Tunable lasers as the name suggests are lasers whose wavelengths can be tuned or varied. They play an important part in optical communication networks. Recent improvements in tunable laser technologies are enabling highly flexible and effective utilization of the massive increases in optical network capacity brought by large-scale application of dense wavelength division multiplexing.
Description of Tunable Lasers
Several tunable laser technologies have emerged, each with its own set of tradeoffs with respect to the needs of particular optical networking applications. Tunable lasers are produced mainly in 4 ways: The distributed feedback laser (DFB), the external cavity diode laser, the vertical cavity diode laser and the micro electro mechanical system (MEMS) technology. Tunable lasers help network administrators to save a lot of cost, by allowing them to efficiently manage the network with lesser number of spares.
They also enable reliable functioning of the optical network. Changing traffic patterns, customer requirements, and new revenue opportunities require greater flexibility than static OADMs can provide, complicating network operations and planning. Incorporating tunable lasers removes this constraint altogether by allowing any channel to be added by the OADM at any time.In a wavelength-division multiplexed (WDM) network carrying 128 wavelengths of information, we have 128 different lasers giving out these wavelengths of light. Each laser is designed differently in order to give the exact wavelength needed. Even though the lasers are expensive, in case of a breakdown, we should be able to replace it at a moment's notice so that we don't lose any of the capacity that we have invested so much money in.
So we keep in stock 128 spare lasers or maybe even 256, just to be prepared for double failures.What if we have a multifunctional laser for the optical network that could be adapted to replace one of a number of lasers out of the total 128 wavelengths? Think of the money that could be saved, as well as the storage space for the spares. What is needed for this is a "tunable laser".