@article {8503,
	title = {Folded free-space polarization-controlled multistage interconnection network},
	journal = {Applied Optics},
	volume = {37},
	number = {29},
	year = {1998},
	pages = {6884-6891},
	abstract = {We present a folded free-space polarization-controlled optical multistage interconnection network (MIN) based on a dilated bypass{\textendash}exchange switch (DBS) design that uses compact polarization-selective diffractive optical elements (PDOE{\textquoteright}s). The folded MIN design has several advantages over that of the traditional transparent MIN, including compactness, spatial filtering of unwanted higher-order diffraction terms leading to an improved signal-to-noise ratio (SNR), and ease of alignment. We experimentally characterize a folded 2 {\texttimes} 2 switch, as well as a 4 {\texttimes} 4 and an 8 {\texttimes} 8 folded MIN that we have designed and fabricated. We fabricated an array of off-axis Fresnel lenslet PDOE{\textquoteright}s with a 30:1 SNR and used it to construct a 2 {\texttimes} 2 DBS with a measured SNR of 60:1. Using this PDOE array in a 4 {\texttimes} 4 MIN resulted in an increased SNR of 120:1, highlighting the filtering effect of the folded design.},
	url = {https://www.osapublishing.org/ao/abstract.cfm?uri=ao-37-29-6884},
	author = {Dan M. Marom and Paul E. Shames and Fang Xu and Yeshaiahu Fainman}
}
