Abstract: An opto-isolator is provided that is designed for optically interconnecting devices that are mounted on multiple PCBs. The opto-isolator is particularly well suited for arrangements where the PCB-to-PCB distance is very small. In such cases, using an optical fiber as the optical waveguide can result in the optical fiber being bent beyond its minimum bend radius, resulting in damage to the optical fiber and/or performance problems due to attenuation of the optical signal. The opto-isolator includes first and second generally rigid structures that engage one another with an alignment tolerance that ensures proper board-to-board alignment while also facilitating the ease with which the alignment process can be performed. Once the first and second generally rigid structures are in engagement with one another, they form a generally rigid optical waveguide structure for coupling light from an optical transmitter of one of the PCBs onto an optical receiver of the other PCB.