Upper bounds on the computational power of an optical model of computation

We present upper bounds on the computational power of an optical model of computation called the C2-CSM. We show that C2-CSM time is no more powerful than sequential space, thus giving one of the two inclusions that are necessary to show that the model verifies the parallel computation thesis. Furthermore we show that C2-CSMs that simultaneously use polynomial space and polylogarithmic time decide no more than the class NC