Assessment of integration of off-axis Fresnel lenses into a free-space interconnect.
The integration of multiple optical functions into a single optical element is often seen as advantageous to improve practicality and/or performance. In free-space devices, a common way to achieve this is to use off-axis Fresnel lenses to simultaneously collimate and redirect light. We study the impact of this type of integration on assembly tolerances and performance of a free-space interconnect designed to format a one-dimensional set of inputs into a two-dimensional array. Two systems are built and compared: one where light collimation and redirection are performed by different elements and one where these functions were combined into off-axis Fresnel lenses. The integrated system has lower losses but exhibits higher polarization sensitivity.