Double-Peaked Mid-Infrared Generation Based on Intracavity Difference Frequency Generation

It was reported that a double-peaked mid-infrared laser was generated based on an intracavity difference frequency generation (DFG). The double-peaked pump source was achieved by suppressing the intensity at the central wavelength of the pump source. The double-peaked mid-infrared generation had a double-peaked spacing of 23–37 nm, and the full width at half-peak (FWHM) of the peaks was up to 30 nm. It was demonstrated that a tilted Bragg fiber grating (TFBG) with a specific transmission spectral depth and bandwidth can generate a double-peaked mid-infrared laser with controllable double-peaked spacing. It was the first generation of a double-peaked mid-infrared laser based on a near-infrared pumping spectral modulation. Furthermore, the double-peaked mid-infrared generation was tunable, and the FWHMs of the peaks were controllable by an intracavity DFG. It had a high potential for the monitoring and absorption of gas molecules by differential absorption lidar (DIAL).