Numerical and theoretical work effectively assess the feasibility of the DCS method in the UV range. We propose to extend the already existing dual comb spectroscopy (DCS) methodology instrument from the IR to the near UV region to take advantage of the strong absorption cross-section of OH at 308 nm. To improve the understanding of the role of OH in the atmosphere, there is a need for instruments that should be sensitive, accurate, and have a fast acquisition time in the timeframe of the OH lifetime (ms). The radical OH interactions in the atmosphere remain not fully understood, as it is very challenging to measure. In this context, the radical OH has been recognized as one of the key molecule in the atmosphere, participating for instance to 90 % of the atmospheric methane loss. The atmospheric gas phase evolution is of main concern for air quality and climate evolution, as indicated in the recent IPPC Report.

Finally, the majority of the Ti:S noise seems to originate from the laser itself, which partly can be explained by the effect of relaxation oscillation frequency. The Ti:S is shown to have a cut-off frequency around 500 kHz, which means that noise structures of the pump laser above this frequency are strongly suppressed.

In particular, the cascaded system is seen to exhibit higher RIN than a setup with only a single nonlinear crystal. The frequency doubled light is shown to have a higher RIN than the fundamental light. It is demonstrated that improving the electrical noise provides an easy method for reducing the relative intensity noise (RIN) in all stages. Noise features originating from the electric power supply are evident throughout the whole transfer chain. This investigation includes electrical noise characterizations of the utilized power supplies, the optical noise of the fundamental light, the second harmonic light, and finally the optical noise of the femtosecond pulses emitted by the Ti:S laser.

This system consists of a DBR tapered diode laser, which is frequency doubled in two cascaded nonlinear crystals and used to pump the Ti:S laser oscillator. In this paper, we investigate the noise performance and transfer in a titanium sapphire (Ti:S) laser system.

Inpho 5.6 application master