What is a Dye Laser?

A laser which efficiently uses an organic dye as its active lasing medium (usually a liquid solution) can be termed as a dye laser. Organic dye or any other kind of dye holds the capability to absorb light through definite wavelengths which further corresponds to particular electronic transitions. Dye laser also emits laser gain and fluorescence, and are also used for wider range of wavelengths which can span up to 50 to 100 nanometers or more. Dye lasers can be promoted to tunable lasers and pulsed lasers with the assistance of wide bandwidth which makes them suitable for the upgrade.

In order to generate an extensive range of wavelengths from the same laser, by replacing the dye from near-ultraviolet to near-infrared is done by replacing additional optical components residing in the laser itself. Dye Lasers are capable in producing output whose wavelengths lie in the near visible infrared spectrum and ultraviolet spectrum. The concept of dye laser was discovered chiefly by F.P. Schafer and P.P. Sorokin in the year of 1966.

Characteristics of Dye Lasers:

Dye lasers represent a comprehensive gain bandwidth which further permits ultra-short pulse generation accompanied with passive mode locking and broad wavelength tunability.
Gain per unit length is objectively high i.e. of order 10^3 cm^-1 which is principally used for pulsed pumping.
The upper-state lifetimes are usually a couple of nanoseconds which lies close to the value of semiconductor lasers.
Output power of dye lasers considerably starts from 1 Watt with no theoretic upward limit.
Magnitude of dye lasers is shorter than doped-insulator lasers.
Dye Lasers besides being available in their usual liquid state are also available in the form of solid state dye lasers or commonly referred as SSDL.
Q-Switching- Dyes are not an appropriate choice for Q-Switching with long-pulse pumping. On the other hand, powerful dye laser pulses can be gained using pulsed pumping and a flash lamp or a switched pump laser.
The beam quality of dye lasers is potentially over tens of nanometers.
Power conversion efficiency of dye laser ideally lies in between 10% to 30% for laser pumping and even much lower for flash lamp pumping.

Applications of Dye Lasers:

Dye lasers through their standard wavelength agility are capable in offering extremely high average powers as well as large pulsed energies. Dye lasers are used primitively in fields like medicine, astronomy, spectroscopy, manufacturing and atomic vapor laser isotope segregation.

Medicine: Dye Lasers play an important role in dermatology to make the skin tone even. Dye Lasers are able to match to the absorption lines of particular tissues like hemoglobin and melanin which again is the contribution of wide range of wavelengths possible. On the other hand, the narrow bandwidth of dye laser aids any possibilities of damage caused to the surrounding tissues. Many other issues like blood vessel disorders, scars, port-wine stains and kidney stones become curable with the help of dye lasers.

Spectroscopy: Dye Lasers comes to the rescue when detailed study of absorption and emission spectra of countless materials comes into picture. The most petitioning factors of dye lasers that allow superior diversity than other light sources are high intensity, narrow bandwidth and their tunability. Diversity of pulse widths, femtosecond pulses, continuous wave operation and ultra-short makes dye lasers suitable for an extensive array of applications.

Pros of Dye Lasers:

A variety of wavelengths can be produced with the assistance of dye lasers.
Easy to construct.
The beam divergence of dye lasers is way to less than many other lasers beams. It ranges from 0.8 milli radians to 2 milli radians.
Superior efficiency of 25%.
Dye lasers can generate high output power.
Accessible in both visible and non-visible form.
Less beam diameter.

Cons of Dye Lasers:

Escalated cost of dye lasers is a subject.
Due to the complex formula of dye, the determination of the element that lases is a complex.
In order to tune at a single frequency, the dye laser uses birefringent element or a filter which makes it costly.

Dye lasers are used in multiple forms. Few examples of dye lasers are Rhodamine 6G, Sodium fluoresein and Rhodamie B which uses liquid material i.e. die as its active medium to produce laser light.