Dual-frequency comb generation with differing GHz repetition rates by parallel Fabry–Perot cavity filtering of a single broadband frequency comb source

Abstract

We present a dual-comb-generator based on a coupled Fabry-Perot filtering cavity doublet and a single seed laser source. By filtering a commercial erbium-doped fiber-based optical frequency comb with CEO-stabilisation and 250 MHz repetition rate, two broadband coherent combs of different repetition rates in the GHz range are generated. The filtering doublet consists of two Fabry-Perot cavities with a tunable spacing and Pound-Drever-Hall stabilisation scheme. As a prerequisite for the development of such a filtering unit, we present a method to determine the actual free spectral range and transmission bandwidth of a Fabry-Perot cavity in situ. The transmitted beat signal of two diode lasers is measured as a function of their tunable frequency difference. Finally, the filtering performance and resulting beat signals of the heterodyned combs are discussed as well as the optimisation measures of the whole system.

Comb mode filtering silver mirror cavity for spectroscopic distance measurement

“…The combination with a compact non-moving spectrometer would be very useful for field and industrial applications. In this paper, we report the development of an external filter cavity 19,21,22 which increases the mode spacing of the fiber based combs such that a VIPA spectrometer can resolve them for applications in long distance measurement. The cavity has been used to increase the mode spacing of an Er-doped fiber based frequency comb with a repetition rate of 100 MHz to 1 GHz, well beyond the resolution limit, 680 MHz, of the VIPA spectrometer.…”

Technological advances in measurements and intelligent instrumentation

“…Simultaneous multiple degrees of freedom (DoF) measurement is realized by developing highly accurate interferometric system based on a modified homodyne Twyman-Green interferometer concept. Wang et al [1] also developed on-machine error identification and compensation methods for micro machine tools while Mildner et al [2] successfully advanced a dual-frequency comb generation with differing GHz repetition rates by parallel Fabry-Perot cavity filtering of a single broadband frequency comb source. Meanwhile, Lu et al [3] proposed a two-degree-of-freedom (2-DOF) displacement measurement system based on double diffraction gratings for precise displacement measurement.…”

“…For theoretical measurement simulation, Juang and Chen [4] conducted 3D finite element simulations on conductive multilayer films to study the relationship between the reading of the four-point probe and the conductivity of the individual layers. The resistivity of each layer sequentially can be determined with the original correction factor π/ln (2), after deposition of each layer.…”