Frequency control of a Nd(3+) glass laser

It is found that laser emission can be obtained in narrow lines less than 0.1 A wide anywhere within a 130-A interval centered about the peak emission at 1.06 mu by the use of thin reflecting plates acting as wavelength-sensitive mode selectors. For a plate aligned perpendicular to the axis of the laser the emission is at those wavelengths at which the plate thickness is an odd number of quarter wavelengths. The plate tends to produce a spiking emission as a function of time and no loss in output energy.