>> What is Power over Ethernet? 1. Introduction Power-over-Ethernet (PoE) or "Active Ethernet" eliminates the need to run 110/220 VAC power to Wireless Access Points and other devices on a wired LAN. Using Power-over-Ethernet system, installers need to run...
In the past, companies often had several cabling infrastructures because no single cabling system would support all of a company’s applications. Nowadays, a standardized cabling system is important not only for consumers but also for vendors and cabling installers. Vendors...
>> What is AWG? A remarkable device that has been made using several planar-waveguide technologies and has found a variety of applications in WDM lightwave systems is the arrayed-waveguide grating, or AWG. Arrayed-waveguide gratings (AWG) are based on the...
>> Background History of Optical Circulator An optical circulator is a multi-port (minimum three ports) nonreciprocal passive component. The function of an optical circulator is similar to that of a microwave circulator—to transmit a lightwave from one port...
>> A Brief Introduction to Optical Amplifiers Because fiber attenuation limits the reach of a nonamplified fiber span to approximately 200 km for bit rates in the gigabit-per-second range, wide area purely optical networks cannot exist without optical...
>> The Basics of Quantum Wells Lasers Regular double heterostructure (DH) semiconductor lasers have an active region of 0.1 to 0.2um thick. Since the 1980s, lasers with very thin active regions, quantum well lasers, were being developed in many research...
>> The Background In recent years there has been a lot of work on dispersion-compensating fibers (DCFs), which are being used extensively for upgrading the installed 1310nm optimized optical fiber links for operation at 1550nm. In the following two sections,...
>> The Birefringence of Single Mode Fiber Circular core fibers whose axes are straight are not birefringent – that is, the two orthogonally polarized LP01 mode have the same effective indices. Bending such a fiber introduces stresses in the...
>> Effective Length Le The nonlinear interactions in optical fibers depends on the transmission length and the cross-sectional area of the fiber. The longer the link length, the more...
The effect of nonlinearities can be reduced by designing a fiber with a large effective area. Non-Zero Dispersion Shifted fibers (NZ-DSF) have a small value of the chromatic dispersion in the 1550nm band to minimize the effects of...
================================================================================================ Frequency dispersion in groups of gravity waves on the surface of deep water. The red dot moves with the phase velocity, and the green dots propagate with the group velocity. In this deep-water case, the...
>> What is exactly PCM? Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as...
>> Nonlinear Effects in High Power, High Bit Rate Fiber Optic Communication Systems When optical communication systems are operated at moderate power (a few milliwatts) and at bit rates up to about 2.5 Gb/s, they...
>> What is Jitter and Wander? 1. Jitter: Jitter is the short-term phase variations of the significant instants of a digital signal from their ideal positions in time. It is the deviation of the significant instants of...
Most semiconductor lasers have cleaved facets that form the optical cavity. The facets are perpendicular to the surface of the wafer and light is emitted parallel to the surface of the wafer. But for many applications requiring a two-dimensional laser array or...