Complex widget options

Let’s say I wanted to make a widget with a set of images. I’ve worked out how to store an array in my widget options:
<input class="image-id-value" type="hidden" name="<?php echo $this->get_field_name( 'attachment_ids' ) ?>[<?php echo $key ?>]" value="<?php echo $image_id; ?>">

And to store that via my update options.

But what if I wanted each image to be an array:

$image['id']
$image['caption']
$image['link']

Or an object:

$image->id
$image->caption
$image->link

Is there a straightforward way to set up the data that I place in the input value so that i can store it nicely in ‘update_options’?

Can anyone suggest some example plugins that accomplish this that I could look at?