Abstract
This paper presents an external-cavity dual-wavelength mid-infrared multiple optical parametric oscillator based on a single MgO:APLN crystal, which is pumped by a pulsed 1.064 μm laser. The output power and beam qualities of parametric lasers at different repetition rates and transmittance were studied. When the pump power of the 1.064 μm laser was 34.5 W, the repetition rate was 63 kHz, the maximum output powers of 2.79 W@3.30 μm and 4.92 W@3.84 μm were obtained with the transmittance T = 60%@1.57 μm, corresponding to optical–optical conversion efficiencies of 8.1% and 14.3%, respectively. Meanwhile, the beam qualities of two mid-infrared laser beams were effectively optimized and the pulse widths of 9.72 ns@3.30 μm and 9.67 ns@3.84 μm were obtained synchronously.
Highlights
The dual-wavelength lasers in the range of 3~5 μm have versatile applications such as military confrontation and laser radar [1,2]
An optical isolator and a half-wave plate(HWP) were used to isolate the 1.064 μm laser returning to the pump source, and the laser was focused into the MgO:APLN crystal by a convex lens with a focal length of 150 mm
With the continuous increase in repetition rate, the power of the 3.84 μm mid-infrared laser decreased gradually, and the gain competition of two parameter outputs in the cavity became more and more intense; for the 3.3 μm laser, the change in repetition rate had a gentle effect on its output power
Summary
The dual-wavelength lasers in the range of 3~5 μm have versatile applications such as military confrontation and laser radar [1,2]. A multiple optical parametric oscillator (MOPO) is an effective way to obtain a multi-wavelength tunable laser in the same spectral region [3,4,5,6,7]. Due to the multiple frequencies and complex energy conversion path in the process of synchronous oscillation, which produces the gain competition of the multiple parametric outputs this can result in power distribution imbalance, beam quality deterioration, spectrum broadening, and so on [8,9,10,11,12,13,14]. In 2020, the college of Advanced Interdisciplinary Studies from National University of Defense Technology used a traditional Raman fiber oscillator as a dual-wavelength pump source, the output power of 2 W@3.27 μm and 4.98 W@3.66 μm were achieved [17,18]
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