Electro optic dual comb spectroscopy for mid-infrared applications

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The ELECTROCOMB project aims at the generation of wavelength flexible frequency combs in the mid-infrared spectral region as a powerful tool for dual-comb spectroscopy (DCS) for molecular spectroscopy and analytics. Frequency combs and in particular dualcomb schemes for spectroscopic applications are currently experiencing a strong development. Novel comb generation schemes are being developed in order to address the specific needs of spectroscopic and analytical applications in terms of wavelength region, spectral coverage, speed and sensitivity of the measurement. The ELECTROCOMB project builds upon the concept of comb generation with electrooptic modulation (EOM) of a continuous-wave (cw) laser, which has been specifically developed with dual-comb applications in mind. Generating two combs from the same primary cw laser helps to drastically reduce the effort needed for the mutual synchronization of the two combs. In addition, it allows one to adjust the repetition rate (comb line spacing) according to the widths of the spectral features to be analyzed. On the other hand, the scheme is currently less efficient in terms of spectral comb width compared to other sources, and the concept is limited to the telecom ranges, mainly around 1.5 μm for technical reasons. ELECTROCOB aims at overcoming these handicaps. The project will improve the fundamental understanding of the electro-optic based comb in order to increase the spectral broadening and to reduce the noise level closer to the fundamental limits. This will be combined with novel and efficient approaches for the nonlinear-optical frequency conversion into the mid-infrared (mid-IR) range (3 – 5 μm) using both chi(2) and chi(3) processes. This will allow us to use this type of DCS for challenging applications in trace gas analysis which do require both high sensitivity and broad spectral coverage. The project consortium combines the complementary expertise of the ICB laboratory (Université de Bourgogne) on nonlinear processes in fibers and integrated waveguides for comb generation and of the IMTEK group (Freiburg University) on the frequency conversion via quadratic nonlinearities, data acquisition and gas analysis in order to reach a new level in fundamental understanding of comb generation and its efficient application in gas spectroscopy. In addition, the joint project will grant the partners access to highly specialized equipment in the labs of the respective partners which will greatly enhance the efficiency of the research work. As a consequence, we are expecting that our joint ELECTROCOMB project will have a strong impact on the academic and industrial communities working on and using frequency comb sources for spectroscopic applications. This will be achieved through the publication of our results in leading international journals and presentations in prestigious international conferences.