[javascript] Adding value to input field with jQuery

I want to add some value in an input field with jQuery. The problem is with the ID of the input field. I am using the id such as options[input2]. In that case my code does not work. If I use ID like input2, then it works fine. I need to use options[input2], how can I fix the code?

HTML:

<div>
    <h3>Working</h3>
    <input id="input1" type="text" value="" />
    <input class="button" type="button" value="Add value" />
</div>

<div>
    <h3>Not working</h3>
    <input id="options[input2]" type="text" value="" />
    <input class="button" type="button" value="Add value" />
</div>

jQuery:

$('.button').click(function(){
    var fieldID = $(this).prev().attr("id");
    $('#' + fieldID).val("hello world");
});

Demo:

http://jsfiddle.net/4XR8M/