Measurement of Optical Frequency Stability by Using Spectral-Hole Burning

A method of measuring laser frequency stability is proposed by using the spectral-hole-burning technique. The power spectra of the measured laser can be recorded as a spectral hole, and the engraving time of the spectral hole is mapped into the frequency of the measured laser. Frequency fluctuation can be expressed by spectral hole frequency variation with different engraving times. By using the proposed method, the frequency stability of the external-cavity diode laser is measured to be 2.22×10^?9 with an integration time of 20 ms. The frequency stability measurement resolution reaches 14 kHz and the repetition rate is 50 Hz. Compared to the conventional method, it avoids the need for a high stability reference laser source.