Circuits for optical frequency stabilization of metrological lasers

Nowadays, the Slovak National Length Standard is based on the HeNe laser. Its optical frequency is stabilized by the saturated absorption method in I-127(2) iodine molecules with relative uncertainty 10(-11). This solution is dominant in majority of metrological institutes of. the world so far [1]. The ground of long time laser stability is in its thermally stable mechanical construction. Optoelectronic feedback allows stabilizing the laser frequency precisely at wavelength causing the saturated absorption in iodine vapour. This feedback is controlled by signal of photodiode and action control element is the piezo carrying the laser mirror. The operation principle and the arrangement of diode laser differ from that of HeNe laser and therefore the application of method mentioned above must be adapted to new conditions. This contribution is aimed for design of electronic circuits providing for this new approach.