Frequency stabilized distributed feedback laser diode system at 1.323 μm using the modulated Zeeman effect

We present the design of a highly stable, compact system that achieves the frequency stabilization of a distributed feedback laser diode to an excited-state argon transition at 1.323 μm. The argon atomic reference is generated in a miniature hollow cathode lamp. A small a/c magnetic field is used to Zeeman split the transition and both right- and left-circularly polarized light are used to generate the error discriminant signal and cancel laser relative intensity noise. The output does not contain any frequency modulated components and has been measured to have long-term frequency stability of better than 8×10−11 (20 kHz) with the Allan Variance technique.