Mid-Infrared Precision Frequency Combs

We propose a new concept for generation of ultra-broadband frequency combs in the mid-infrared frequency range. An octave-wide mid-infrared frequency comb output will produced by a sub-harmonic optical parametric oscillator pumped by a compact femtosecond fiber laser. Such a broadband frequency comb source will permit precision spectral measurements in the wavelength region of strong molecular absorption bands, based on the recently developed principle of coherent Fourier-transform infrared spectrometry. Spectroscopic detection method based in our new source will offer an unprecedented speed of acquisition of spectral information, high accuracy and sensitivity and might be used for detection of chemical and biological agents, explosives'' vapors, as well as for medical breath analysis. BENEFIT: Our objective is to develop a radically new source of coherent octave-wide mid-infrared frequency combs and demonstrate precision spectral measurements in the wavelength region of strong molecular absorption bands. The frequency combs source will be based on a sub-harmonic optical parametric oscillator pumped by a compact mode-locked 1550 nm femtosecond fiber laser and will operate in the mid-IR range of 2.5-5 microns where main molecular signatures for most atmospheric organics, volatiles, and isotopes are found.  For precision spectral measurements, we will apply a recently developed principle of coherent frequency-comb Fourier-transform infrared spectrometer (CFC-FTIR) which will allow massively parallel spectroscopic probing in the mid-infrared region. This will result in an unprecedented speed of data acquisition (1000 spectra/sec), high spectral resolution (0.05 cm-1), and high detection sensitivity at parts-per-trillion level.  The proposed device can perform ultrasensitive molecular identification and can be used for detection of trace chemical and biological agents, explosives'' vapors, as well as for detection of biomarkers in the exhaled breath for the medical breath analysis. The sensors broad-band range will allow the detection of a large number of different molecular simultaneously.  )