Knowledge Bank

We have observed the sub-Doppler saturation spectrum of the $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C16O2$ near 4.3 $\mu m$ using a mW-level DFG (Difference Frequency Generation) source. The DFG radiation is generated by a 1-W Ti:sapphire laser and a Nd:YAG laser amplified by 10-W fiber amplifier in a 50-mm long PPLN (Periodically Poled Lithium Niobate) crystal. We are able to generate 2 mW DFG power at 4.3 $\mu m$. The Nd:YAG laser is frequency-doubled, and frequency stabilized on one $\mathrm{<mrow\; data-mjx-texclass="ORD">127</mrow>}I2$ hyperfine transition. The Ti:sapphire laser is locked onto the center of $\mathrm{CO}2$ transition and its frequency is measured by an OFC (Optical Frequency Comb). In this talk, we will report our recent measurements on the high J 0001 $\to$ 0000 fundamental band transitions and the hot band 0111 $\to$ 0110 transitions. To increase the signal-to-noise ratio of the observed spectra, the $\mathrm{CO}2$ absorption cell in heated to a temperature $>500\mathrm{irc}C$.