Novel gain measurement technique for high gain amplifiers

A new method for determining the gain in high gain amplifiers is reported. The technique only requires measurements of the relative intensity and the output spectral width of the amplified spontaneous emission from the amplifier as a function of input pumping. The results of an experimental test of this technique using a flashlamp-pumped rhodamine 6G dye amplifier are described. Simple approximate analytical models are used to compare with experiment thereby determining the gain. The results are found to be in good agreement with both more accurate gain measurements and an alternative technique which can be applied over a restricted range of operational parameters.