Fiber Optic Tutorials

This is a continuation from the previous tutorial - laser output-beam properties.   Let us look at just a few practical examples of real lasers that illustrate some of the points we have been discussing, notably the ruby solid-state laser, and the helium-neon gas laser.   The Ruby Laser The first laser of any type ever to be operated was in fact the flash-pumped ruby laser demonstrated by T. H. Maiman at the Hughes Research Laboratory in early 1960. We have already shown in Figure 1.10 [refer to the atomic energy levels and spontaneous emission tutorial] the quantum energy levels...

This is a continuation from the previous tutorial - materials and fabrication technologies in optical fiber manufacturing.   The output beam from a laser oscillator thus basically consists of electromagnetic radiation, or light, that is not fundamentally different in kind from the radiation emitted by any other source of electromagnetic radiation. There are several important and fundamental differences in detail, however, between the "incoherent" light emitted by any thermal light source, such as the flashlight in Figure 1.42, and the "coherent" light emitted by a laser oscillator.   Figure 1.42  Incoherent light from a flashlight (top) and coherent light from a...

This is a continuation from the previous tutorial - fiber nonlinearities.   Double Crucible Technique The first attempt at producing high-purity glass, the so-called ‘‘double-crucible technique,’’ proceeded along the lines of conventional glass melting but used specially prepared constituents. Soda-lime-silicate and sodium-borosilicate glasses were made from materials purified to parts-per-billion (ppb) levels of transition metal impurities by ion exchange, electrolysis, recrystallization, or solvent extraction. These starting glasses were melted, fined, drawn to cane, and fed into an ingenious continuous casting system composed of concentric platinum crucibles, shown in Fig. 3.1. A thin stream of core glass flowed from the upper...

This is a continuation from the previous tutorial - Gaussian analysis of afocal lenses.   Overview Highly focused coherent laser light, propagating with low loss through optical fiber over long distances (kilometers), is an ideal breeding ground for nonlinear interaction with the glass material. Although nonlinear effects were found in early optical transmission work with analog signal delivery (CATV, etc.), much attention lately has been given to resolution of nonlinear problems in long-haul optical communications and high-power operation in specialty fibers. In particular, new fiber types have been developed to overcome nonlinear impairments. As fiber design introduced dispersion-shifted fibers (DSFs)...

This is a continuation from the previous tutorial - rapid estimation of lens performance.   Introduction If collimated (parallel) light rays from an infinitely distant point source fall incident on the input end of a lens system, rays exiting from the output end will show one of three characteristics: They will converge to a real point focus outside the lens system. They will appear to diverge from a virtual point focus within the lens system. They will emerge as collimated rays that may differ in some characteristics from the incident collimated rays. In cases 1 and 2, the paraxial imaging properties...