Hello.

As far as tunable lasers are concerned i want to mention that Tunable lasers have been the subject of considerable interest ever since the start of the wavelength division multiplexing (WDM) revolution. In this paper, we bring together views on tunable lasers from different types of companies in the value chain, from operators to laser manufacturers. The purpose is to give an overview of the state of the art in both deployment and development, as well as to try to predict trends over the coming years. A tunable laser is a laser whose wavelength of operation can be altered in a controlled manner. While all laser gain media allow small shifts in output wavelength, only a few types of lasers allow continuous tuning over a significant wavelength range.There are many types and categories of tunable lasers. They exist in the gas, liquid, and solid state. Among the types of tunable lasers are excimer lasers, gas lasers (such as CO2 and He-Ne lasers), dye lasers (liquid and solid state), transition metal solid-state lasers, semiconductor crystal and diode lasers, and free electron lasers. Tunable lasers find applications in spectroscopy,photochemistry, atomic vapor laser isotope separation, and optical communications.
I am providing link of a paper you may refer to it.
https://www.osapublishing.org/jlt/abstract.cfm?uri=jlt-24-1-5
The purpose of the paper is to give an overview of the state of the art in both deployment and development, as well as to try to predict trends over the coming years.

Thanks