The plot of optical output (L) as a function of current (I) which characterizes an electrical-to-optical converter. A typical L-I curve is shown at right.
An emitter that radiates according to Lambert’s cosine law, which states that the radiance of certain idealized surfaces depends on the viewing angle of the surface. The radiant intensity of such a surface is maximum normal to the surface and decreases in proportion to the cosine of the angle from the normal. Given by:
N = N0cosA
N = radiant intensity
N0 = radiance normal to an emitting surface.
A = angle between the viewing direction and the normal to the surface.
Acronym for light amplification by stimulated emission of radiation. A light source that produces, through stimulated emission, coherent, near monochromatic light.
A semiconductor that emits coherent light when forward biased.
An optical fiber used to couple and condition light from an optical source into an optical fiber. Often the launch fiber is used to create an equilibrium mode distribution in multimode fiber. Also called launching fiber.
In a binary code, the bit or bit position assigned to the smallest quantity or increment that can be represented by the code.
A local telephone company, i.e., a communications common carrier that provides ordinary local voice-grade telecommunications service under regulation within a specified service area.
In a strict sense, the region of the electromagnetic spectrum that can be perceived by human vision, designated the visible spectrum, and nominally covering the wavelength range of 0.4 um to 0.7 um. In the laser and optical communication fields, custom and practice have extended usage of the term to include the much broader portion of the electromagnetic spectrum that can be handled by the basic optical techniques used for the visible spectrum. This region has not been clearly defined, but, as employed by most workers in the field, may be considered to extend from the near-ultraviolet region of approximately 0.3 um, through the visible region, and into the mid-infrared region to 30 um.
Use of optical fibers to illuminate.
The path of a point on a wavefront. The direction of the lightwave is generally normal (perpendicular) to the wavefront.
The basic measurement of how well analog-to-digital and digital-to-analog conversions are performed. To test for linearity, a mathematically perfect diagonal line is converted and then compared to a copy of itself. The difference between the two lines is calculated to show linearity of the system and is given as a percentage or range of least significant bits.
1. In public switched networks, regarding circuits that span long distances, such as the circuits in inter-LANA, interstate, and international communications. 2. In military use, communications among users on a national or worldwide basis. Long-haul communications are characterized by a higher level of users, more rigorous performance requirements, longer distances between users, including world wide distances, higher traffic volumes and densities, larger switches and trunk cross sections, and fixed and recoverable assets. Usually pertains to the U.S. Defense Communications System.
1) A communication channel from a switching center or an individual message distribution point to the user terminal (illustrated). 2) In telephone systems, a pair of wires from a central office to a subscriber’s telephone. 3) A type of antenna used extensively in direction-finding equipment and in UHF reception.
1) Reduction of the storage size of digital data by employing one or more appropriate algorithms in such a way that the data can be recover without loosing integrity. 2) Reduction of the amount of data that needs to be transmitted per unit time though an analogous real-time process that does not compromise the ability to completely restore the data.
Reduction of the bit-rate for an image signal by using algorithms that achieve a higher compression than lossless compression. Lossy compression presents loss of information and artifacts that can be ignore when comparing to original image. Lossy compression takes advantage of the subtended viewing angle for the intended display, the perceptual characteristics of the human eye, the statistics of image populations, and the objective of the display. 2) Removal of redundant bits from an image in video technology producing a minor loss of image quality.