liquid laser[′lik·wəd ′lā·zər]
a laser with a liquid active material. The advantage of a liquid laser is the feasibility of cooling the liquid by circulation. This permits production of higher energy both in pulsed and continuous operation.
In the first liquid lasers solutions of rare-earth chelates were used. They have not yet found application because of the low attainable energy and the insufficient stability of the chelates. Liquid lasers using inorganic active liquids (proposed and synthesized in the USSR) have high pulse energies at considerable mean power. In addition liquid lasers generate radiation with a narrow frequency spectrum.
Liquid lasers using solutions of organic dyes have some interesting properties. The broad spectral lines of organic dyes permit the construction of a liquid laser with continuous tuning of the emitted wavelength within a range of several hundreds of A. By changing the dyes, the whole visible spectrum and a part of the infrared spectrum can be covered. Liquid dye lasers usually use solid lasers as a pumping source. Some dyes can be pumped by special flash fluorescent lamps, which give shorter and more intensive flashes of white light than are given by the usual flash lamps (less than 50 microseconds).
M. E. ZHABOTINSKII