Using DOMDocument in Zendframework2

Using DOMDocument in Zendframework2

I would like to use DOMDocument in ZendFramework 2 but I don't know how.
My normal script (non-zf2) looks as follows:
<?php
...
$response = $client->$webservice($variables);
$dom = new DOMDocument();
$dom->loadXML($response->$property);
return $dom;
And it works fine. But I want to use this in my ZendFramework 2
Application. But this line:
$dom = new DOMDocument();
gives me this error: Fatal error: Class 'Sols\Model\DOMDocument' not found
in... I thought mayby I should use Zend\Dom\Query but that won't work
either. How to be able to use the "standard" DOMDocument in
ZendFramework2?
By the way, DOMDocument works fine on my server (if I don't use it within
ZendFramework2)...
Thank you very much :-)