Single Frequency Lasers
A single-frequency laser is a type of laser which operates within a singular resonator mode, achievable when the net gain bandwidth of the laser remains narrower than the frequency spacing of the resonator modes. In cases where the mode spacing isn’t adequately large to support a single resonator mode, single-frequency operation is maintained through the utilization of intracavity filters. This enables the single-frequency laser to possess an exceedingly narrow linewidth, frequently measuring only a few kHz, and an extended coherent length. A clear association exists between the coherence length and the spectral width of the laser.
