Asynchronous Mid-IR optical parametric oscillator frequency combs

In a dual-comb spectrometer, two asynchronous laser frequency combs with different pulse repetition rates and stabilized carrier-envelope-offset (CEO) frequencies (f_CEO) are required [1]. For trace-gas detection, it is essential to extend coverage to the 2.5 - 20 μm mid-infrared (mid-IR) region. Recently we introduced a method for generating two separate mid-IR pulse sequences with slightly different repetition rates from a single SPOPO [2]. Here, we report the detection and stabilization of the CEO frequencies of the two asynchronous channels simultaneously.