Introduction to Optical Waveguides


What are optical waveguides?

Optical waveguides are the key elements of photonic devices that perform guiding, coupling, switching, splitting, multiplexing and demultiplexing of optical signals. Passive waveguides, electrooptic components, transmitters, receivers, and driving electronics can be integrated into one chip using planar technology, similar to microelectronics. Although the operation of waveguide devices is well researched and understood, their particular performance relies on many parameters—geometry, wavelength and initial field distribution, material data, and electrooptic driving conditions. These parameters must be optimized before fabricating a device. With large-scale optoelectronic circuits, accurate modeling is predominant because of the numerous resources required to fabricate a chip.

Optical waveguide design relies on simulating the propagation of light signals, waveguide modes, mode coupling, and loss and gain. One part of the entry data defines the waveguide device by its geometry, fabrication parameters, and material constants. It is best to entered the waveguide data using software with a project layout that can also handle fabrication parameters. Another part of entry data is for configuring numerical calculations. Ideally, entry systems hide or limit the details of the numerical calculation. However, because waveguide modeling often uses sophisticated numerical algorithms, you must be familiar with some aspects of the underlying numerics.

Waveguides are the building blocks of photonic circuits. The width of a waveguide (constant or variable) is defined as perpendicular to the path along the waveguide center.