Fiber optic measurements are necessary and must be performed by component manufacturers and end users if data links are to operate reliably. Manufacturers must test how component designs, material properties, and fabrication techniques affect the performance of fiber optic components.
These tests can be categorized as design tests or quality control tests. Design tests are conducted during the development of a component. Design tests characterize the component's performance (optical, mechanical, and environmental) in the intended application.
Once the component performance is characterized, the manufacturer generally only conducts quality control tests. Quality control tests verify that the parts produced are the same as the parts the design tests were conducted on. When manufacturers ship fiber optic components, they provide quality control data detailing the results of measurements performed during or after component fabrication.
End users (equipment manufacturers, shipbuilders, maintenance personnel, test personnel, and so on)should measure some of these parameters upon receipt before installing the component into the fiber optic data link. These tests determine if the component has been damaged in the shipping process.
In addition, end users should measure some component parameters after installing or repairing fiber optic components in the field. The values obtained can be compared to the system installation specifications. These measurements determine if the installation or repair process has degraded component performance and will affect data link operation.
Whenever a fiber optic measurement is made, it should be made using a standard measurement procedure. For most fiber optic measurements, these standard procedures are documented by the Electronics Industries Association/Telecommunications Industries Association (EIA/TIA). Each component measurement procedure is assigned a unique number given by EIA/TIA-455-X. The X is a sequential number assigned to that particular component test procedure. System level test procedures are assigned unique numbers given by EIA/TIA-526-X. Again the X is a sequential number assigned to that particular system test procedure.
LABORATORY FIBER OPTIC MEASUREMENTS
Providing a complete description of every laboratory measurement performed by manufacturers and end users is impossible. This section only provides descriptions of optical fiber and optical connection measurements that are important to system operation. The list of optical fiber and optical connection laboratory measurements described in this chapter includes the following:
· Cutoff wavelength (single mode)
· Bandwidth (multimode)
· Chromatic dispersion
· Fiber geometry
· Core diameter
· Numerical aperture (multimode)
· Mode field diameter (single mode)
· Insertion loss
· Return loss and reflectance
End users routinely perform optical fiber measurements to measure fiber power loss and fiber information capacity. End users may also perform optical fiber measurements to measure fiber geometrical properties. Optical fiber power loss measurements include attenuation and cutoff wavelength.
Optical fiber information capacity
measurements include chromatic dispersion and bandwidth. Fiber
geometrical measurements include cladding diameter, core diameter,
numerical aperture, and mode field diameter. Optical connection
measurements performed by end users in the laboratory include insertion
loss and reflectance or return loss.
Fiber Optic Attenuation
Fiber Optic Bandwidth and Chromatic Dispersion
Numerical Aperature and the Mode Field Diameter
Insertion Loss, Return Loss, and Reflectance
Optical Time Domain Reflectometry