High efficient and compact continuous-wave arrayed green laser is demonstrated based on periodically poled MgO:LiNbO3(PPMgLN), with a pump power of 16.5 W (5.5 W×3) at 808 nm, 7.36W output power of 3-arrayed green beams at 532 nm is achieved with a high optical-to-optical conversion efficiency of 44.6%.
High power green laser has many applications such as high brightness laser projection and large screen laser theater. A compact and high power green-light source has been developed in diode-pumped solid-state laser based on MgO doped periodically poled LiNbO3 (MgO:PPLN). 5W fiber coupled green laser is achieved by dual path Nd:YVO4/MgO:PPLN intra-cacity frequency-doubled. Single green laser maximum power 2.8W at 532nm is obtained by a 5.5W LD pumped, MgO:PPLN dimensions is 5mm(width)×1mm(thickness)×2mm(length), and the optical to optical conversion efficiency is 51%. The second LD series connected with the one LD, the second path green laser is obtained using the same method.
Then the second path light overlap with the first path by the reflection mirrors, then couple into the fiber with a focus mirror. Dual of LD, Nd:YVO4, MgO:PPLN are placed on the same heat sink using a TEC cooling, the operating temperature bandwidth is about 12°C and the stablity is 5% in 96h. A 50×50×17mm3 laser module which generated continuous-wave 5 W green light with high efficiency and width temperature range is demonstrated.
We have demonstrated a 1018 nm continuous wave fiber oscillator pumped by LDs operating at 976 nm. Three kinds of Ytterbium-doped dual-clad fibers, 15/130 μm fiber, 25/250 μm fiber and 30/250 μm fiber, are employed separately in the experiments. We achieve 67 W total output power with the 15/130 μm fiber for 100 W of pump power with a slope efficiency of 67%. And with the 25/250 μm fiber, 276 W total output power is generated for 372 W of pump power with a slope efficiency of 74%. In the end, 300 W output power with the slope efficiency of 81% is successfully achieved with the 30/250 μm fiber for 372 W of pump power. To the best of our knowledge, this is the highest output ever reached by a dual-clad fiber oscillator at this wavelength that ever reported in open detail.
The theory of laser cutter and the technology neck is analyzed. We can conclude that it is almost impossible to deal with the waste thick silicon wafers which are yielded in producing silicon wafers by conventional eroding or diamond cutting, while it is also unperfected with ecumenical laser cutter without good beam quality or precise laser and optics system. It is represented that high average power and high repetition rate laser with good beam quality and precise laser and optics system are pivotal to obtain excellent cutting effect such as thick groove depth, rapid cutting speed, fine kerf section without considering the effect of technique. Considering laser medium thermal lens effect and thermal focal length changing with pumping power, using plano-convex high reflectivity mirror as the back cavity mirror to compensate the heat lens influence, aλ/4 waveplate to compensate heat-induced birefraction, utilize the Nd:YAG self-aperture effect, more than 50 W average power 1.064 um IR output is obtained with beam quality factor (M2) equals 3.19. Through the LD-Pumped Nd:YAG laser cutter we developed with short focus length negative spherical aberration focusing lens, double axis linear step motor positioning system, suitable beam expander multiplying factor, appropriate diameter of exit beam aperture, proper repetition rate, when the cutting velocity equals 400mm/min, 0.75mm thick silicon wafer can be penetrated; when the cutting velocity equals 100mm/min, double-layer 0.75mm thick silicon wafer can be penetrated. The cross section is fine and the groove is narrow, the cutting quality meets the expecting demand.
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