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Absolute wavelength measurement of 633nm iodine stabilized He-Ne laser

Accurate iodine spectroscopy measurement plays important role in wavelength metrology, precise spectrum detection and interferometry measurement. In all the spectrum of iodine, the saturation absorption lines at 633 nm are the most widely used with the iodine stabilized He-Ne laser. Due to its weak output power, it is difficult to directly measure the absolute frequency with femtosecond frequency comb. In this paper, we present a new optical beating note system based on polarization maintaining fibers, which is employed to measure the weak iodine stabilized laser successfully. The experimental results show that a standard deviation of the frequency fluctuation of 12 kHz and a relative stability of 1.4×10-11 at 1 s are obtained, respectively. The reproducibility of the iodine stabilized laser is also studied, and a confident result of 3.8 kHz in peak to peak value is obtained with six months.