Narrow linewidth high beam quality long pulse solid-state yellow laser at 589 nm by intra-cavity sum-frequency generation

We demonstrate a compact narrow linewidth high beam quality diode pumped solid-state microsecond (mu s) pulse yellow laser at 589 nm by intra-cavity sum-frequency generation (SFG). The resonators are based on a symmetrical co-folding-arm plane-plane structure with a two-rod configuration for birefringence compensation, working in a thermally near-unstable range of the cavity. A twisted-mode cavity for spatial hole-burning elimination and an etalon in 1319 and 1064 nm resonators are employed to realize the narrow linewidth laser output. Moreover, in order to improve the SFG efficiency, the laser spiking due to relaxation oscillations is suppressed by inserting frequency doublers in both 1319 and 1064 nm oscillators. By carefully designing the cavity, a 4.8 W quasi-continuous wave yellow laser source at 589 nm is generated with a beam quality factor of M-2 = 1.63 and a linewidth of similar to 0.44 pm. The 589 nm laser is operated at a repetition rate of 500 Hz with pulse duration of similar to 115 mu s.