Archived — Fiber Optic Technology

Polarization-dependent loss (PDL) for a component or system is the maximum, peak-to-peak insertion  loss (or gain) variation caused by a component when stimulated by all possible polarization states  (see Figure 1). It is specified in dB units. Polarization-dependent loss may also be referred to as  polarization sensitivity, polarization-dependent gain (PDG) or extinction ratio (for optical polarizers). Some components are designed for maximum PDL. A linear optical polarizer, for example,  must have high PDL in order to convert un-polarized light into linearly polarized light. Only one  orientation of linearly polarized light passes through the polarizer un-attenuated. Misaligned orientations  of polarized light

Why line coding ? There are many reasons for using line coding. Each of the line codes you will be examining offers one or more of the following advantages: Spectrum shaping and relocation without modulation or filtering. This is important in telephone line applications, for example, where the transfer characteristic has heavy attenuation below 300 Hz. Bit clock recovery can be simplified. DC component can be eliminated; this allows AC (capacitor or transformer) coupling between stages (as in telephone lines). Can control baseline wander (baseline wander shifts the position of the signal waveform relative to the detector threshold and leads

Theory When two single mode fibers are butted together to form a joint, the fundamental mode field of the source fiber is coupled into the modes of the recipient fiber. These recipient modes consist of the fundamental mode, lossy cladding modes and radiation modes. The magnitude of the source mode field coupled into each recipient mode is given by the overlap integral of the two modal electric fields. In the transverse offset technique, we are concerned with the transfer of optical power from the source mode into the same mode of an identical fiber when their axes are parallel but

Theory The direct far-field scanning technique measures the angular distribution of the far-field intensity distribution from the single mode fiber, F( p)2 .The variable aperture technique also measures power in the far-field but rather than making a continuous measurement of the intensity distribution, the total power passing through a set of circular apertures is measured. It is assumed that the far-field and therefore the fiber are rotationally symmetric. The apertures are centred on the optical axis of the fiber so that they are also centred on the axis of rotational symmetry of the far-field pattern. For a circular aperture of

The reason that fiber Ethernet ports can only transmit at one speed is that different light sources are utilized for each of the Ethernet configurations. 10Mbps Ethernet over fiber uses an 850nm LED (Light Emitting Diode), 100Mbps uses a 1300nm LED and 1000Mbps (1Gbps) uses a VCSEL (vertical Surface Emitting LASER). If a fiber port was capable of transmitting at all of these speeds each port would require three separate light sources which is not feasibly economic. Make sure that the port speeds are the same when connecting fiber switch ports. Also note it is recommended to always use LASER