Four-mode multiplexing and manipulation technologies are reviewed in the context of space-division multiplexing (SDM) optical communication systems. These are multiplane light conversion (MPLC), fused fiber devices, such as photonic lanterns and tapered fiber bundles, 3-D waveguides fabricated using ultrafast laser inscription, and free-space imaging systems. Each device has its unique strengths and use cases. MPLC can create very complex transformations between two arbitrary sets of spatial modes and leverages mature gray-scale lithographic techniques. Photonic lanterns and tapered fiber bundles are all-fiber devices that can convert beams on single-mode fiber inputs into spatial modes. The all-fiber construction leads to very low losses and high-power handling. 3-D waveguides are inscribed into a glass block using ultrashort lasers and can arbitrarily route light in 3-D. Finally, free-space systems using lenses can also relay many multicore and multimode beams through a single free-space device, such as a thin film filter or an optical isolator. These four technologies have enabled hero transmission experiments in the multimode, multicore, and multimode fiber.

The Massachusetts Institute of Technology's iLab project has developed a distributed software toolkit and middleware service infrastructure to support Internet-accessible laboratories and promote their sharing among schools and universities on a worldwide scale. The project starts with the assumption that the faculty teaching with online labs and the faculty or academic departments that provide those labs are acting in two roles with different goals and concerns. The iLab architecture focuses on fast platform-independent lab development, scalable access for students, and efficient management for lab providers while preserving the autonomy of the faculty actually teaching the students. Over the past two years, the iLab architecture has been adopted by an increasing number of partner universities in Europe, Australia, Africa, Asia, and the United States. The iLab project has demonstrated that online laboratory use can scale to thousands of students dispersed on several continents.