Ultralong Faraday laser as an optical frequency standard

Abstract

In this letter, we introduce the concept and experimentally demonstrate an ultralong Faraday laser as an optical frequency standard in principle. The ultralong Faraday laser is based on the Faraday anomalous dispersion optical filter (FADOF) with ultra-narrow bandwidth and the ultralong fiber extended cavity of $800$ m. The ultra-narrow FADOF is based on atomic transition line of isotope ${}^{87}$Rb, which has an ultra-narrow bandwidth of $26.0$ MHz and a transmission of $23.6\%$ at $780$ nm. Fibers of length $150$ m and $800$ m are used as ultralong fiber extended cavities, which provide optical feedback and give extremely small FSR of $0.667$ MHz and $0.125$ MHz, respectively. The mechanism of the proposed ultralong Faraday laser is to combine FADOF's ultra-narrow bandwidth and ultralong cavity's small free spectral range to limit the lasing frequency within FADOF bandwidth covered by the semiconductor gain. The active lasing frequency of the ultralong Faraday laser is determined by the center frequency of FADOF transmission, which is corresponding to atomic transition $5^2{S}_{1/2},F=2\to 5^2{P}_{3/2},F^{\prime }=2,3$ of isotope ${}^{87}$Rb. The Allan deviation of the fractional frequency of the ultralong Faraday laser output signal in 0.1 s -- 1 s measuring time is around $1\times 10^{-11}$.

arXiv commentCorrected the calculation method of the result of Allan deviation of fractional frequency

References in corpus (6)

• An Optical Lattice Clock with Accuracy and Stability at the $10^{-18}$ Level
• An atomic clock with $10^{-18}$ instability
• Making optical atomic clocks more stable with $10^{-16}$ level laser stabilization
• Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre
• Steady-state, cavity-less, multimode superradiance in a cold vapor
• Controllable optical phase shift over one radian from a single isolated atom