A laser frequency comb is a broad spectrum composed of equidistant narrow lines. Initially
invented for frequency metrology, such combs enable new approaches to spectroscopy over …

The vast majority of gaseous chemical substances exhibit fundamental rovibrational
absorption bands in the mid-infrared spectral region (2.5–25 μm), and the absorption of light …

Dual-comb spectroscopy performed in the mid-infrared—where molecules have their
strongest rotovibrational absorption lines—offers the promise of high spectral resolution …

It was recently demonstrated that broadband quantum cascade lasers can operate as
frequency combs. As such, they operate under direct electrical pumping at both mid-infrared …

Mid-infrared (MIR) spectrometers are invaluable tools for molecular fingerprinting and hyper-
spectral imaging. Among the available spectroscopic approaches, GHz MIR dual-comb …

Nonlinear optical frequency conversion is one of the most versatile methods to generate
wavelength-tunable laser light in the mid-infrared region. This spectral region is particularly …

Recently, the field of optical frequency combs experienced a major development of new
sources. They are generally much smaller in size (on the scale of millimetres) and can …

Continuously pumped passive nonlinear cavities can be harnessed for the creation of novel
optical frequency combs. While most research has focused on third-order “Kerr” nonlinear …

Quantum cascade laser (QCL) frequency combs offer the potential for building ultra-compact
broadband spectrometers operating in the mid-infrared spectral region, where many light …

We experimentally demonstrate and theoretically explain the onset of optical frequency
combs in a simple cavity-enhanced second-harmonic-generation system, exploiting second …