Visual alignment using image fiber micro-optics for long-distance, ultra-high throughput Space-CDMA based 2-D parallel optical data link

We experimentally demonstrate 100-m-long image fiber transmission of four-channel multiplexed two-dimensional signals. To upgrade the system throughput, we study several hundred Gb/s-class 2-D optical parallel data link using an image fiber for the transmission and 2-D arrays of vertical-cavity surface-emmitting laser diodes (VCSELs) and p-i-n photo-diodes (PDs) as the transmitter and the receiver respectively. This system employs space code division multiple access (Space-CDMA) to multiplex 2-D optical parallel signals. To establish multi-channel optical link between 2-D VCSEL array and PD array with a high alignment precision and a good repeatability, we develop a novel visual alignment technique using a micro-optic image fiber coupler, which consists of miniature cube beamsplitter and graded index (GRIN) rod lenses. The effectiveness of the visual alignment with the image fiber coupler is experimentally demonstrated. This result will encourage the application of optical space-CDMA using an image fiber and 2-D arrays of VCSELs and PDs to future high-throughput 2-D parallel data links connecting massively parallel processors.