LOW-FREQUENCY NOISE OPTICALLY PUMPED FIR LASER WITH FREQUENCY STABILIZED PUMP

A new method of frequency stabilization of the pumping laser of an opt ically pumped far infrared laser (OPFIRL) has been developed. With the frequency of the pump stabilized in this way the phase noise of the O PFIRL is minimized and the laser can remain phase locked to a hydrogen maser for several hours. A measurement of the spectral density of pha se noise of the generated submillimetric radiation at 716 GHz is repor ted; to our knowledge this is the first time that a measurement of pha se noise, using a mixer as phase discriminator, is performed in the su bmillimetric domain. (C) 1997 Elsevier Science B.V.