

After reading through quite a few posts here, (and even just straight copying code,) I still cannot figure out why this is not working.

On my main page, I have a textbox that a user pastes data into. Upon paste, this script runs (this and the ajax query below are in the same script function):

var lines = $('textarea').val().split('\n');  //create array from pasted data

I now have a JavaScript array with the pasted data. I'm trying to send this over to a separate PHP file that I will load into a div on this main page by doing the following:

$.ajax({
      type: 'POST',
      url: 'return.php',
      data: {lines:lines},        
        success:function(data){
          $("#info").load("return.php");
        }
  });

  for (i=0; i < lines.length; i++) {            // log the output
    if (lines[i]){
    console.log("line ",  i , lines[i]);
    }  
  }

in my return.php file, I have this:

$lines = $_REQUEST['lines'];

echo '<pre>';
echo($lines);
echo '</pre>';

my console.log is outputting the array perfectly, but for some reason it's not making its way over to return.php, as my echo is blank.

What am I doing wrong?