Frequency Doubling of a Pulsed Wavelength-Agile Erbium-Doped Fiber MOPA for Oxygen A-Band Spectroscopy

We report a pulsed wavelength-agile laser near 765 nm, which was frequency doubled from an erbium-doped fiber amplifier for oxygen A-band spectroscopy. A single frequency distributed feedback laser around 1529.6 nm was employed as the seed. After three stages of amplification, its average power was boosted to 610 mW and was then frequency doubled via a 15-mm-long MgO:PPLN crystal with the highest conversion efficiency of 34%. Thanks to the short crystal length expanding the acceptance bandwidth, a power difference of only 36% for the second harmonic output was achieved within the whole wavelength tuning range benefitting low-noise remote sensing. The measured oxygen transmission spectra using a 0.5-meter-long gas cell with multiple passes were mostly in good agreement with the calculations from HITRAN 2012 database indicating the capability of our laser for oxygen A-band related remote sensing.