Dye Lasers

A dye laser is a laser that uses an organic dye as its gain medium. The dye is usually dissolved in a solvent, such as ethanol, and is pumped by a laser beam to produce laser action. The wavelength of the laser light is determined by the properties of the dye, and can be tuned by changing the dye.

Dye lasers were some of the first lasers to be developed, and were used extensively in early research on lasers. They are now used in a wide range of applications, including medical diagnosis and treatment, materials processing, and scientific research.

The operating principle of a dye laser is relatively simple. The laser beam pumps energy into the dye molecules, which then fluoresce, or emit light. The emitted light is amplified by stimulated emission, and the laser beam is produced.

Dye laser alignment intra-cavity beam @ 589nm — The internal cavity of a Coherent Inc. model 740 dye laser is exposed during alignment of the optics. The frequency-doubled Nd:YAG laser enters the dye cell from the left, to “pump” the dye into a fluorescent state, where it will be ready to emit stimulated radiation. The fluorescence from the dye is reflected between the end mirrors, which consists of a diffraction grating (upper left of center) on one end of the beam and a cavity dumper, in the form of an acousto-optic modulator (beyond the right edge), on the other end, which is used as the output coupler. The beam goes through several stages of expansion, folding and contraction using a variety of curved mirrors, flat mirrors and prisms, adjusting it to the optimum size for each stage of the cavity. The cavity length is 1.97 meters, although the mirrors allow for it to be mounted in a shorter case. The dye cell is placed closer to one end of the cavity, because two waves are emitted from the cell in opposite directions. In this way, the wave on the shorter end of the cavity returns to the dye cell first, using most of its energy, and the other wave is eventually extinguished. This allows full gain from only one wave and a very short pulse of light can be extracted. The laser is capable of continuous wave operation or ultrafast picosecond pulses. The laser was photographed during a mirror-alignment procedure, allowing better imaging of the beam. The external laser used for alignment is 589 nm and is much brighter than the actual beam would be. The pump laser is shown for demonstration purposes, but at very low power (30 mw) in order to match the brightness of the 50 mw yellow beam. (In normal operation the pump laser would be much brighter than the intra-cavity beam, making it very difficult to photograph.

The wavelength of the laser light is determined by the properties of the dye molecules. The dye molecules can be designed to absorb light at a specific wavelength, and then emit light at a different wavelength. By carefully selecting the dye molecules, the wavelength of the laser light can be tuned over a wide range.

Dye lasers are used in a wide range of applications. They are particularly well suited for medical applications, due to their ability to produce laser light at specific wavelengths. Dye lasers are used for medical diagnosis, such as cancer detection, and for treatment, such as laser surgery.

Dye lasers are also used in materials processing. They are used to cut and weld materials, and to drill holes. Dye lasers can also be used to write and read data on optical discs.

Dye lasers are also used extensively in scientific research. They are used to study the properties of materials, and to investigate the fundamental principles of physics. Dye lasers are also used to generate high-intensity laser beams for experiments in nuclear fusion and other areas of research.

Dye lasers are also used in materials processing. They are used to cut and weld materials, and to drill holes. Dye lasers can also be used to write and read data on optical discs.