RESUMEN
A new method of harmonic beam coaxial combination (HBCC) from two intra-cavity frequency doubling branches was demonstrated. Firstly, two identical nanosecond (ns) 532â nm green lasers with high power and good beam quality were created. Each green laser was constructed of an intra-cavity frequency doubling branch based on a laser diode (LD) end-pumped acousto-optical (AO) Q-switched 1064â nm Nd:YVO4 laser in a LiB3O5 (LBO) nonlinear crystal. Each branch generated about 45â W green output at a 50â kHz pulse repetition rate (PRR) with diffraction limited beam quality. The first green beam was injected into the LBO crystal in the second branch, and the pulses from the two branches did not exist simultaneously. Then, the HBCC was performed. Consequently, an 83â W combined green output power at 532â nm was obtained with a combination efficiency of 92.2%. The PRR of the HBCC pulse was doubled to be 100â kHz, with a pulse width of about 22â ns, corresponding to a single pulse energy of 0.83â mJ and a peak power of 37.73â kW. The combined beam quality factor was measured to be M x2 = 1.80 in the x direction and M y2 = 1.71 in the y direction, respectively. Moreover, many more beams could also be combined with this method for further scaling the green power.
RESUMEN
An external-cavity dumped nanosecond (ns) ultra-broad-area laser diode (UBALD) at around 966â nm with high pulse energy is demonstrated. A 1â mm UBALD is used to produce high output power and high pulse energy. A Pockels cell (PC) combines with two polarization beam splitters (PBSs) and is employed to cavity-dump a UBALD operating at 10â kHz repetition rate. At a pump current of 23â A, 11.4â ns pulses with a maximum pulse energy of ≈1.9â µJ and a maximum peak power of ≈166â W are achieved. The beam quality factor is measured to be M x 2=19.5 in the slow axis direction and M y 2=2.17 in the fast axis direction. Moreover, maximum average output power stability is confirmed, with a power fluctuation of less than 0.8% rms over 60â min. To the best of our knowledge, this is the first high-energy external-cavity dumped demonstration from an UBALD.