"An important element of telecommunications component modeling is the ability to simulate sources and components in order to optimize the efficiencies-or power transfer-between these systems. For example, it is very important to maximize the amount of power coupled from the laser into a single-mode fiber to minimize power loss. To do so, the mode of a laser diode and coupling system should match the mode of the single-mode fiber it is entering. This calculation is called the coupling coefficient calculation and is dependent on a number of parameters associated with the source, the coupling optics, and the fiber.
Fortunately there are common threads that bind the calculation of the system`s coupling coefficient together. These common threads are found in fundamental characteristics that specify the behavior of electromagnetic radiation-coherence, polarization, amplitude, and phase.
Calculating coupling efficiencies is important not only in the case of a single-mode fiber but for other components such as spectrally tuned WDM systems. Coupled fields and coupling coefficients can be computed in some but not all commercially available software programs.
The technique used in ASAP™ Breault Research Organization; Tucson, AZ) to simulate the coherence, polarization, amplitude, and phase of diffracting sources like laser diodes-and in general other physical optics phenomena-is called Gaussian beam superposition. The Gaussian beam superposition algorithm models arbitrary optical fields as a summation of fundamental Gaussian beams. The superposition algorithm is similar to Babinet`s principle except that Gaussian beams are used as the basis functions (Babinet's principle states that the diffraction patterns produced by complementary screens are identical). ..."
Copyright 2000, PennWell Corporation. Reprinted from the August 2000 issue of WDM Solutions. Copyright does not allow for printing of this article. If you would like a printed copy, please email your request to firstname.lastname@example.org.