Measurement of the phase fluctuations in a He–Ne Zeeman laser

Abstract

The measurement of the phase fluctuations caused by spontaneous emission in the oscillation of a He–Ne laser operating at 1.15 μ is reported. The frequency fluctuations in the signal resulting from heterodyning two independent modes in the laser were measured as f 2(ν) =(9.6±2)×10−2 Hz2/Hz for 1.65×107 stored photons per mode and f 2(ν) =(2.7±0.3)×10−1 Hz2/Hz for 6.2×106 stored photons per mode. These values are to be compared with the theoretical minima for these cases, which are calculated to be f 2(ν) =5.1×10−2 Hz2/Hz and f 2(ν) =1.4×10−1 Hz2/Hz, respectively.