PHP ORM for Ember-Data [EmberJS]

I am looking for any PHP ORM library that pairs well with any Ember-Data serializer.

I want to write backend for my EmberJS app in PHP Slim-Framework, and I need model library which has backend or client adapter for Ember-Data.

I tried Eloquent ORM, but it's toJSON() functionallity isn't any close to any Ember-Data serializer.

Marcin