Noise Reduction of the DC Excited He–Ne Laser Radiation by Application of Transversal HF Field

It is shown that the superimposition of transversal HF field on the tube of DC discharge excited He – Ne laser ($\lambda=0.63\ \mu\mathrm{m}$) can lead to the significant (25–35 db) reduction of noise level of laser radiation. The novelty is in deduction of the physical background of optimal frequency range at which the said noise reduction requires the minimal power of external HF field (not more than 2–3% of DC discharge input power). It is found that the optimal frequency of HF field should be close to the electron plasma frequency corresponding to the optimal (for lasing) electron density in the discharge plasma for its DC excitation (usually 1.5–2 GHz).