Broadband, high-power, continuous-wave, mid-infrared source using extended phase-matching bandwidth in MgO:PPLN

Abstract

We report a compact and viable source of broadband, high-power, cw, mid-IR radiation based on a singly resonant optical parametric oscillator (SRO) pumped by a wide-bandwidth cw Yb fiber laser centered at 1060 nm. By exploiting the extended phase-matching bandwidth in a 50 mm crystal of MgO:PPLN and a ring SRO cavity, we obtain 5.3 W of broadband idler output for 25.5 W of pump at >80% depletion, transferring a pump bandwidth of 73.9 cm(-1) to an idler spectrum spread across an equal bandwidth centered at 3454 nm. By deploying output coupling of the signal, we generate 11.2 W of total power at 44% extraction efficiency with a pump depletion of >73% at the maximum available pump power. Measurements of transverse modal power confirm Gaussian distribution of signal and idler beams.

Parametric Spectral Properties of Optical Parametric Amplification Based on Broadband Pump

“…When parametric central wavelength is 3.487 m, the parametric spectral BW is 90.5 nm (Fig.3), which is about 80 nm observed from Fig.4. Fig.4 shows good accordance with the experimental results published [6]. …”

“…When parametric central wavelength is 1.523 m, the parametric spectral BW is about 1.2 nm (Fig.3) calculated with Eq. (6), which is about 1.1 nm in Fig.4. It successfully explains the narrow linewidth of parametric wavelength 1.523 m in published experimental results [6].…”

“…(6), which is about 1.1 nm in Fig.4. It successfully explains the narrow linewidth of parametric wavelength 1.523 m in published experimental results [6]. When parametric central wavelength is 3.487 m, the parametric spectral BW is 90.5 nm (Fig.3), which is about 80 nm observed from Fig.4.…”

“…Generally, broadband mid-IR is produced by means of three-wave nonlinear interactions such as OPA and OPO [4,5]. For instance, recently Ritwick Das et al demonstrated from their experiments a broadband high-power cw mid-IR source by exploiting a broadband CW Yb fiber laser pump [6].…”

Tm:YLF laser-pumped periodically poled MgO-doped congruent LiNbO_3 crystal optical parametric oscillators

“…Quasi-phase matching OPO combines the advantages of collinear propagation of the pump and the generated waves with no walk-off in space, large acceptance angle, and possibility of using the largest nonlinear optical tensor element. Through this method, substantial studies have been implemented to achieve laser in the mid-IR region based on a singly resonant OPO (SRO) constructed with periodically poled lithium niobate (PPLN) pumped by 1 μm lasers [4,5]. However, the conversion efficiency was confined, not exceeding the quantum limit set by the Manley-Rowe relations.…”