Electro optic dual comb spectroscopy for mid-infrared applications

ELECTROCOMB项目的目标是在中红外光谱区域产生波长灵活的频率梳，作为分子光谱和分析的双梳光谱(DC)的强大工具。频率梳，特别是用于光谱应用的双梳方案目前正经历着强劲的发展。正在开发新的梳子生成方案，以满足光谱和分析应用在波长区域、光谱覆盖、测量速度和灵敏度方面的特殊需求。ELECTROCOMB项目建立在利用连续波(CW)激光器的电光调制(EOM)产生梳子的概念上，该概念是专门为双梳子应用而开发的。用同一主连续波激光器产生两个梳子，有助于大大减少两个梳子相互同步所需的工作量。此外，它还允许根据要分析的光谱特征的宽度调整重复率(梳线间距)。另一方面，与其他来源相比，该方案目前在频谱梳宽方面的效率较低，而且该概念仅限于电信范围，主要是由于技术原因而在1.5μm左右。ELECTROCOB旨在克服这些障碍。该项目将提高对基于电光的梳子的基本理解，以增加光谱展宽，并将噪声水平降低到接近基本极限。这将与使用CHI(2)和CHI(3)过程的非线性光学频率转换到中红外(MID-IR)范围(3-5μm)的新颖和有效的方法相结合。这将使我们能够使用这种类型的分布式控制系统在痕量气体分析中具有挑战性的应用，这些应用确实需要高灵敏度和广泛的光谱覆盖。该项目联合体结合了ICB实验室(法国勃艮第大学)在用于梳子产生的光纤和集成波导中的非线性过程方面的互补专业知识，以及IMTEK小组(弗莱堡大学)关于通过二次非线性进行频率转换、数据采集和气体分析的专业知识，以达到对梳子产生及其在气体光谱学中的有效应用的基本理解的新水平。此外，联合项目将使合作伙伴能够使用各自合作伙伴实验室中的高度专业化设备，这将大大提高研究工作的效率。因此，我们期待着我们的联合ELECTROCOMB项目将对致力于研究和使用频率梳源用于光谱应用的学术和工业社区产生重大影响。这将通过在主要国际期刊上发表我们的成果以及在有声望的国际会议上发表演讲来实现。

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.