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There are two commonly used types of optical modulators in fiber optic communication systems: the electroabsorption modulator (EAM) and the Mach-Zehnder modulator (MZM). Electroabsorption Modulator (EAM) EAM is small and can be integrated with the laser on the same substrate. An EAM combined with a CW laser source is known as an electroabsorption modulated laser. An EML consist of a CW DFB laser followed by an EAM, as shown above. Both devices can be integrated monolithically on the same InP substrate, leading to a compact design and low coupling losses between the two devices. The EAM consists of an active

In the last several years, FTTH installation, led by Verizon, has become really hot. But traditionally, there is one big issue where fiber lags behind copper cable: macro bending loss. Traditionally, fiber cables must be handled and installed very carefully to avoid small bends along the fiber path, which can cause signal loss. This is especially true for indoor installations where contract installers encounter many sharp turns. Several approaches have been designed to reduce the bend performance of optical fibers. 1. Reducing the mode field diameter 2. Depressing the cladding 3. Adding a low index trench However, these enhancing options

As most fiber optic cable installers know, the labor and costs associated with accessing and grounding a traditional armored fiber optic cable is pretty high. Because the armor is usually made of aluminum foil or steel, so grounding is a must for all installations. On April 6, 2009 Corning Cable Systems introduced its MIC DX serials all-dielectric armored fiber cable. This completely removes the need to ground the cable. As described by Corning, the cable core is protected by a flexible all-dielectric armor, that offers more than 4 times the crush protection compared to regular unarmored fiber cables. The

What is VCSEL? VCSEL stands for Vertical-Cavity Surface-Emitting Laser. It is a type of semiconductor laser diode with laser beam emission perpendicular from the top surface, contrary to conventional edge-emitting semiconductor lasers which emit from surfaces formed by cleaving the individual chip out of a wafer. Advantages of VCSEL laser  A typical VCSEL consists of two oppositely-doped distributed Bragg reflectors (DBR) with a cavity layer between. In the center of the cavity layer resides an active region, consisting of multiple quantum wells. Current is injected into the active region via a current guiding structure either provided by an oxide aperture

EDFAs consist of erbium-doped fiber having a silica glass host core doped with active Er ions as the gain medium. Erbium-doped fiber is usually pumped by semiconductor lasers at 980nm or 1480nm.   Basic elements of an EDFA are shown in the figure above. The gain medium in the amplifier is a specially fabricated optical fiber with its core doped with erbium(Er). The erbium-doped fiber (EDF) is pumped by a semiconductor laser, which is coupled by using a wavelength selective coupler, also known as a WDM coupler, that combines the pump laser light with the signal light. The pump light