We all are familiar with laser and its applications. Lasers have a very important role in the health care industry. Also lasers are used in the communication field also. For instance, the wavelength of the light from the laser depends on the material of laser. Can you adjust the wavelength of the laser? This is possible by using a tunable laser.
Tunable lasers as the name suggests are lasers whose wavelengths are often tuned or varied. Also they play a very important role in optical communication networks. Moreover, recent enhancements in tunable laser technologies are enabling highly flexible and effective utilization of the huge increases in optical network capability brought by large-scale application of dense wavelength division multiplexing.
Several tunable laser technologies have emerged, each having its own set of tradeoffs with reference to the requirements of specific optical networking applications.
Tunable lasers are made mainly in four ways:
- The external cavity laser
- The vertical cavity laser
- Distributed feedback laser (DFB)
- Micro electro mechanical system (MEMS)
Tunable lasers facilitate network administrators to avoid wasting plenty of cost, by permitting them to efficiently manage the network with lesser number of spares. They also modify reliable functioning of the optical network. Changing traffic patterns, client necessities, and new revenue opportunities need larger flexibility than static OADMs will offer, complicating network operations and planning. Incorporating tunable lasers removes this constraint altogether by permitting any channel to be superimposed by the OADM at any time.
Tunable lasers are still a comparatively young technology, but as the range of wavelengths in networks will increase their importance. Every different wavelength in an optical network is going to be separated by a multiple of 0.8 nanometers. Current industrial products will cover maybe four of these wavelengths at a time. While not the perfect solution, this still cuts your needed range of spare lasers down.
Lasers are devices giving out intense light at one specific color. The types of lasers utilized in optical networks are small devices – typically regarding the dimensions of a grain of salt. They’re little pieces of semiconductor material, specially designed to give out very precise and intense light. Inside the semiconductor material are many electrons – negatively charged particles.
The devices themselves are still semiconductor-based lasers that operate on similar principles to the fundamental non-tunable versions. Most designs incorporate some variety of gratings like those in a distributed feedback laser. These gratings may be altered in order to vary the wavelengths they reflect in the laser cavity. Typically by running current through them, thereby altering their index of refraction.
The tuning range of such devices is often as high as 40nm, which might cover any of 50 different wavelengths in a 0.8nm wavelength system. Technologies that are based on vertical cavity surface emitting lasers (VCSELs) incorporate movable cavity ends that modify the length of the cavity and thus the wavelength emitted. Moreover, Designs of tunable VCSELs have similar tuning ranges.
Let us see some of the applications of tunable lasers:
- Tunable lasers are used in spectroscopy.
- In laser isotope separation
- Used for device characterization
- Used in optical fiber communication and wavelength division multiplexing, optical frequency metrology
- It is used in fiber optic sensors and interferometers