Methane based microwave reference oscillator

Two microwave reference oscillators based on a He-Ne/CH
₄
optical frequency standard (λ = 3.39 μm) and femtosecond Er fiber laser (λ = 1.55 μm) optical-to-microwave frequency divider were created. The measurements have demonstrated short term frequency instability (Allan deviation) of the output microwave signal at 1.5 GHz at the level of 1×10
^-14
(τ = 1 s). Interrogative oscillator with such stability is attractive for application in Cs and Rb atomic fountains.