Go to GlobalSpec.com Home
Newsletter   FREE GlobalSpec e-Newsletters
Receive the latest news, trends, and technology relevant to your work.
(See Titles)

Chapter 9.1 - Basic WDM Scheme

By Govind P. Agrawal
From Lightwave Technology

9.1 Basic WDM Scheme

The WDM technique corresponds to the scheme in which the capacity of a lightwave system is enhanced by employing multiple optical carriers at different wavelengths. Each carrier is modulated independently using different electrical bit streams (which may themselves use TDM and FDM techniques in the electrical domain) that are transmitted over the same fiber. Figure 9.1 shows schematically the layout of such a dispersion-managed WDM link. The output of several transmitters is combined using an optical device known as a multiplexer. The multiplexed signal is launched into the fiber link for transmission to its destination, where a "demultiplexer" separates individual channels and sends each channel to its own receiver. The implementation of such a WDM scheme required the development of many new components such as multiplexers, demultiplexers, and optical filters (see Chapter 8 of LT1), all of which became available commercially during the 1990s.

09_01_00_Lightwave_Technology-1.jpg

Figure 9.1: Schematic of a WDM fiber link. Each channel operates at a distinct wavelength through transmitters operating at different wavelengths. Pre-, post-, and in-line compensators are used to manage the dispersion of fiber link.

© 2005 John Wiley & Sons, Inc.

Products & Services
Fiber optic linear position sensors use fiber optic technology to sense position and displacement. Search by Specification | Learn more about Fiber Optic Linear Position Sensors
Fiber optic couplers are optical devices that connect three or more fiber ends, dividing one input between two or more outputs, or combining two or more inputs into one output. Search by Specification | Learn more about Fiber Optic Couplers
Fiber optic wiring accessories are used to connect, adapt, polish, repair, fiber and fiber optic cables. This area includes fiber optic consumables such as polish, swabs, wipes, etc. Learn more about Fiber Optic Wiring Accessories
Fiber optic transceivers include both a transmitter and a receiver in the same component. Search by Specification | Learn more about Fiber Optic Transceivers
Fiber optic cables are composed of one or more transparent optical fibers enclosed in protective coverings and strength members. Fiber optic cables are used to transmit "light" data. Search by Specification | Learn more about Fiber Optic Cables

Product Announcements
Advanced Photonix, Inc.® - Photopic Filtrode Photodiode Chip
The Photopic Filtrode Photodiode chip was designed to mimic the response of the human eye. The part is a standard Blue- Enhanced photodiode that has a filter applied to it using an API patented... (read more)
Larox Corporation - Scheibler A Series Polishing Filters from Larox
Specifically designed for Chemical Processing Industry applications, the Larox A Series Polishing Filter family is customized to meet the industry needs including inorganic pigments, pulp and paper,... (read more)
California Eastern Laboratories - CEL - PS9121 High Speed Digital SOP5 Optocoupler
The PS9121 is high speed digital otpocoupler in SOP5 package, providing 3,750V isolation. the output is active low Open Collector, with a photodiode and a signal processing circuit on the output side... (read more)
California Eastern Laboratories - CEL - PS9117A High Speed Digital Optocoupler
PS9117A a high speed digital optocoupler with 3,750V isolation, active low Open Collector output. A photodiode and a signal processing circuit on the output side of one chip provide excellent... (read more)
OSI Optoelectronics - Large Area Photodiodes
FCI-InGaAs-XXX-X series with active area sizes of 1mm, 1.5mm and 3mm, are part of OSI Optoelectronics' large active area IR sensitive detectors which exhibit excellent responsivity from 1100nm to... (read more)
Melexis, Inc. - Integrated Light Sensor Exceeds 15 Year Lifetime
The MLX75305 Light-to-Voltage SensorEyeCTM is an integrated sensor IC specifically designed for high volume automotive, industrial and consumer applications. The light sensor's output gives a voltage... (read more)

Topics of Interest
9.1.1 System Capacity and Spectral Efficiency It is evident from Figure 9.1 that the use of WDM can increase the system capacity because it transmits multiple bit streams over the same fiber... (Read More)
Avago Technologies has introduced a new color sensor ADJD-E622-QR999, designed specifically for automotive applications. It is built to meet the Automobile Electronics Council AEC-Q100 standards. This... (Read More)
4.4 Signal Conditioning High Impedance Sensors Many popular sensors have output impedances greater than several M ?, and the associated signal conditioning circuitry must be carefully designed to... (Read More)
Absorption: The portion of optical attenuation in an optical fiber resulting from the conversion of optical power to heat; caused by impurities such as hydroxyl ions in the fiber. A/B Switch: A... (Read More)
  Schottky Photodiode The PIN and avalanche photodiodes discussed in the previous two sections are both p-n-junction-based devices. In contrast, the Schottky photodiode utilizes a... (Read More)