What is the difference between single frequency and wavelength locked laser output?
The actual spectral position of a lasing SLM is defined by the frequency of the second cavity resonance at which the two cavities are locked. As the nature of this resonance is a constructive multiple beam interference, its spectral position is sensitive to the change of the optical path difference between the interfering beams due to thermal variation of this dimension in the relevant opto-mechanical components. At standard operational conditions when the lab temperature can vary easily by a few degrees Celsius, the laser cavity components are still kept at a fixed temperature with precision of around 0.10 Celsius. However, even such precise temperature control does not eliminate completely any drift of the spectral position of the lasing longitudinal mode. Depending on the laser emission wavelength, typically this drift is within a range from 1 to 2 pm (from 0.5 to 1.0 GHz). These values can be reduced to around 0.1GHz or lower if the environmental temperature, for instance, the temp
