Difference-frequency generation in PPLN at 4.25 μm: an analysis of sensitivity limits for DFG spectrometers

Self-, Nitrogen-, and Oxygen-Broadening Coefficient Measurements in the ν1 Band of H2O Using a Difference Frequency Generation Spectrometer at 3 μm

“…Under these conditions the idler power was about 160 nW with a conversion efficiency of 0.01%/(W · cm). This value is in agreement with other results obtained for a pump wavelength at 0.860 µm (25) and at 0.850 µm (26). The infrared beam emerging from the crystal was collimated by a CaF 2 lens with focal length 100 mm.…”

A continuous-wave difference-frequency generation laser operating in the mid-infrared (3–5μm) region for accurate line intensity measurements

“…3). The measured conversion efficiency of the instrument around 4 lm is 0.0082 W À1 m À1 , which is much higher than the theoretical value (0.0025 W À1 m À1 ) for perfect phase matching in bulk crystals [26,31,[39][40][41] using the numbers given above. Another calculation, taking also into account the effects of the inverted periodic crystal structure and of the QPM process, shows that we obtain up to 60% of the theoretical conversion efficiency value [26].…”

“…Only recently, several groups have started to develop new compact cw infrared lasers based on DFG generation in periodically poled lithium niobate (PPLN) using allsolid-state pumping lasers operating at room temperature in the near-infrared [30][31][32][33]. These cw DFG lasers do present several advantages compared to other infrared laser sources (small size, operation at room temperature, broad tuning range of several 100 cm À1 .…”

“…While the instrument design is very similar to the lasers developed in other groups [30][31][32][33], we have focused this study on the characterization of the laser, in particular for the measurement of molecular line intensities. It will be demonstrated that the DFG laser, which is tuneable in the 3-5 lm range, has a very high spectral resolution (about 1 MHz).…”

Spatial Mode Control of Radiation Generated by Frequency Difference in Periodically Poled Crystals

“…For spectroscopic applications, wide tunability, narrowlinewidth, low-noise, and mode-hop-free operation are more important than high power and can be obtained using DFG [3]. Sub-Doppler molecular lines using a DFG-based spectrometer have been recently observed in our group, at a power as low as 10 mW [4].…”