Fiber-Optic Waveguide Devices and Sensors

An optical waveguide is a spatially inhomogeneous structure for guiding light, i.e. for restricting the spatial region in which light can propagate. Generally, a waveguide comprises a region of increased refractive index, compared with the surrounding medium.

Applications

• Optical fibers allow the transmission of light over long distances, e.g. for optical fiber communications.
• On photonic integrated circuits, as used e.g. in silicon photonics, waveguides guide light between different optical components.
• In the future, silicon waveguides on digital processor chips and polymer waveguides in circuit boards may be used for fast optical data transmission between components of computers.
• Some waveguides are used for maintaining high optical intensities over appreciable lengths, e.g. in nonlinear devices like frequency doublers and Raman lasers. Active (amplifying) waveguides are used in waveguide lasers and amplifiers. Important examples are fiber lasers and fiber amplifiers.
• A waveguide can be used for stripping off higher-order transverse modes, thus acting as a mode cleaner.
• In some cases, an interaction of the guided light with the material in the evanescent field is used, e.g. in certain waveguide sensors.
• Waveguides can also be employed for splitting and combining light beams, e.g. in integrated optical interferometers.