Higher-order Modes

A mode is the spatial distribution of light inside an optical fiber. Traditionally, fibers have been engineered to be single-moded, since this is generally advantageous in optical communications. Despite of this, there has lately been much interest in applications uniquely enabled by Higher-order modes (HOMs).  

HOMs can be engineered to have special dispersion properties, making them ideal for certain tasks.  Examples of such are nonlinear frequency conversion at wavelengths not feasible with traditional single-mode fibers, or dispersion compensation in femtosecond fiber lasers.

Another area of application is communication. Each fiber mode can be used as an individual communication channel to increase bandwidth. This kind of parallelism is commonly known as mode division multiplexing.

In some applications, such as high-power fiber lasers, single-moded operation is advantageous. However, it is not possible to make the fiber strictly single-moded. Therefore, it is important to be able to identify HOMs, thus making it possible to avoid them.

Our activities in HOM

  • Generation of HOMs, in both fibers and free space
  • Characterization of HOMs
  • Simulations of nonlinear effects in HOMs

International partners

  • Sidharth Ramachandran, Boston University

Commercial partners

  • NKT photonics
  • OFS fitel