{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Optical Networks - _3_8 Wavelength Converters_42

Optical Networks - _3_8 Wavelength Converters_42 - 3.8...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
3.8 Wavelength Converters 221 the interconnections are not difficult. However, practical considerations of power dissipation and board space dictate the necessity for having multiple printed circuit boards and perhaps multiple racks of equipment. The interconnects between these boards and racks need to operate at the line rate, which is typically 2.5 Gb/s or higher. High-quality electrical interconnects or optical interconnects can be used for this purpose. The drivers required for the electrical interconnects also dissipate a significant amount of power, and the distances possible are limited, typically to 5– 6 m. Optical interconnects make use of arrayed lasers and receivers along with fiber optic ribbon cables. These offer lower power dissipation and significantly longer reach between boards, typically to about 100 m or greater. 3.8 Wavelength Converters A wavelength converter is a device that converts data from one incoming wave- length to another outgoing wavelength. Wavelength converters are useful compo- nents in WDM networks for three major reasons. First, data may enter the network at a wavelength that is not suitable for use within the network. For example, the first-generation networks of Chapter 6 commonly transmit data in the 1310 nm wavelength window, using LEDs or Fabry-Perot lasers. Neither the wavelength nor the type of laser is compatible with WDM networks. So at the inputs and outputs of the network, data must be converted from these wavelengths to narrow-band WDM signals in the 1550 nm wavelength range. A wavelength converter used to perform this function is sometimes called a transponder. Second, wavelength converters may be needed within the network to improve the utilization of the available wavelengths on the network links. This topic is studied in detail in Chapter 10. Finally, wavelength converters may be needed at boundaries between different networks if the different networks are managed by different entities and these entities do not coordinate the allocation of wavelengths in their networks. Wavelength converters can be classified based on the range of wavelengths that they can handle at their inputs and outputs. A fixed-input, fixed-output device always takes in a fixed-input wavelength and converts it to a fixed-output wavelength. A variable-input, fixed-output device takes in a variety of wavelengths but always converts the input signal to a fixed-output wavelength. A fixed-input, variable-output device does the opposite function. Finally, a variable-input, variable-output device can convert any input wavelength to any output wavelength. In addition to the range of wavelengths at the input and output, we also need to consider the range of input optical powers that the converter can handle, whether the converter is transparent to the bit rate and modulation format of the input signals,
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
222 Components and whether it introduces additional noise or phase jitter to the signal. We will see that the latter two characteristics depend on the type of regeneration used in the converter. For all-optical wavelength converters, polarization-dependent loss should
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern