Solid-state laser wavelength identification using a reference absorber

A high-resolution technique is described which allows the relative wavelength of individual laser spikes to be determined. The experimental setup consists of an Er-YAG laser source operating in the long pulse mode, a gas absorption cell with reference and cell output detectors, a Fabry-Perot etalon and detector for identifying the laser spike wavelength, a 5-m spectrometer for identifying wavelength region, and a data acquisition system. The resolving power of the measuring system is highly dependent on the resolution and stability of the etalon as well as on system SNR. The technique described is found to be capable of a spectral resolution comparable with that obtained from the largest grating and Fourier transform spectrometers and dye laser systems, but it is less than the resolution of diode lasers.