Radiofrequency synthesiser with an intrinsic instability of 5 × 10−15 at the averaging time of 1 s based on a femtosecond erbium-doped fibre laser

• Published in: Quantum electronics (Woodbury, N.Y.) N.Y.), 2020-12, Vol.50 (12), p.1155-1159
• Main Authors: Kireev, A.N., Shelkovnikov, A.S., Tausenev, A.V., Tyurikov, D.A., Gubin, M.A.
• Format: Article
• Language: English
• Subjects: Doped fibers; Erbium; Femtosecond pulses; femtosecond synthesiser; Fiber lasers; fibre laser; Frequency ranges; frequency standard; Frequency standards; He - Ne/CH; Lasers; Optical frequency; Radio frequency; Synthesizers; ultra-low phase noise microwave generator
• ISSN: 1063-7818; 1468-4799
• DOI: 10.1070/QEL17437

A radio-optical synthesiser intended for operation in a radio-frequency master oscillator with an optical He - Ne/CH4 frequency standard (λ = 3.39 μm) is developed on the basis of a femtosecond erbium-doped fibre laser. The synthesiser generates equidistant harmonics in the frequency range of 1 - 10 GHz with stability determined by the optical frequency standard. A stable supercontinuum spectrum is formed in the range around 1.06 μm, which provides stable 24-hour operation of the synthesiser and is important for practical applications in off-laboratory conditions. A direct comparison of the output frequencies of two synthesisers shows that the up-grade of the fibre laser and detection system of femtosecond pulses results in the synthesiser intrinsic instability of 5 × 10−15 at the averaging time of 1 s. Such a value is by an order of magnitude less than that obtained in our earlier works.