不同光斑遮挡度对6结GaAs激光能量转换芯片性能的影响

激光在空间进行实际传输的过程中存在不同障碍物遮蔽的情形,这将影响激光无线能量系统的输出特性,探究遮蔽度对光电转换效率所产生的影响则非常重要。通过6结等效二极管模型的理论模拟和实验研究了遮蔽度对6结激光能量转换芯片的性能影响。实验采用808 nm波长激光器作为光源,针对五种功率下的4种遮蔽度情景,对6结GaAs激光能量转换芯片的I-V曲线进行了实验测量,得到了光电转换效率与遮蔽度的关系。实验结果表明,光功率相同时,随着遮蔽度增加,6结激光能量转换芯片的短路电流、转换效率、开路电压减少。理论结果和实验结果一致。同时研究了存在遮蔽时,通过优化电路给出一种有效获得更高功率的优化策略。理论上分析了优化后电路相对于串联电路可获得更高的最大功率点,并且通过实验验证理论模拟的正确性。     

准相位匹配PPMgLN光参量振荡技术

 理论上分析了PPMgLN光参量振荡波长调谐特性，计算了泵浦阈值和转换效率。准相位匹配情况下，周期调谐是获得中红外波长调谐有效方法之一。采用高斯光束泵浦，当泵浦功率密度超过阈值泵浦功率密度约6.5倍时，可以获得最高转换效率，约71%。采用1 064 nm激光泵浦多周期PPMgLN晶体，实验上获得了波长调谐范围2.7~4.8 mm，当泵浦功率为8 W时，在波长3.7 mm处激光输出功率超过1.6 W，斜效率超过20%，相应的转换效率约为69%，与理论分析基本一致。     

双波长Yb∶YAG连续激光理论及实验研究

报道了Yb∶YAG双波长激光振荡阈值的理论结果,实验获得了连续双波长激光输出.实验中,采用紧凑的平凹腔结构、940nm光纤耦合LD端面泵浦方式,Yb∶YAG晶体作为激光晶体,采用10%、15%和20%的输出耦合镜,分别实现了单波长和双波长激光输出,在最高泵浦功率为20 W时,输出耦合率分别为10%、20%,最高获得3.94W的1 050nm激光和3.40 W的1 030nm激光,对应的光光转换效率分别为19.7%和17.0%;当输出耦合率为15%、泵浦功率为11.7 W时,获得0.79 W的双波长激光,对应的光光转换效率为6.8%,功率比为1∶1.3,通过光栅光谱仪测量得到双波长谱线中心分别为1 030.31nm和1 047.50nm;当1 030nm激光功率为3.0 W时,30min内输出功率RMS稳定性优于0.18%.该实验结果与理论分析相吻合,可应用于设计稳定可靠的掺Yb双波长激光器.     

LD泵浦Nd:YVO_4双波长运转腔内和频491nm激光器

分析了Nd:YVO4激光器实现双波长运转及腔内和频的条件,利用一种LD泵浦Nd:YVO4晶体产生1 064 nm和914 nm双波长激光束,采用一个线性平凹腔结构,利用腔内Ⅰ类临界相位匹配LBO和频,获得了连续波输出的全固态激光器。实验采用端面结构,在5.0 W的808 nm泵浦功率下,获得了最高功率为2.5 mW连续波TEM00的激光输出,光-光转换效率为0.05%。     

基于石墨烯的1 064 nm连续锁模超短脉冲激光器

介绍了利用沉积在增透镜上的石墨烯薄膜作为可饱和吸收体、808 nm激光二极管端面泵浦Nd∶YVO4晶体的1 064 nm连续锁模激光输出特性。采用W型折叠谐振腔结构,在808 nm泵浦功率为8.0 W时,有稳定的连续锁模脉冲输出,平均输出功率达到185 mW;当抽运功率增加到16.0 W时,获得了中心波长1 063.4 nm、脉冲宽度为518 fs、重复频率为66.7 MHz、最大平均输出功率为323 mW的百飞秒量级超短脉冲激光输出。实验结果表明:石墨烯具有优良的可饱和吸收性,在1 064 nm波段能够实现高功率、百飞秒量级连续锁模脉冲激光输出。     

高效率内腔式2 μm简并光学参量振荡器

报道了一种高效率的2 μm光学参量振荡器. 利用1.064 μm声光调Q Nd:YVO₄激光器抽运基于氧化镁掺杂周期性极化铌酸锂的内腔式光学参量振荡器, 在简并状态实现了稳定高效的2 μm激光输出. 当808 nm激光二极管抽运功率为20 W, Q开关工作频率为15 kHz时, 产生了平均功率为3.5 W、脉冲宽度为1.4 ns的2 μm激光, 光-光转换效率为17.5%, 斜效率为25%. 据我们所知, 该转换效率在2 μm波段内腔式光学参量振荡器中是最高的.     

基于石墨烯的1064nm连续锁模超短脉冲激光器

介绍了利用沉积在增透镜上的石墨烯薄膜作为可饱和吸收体、808 nm激光二极管端面泵浦Nd∶YVO4晶体的1 064 nm连续锁模激光输出特性。采用W型折叠谐振腔结构,在808 nm泵浦功率为80 W时,有稳定的连续锁模脉冲输出,平均输出功率达到185 mW;当抽运功率增加到160 W时,获得了中心波长1 0634 nm、脉冲宽度为518 fs、重复频率为667 MHz、最大平均输出功率为323 mW的百飞秒量级超短脉冲激光输出。实验结果表明：石墨烯具有优良的可饱和吸收性,在1 064 nm波段能够实现高功率、百飞秒量级连续锁模脉冲激光输出。     

LD抽运Nd:YVO4/KTP复合腔和频黄光激光器

在LD抽运的三镜复合腔Nd:YVO4激光器中,采用Ⅱ类临界相位匹配的KTP晶体对1064 nm和1342 nm两种波长激光进行和频,获得593 nm黄光连续输出.理论上从速率方程出发,导出1064 nm激光谐振腔和1342 nm激光谐振腔腔长之间的关系以及两个腔的腔镜透过率之间的关系.实验中,当808 nm抽运光的功率为12 W时,和频输出的黄光功率为340 Mw.光-光转换效率为2.8%.结果表明,采用三镜复合腔结构进行腔内和频是实现593 nm黄光输出的一种有效方法.     

高功率MgO∶PPLN光参变振荡器

报道了一台高功率中红外激光器。通过理论计算,得到了光参量振荡器输出波长随MgO∶PPLN晶体温度变化的调谐曲线,分析了晶体热膨胀对输出波长的影响;通过声光调Q,Nd∶YAG激光器输出的1064 nm激光作为抽运光,抽运掺氧化镁的周期性极化铌酸锂晶体(MgO∶PPLN),利用光参量振荡(OPO)技术实现了1.75μm和中红外2.71μm激光输出。当重复频率为7 kHz,抽运光功率为104 W时,总的平均输出功率为53.2 W,转换效率为51%。从转换曲线上看,并没有达到饱和区域,因此在晶体损伤阈值以下,增加抽运光功率,OPO的输出功率将会有所提高。     

掺氢与激励电路对钡蒸气激光输出特性的影响

对用Blumlein电路放电激励的钡蒸气激光在掺氢和不掺氢时的输出特性进行了实验研究 .结果表明 ,用掺氢1 5 %的氖气作缓冲气体能使激光功率增加近 2倍 .在此基础上 ,进一步比较了相互作用电路与Blumlein电路时钡蒸气激光的输出特性 ,发现相互作用电路能显著提高钡蒸气激光的输出功率和效率 ,获得了 3W最大功率和 0 4 %效率的 1 5 μm波长激光输出 .测量并分析了各工作参量与激光功率之间的关系 ,定性解释了掺氢与相互作用电路的作用机理     

A compact and high efficiency diode pumped green laser based on MgO doped PPLN

In this work, an efficient intra-cavity second harmonic generation of green laser in a periodically poled MgO doped LiNbO₃ (MgO:PPLN) bulk crystal using a compact Nd:YVO₄ laser as a fundamental laser source is reported. Different length, different working temperature MgO:PPLN crystals are tested and investigated in the SHG experiments. The maximum output power at 532 nm is 6.2 W at the absorbed pump power at 808 nm of 14 W, the optical to optical conversion efficiencies from 808 to 532 nm and 1064 to 532 nm are 43 and 77%, respectively, the instability in 2 hours is less than 5%.     

Diode-pumped Nd:LGS/LBO laser at 452 nm

We report a blue laser at 452 nm generation by intracavity frequency doubling of a continuous wave (cw) laser operation of a 904 nm Nd:LGS laser under 808 nm diode pumping. A LiB₃O₅ (LBO) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation (SHG) of the laser. At an incident pump power of 17.8 W, as high as 1.14 W of cw output power at 452 nm is achieved. The optical-to-optical conversion efficiency is up to 6.4%, and the fluctuation of the blue output power was better than 4.1% in the given 30 min.     

High-power and high optical conversion efficiency diode-end-pumped laser with multi-segmented Nd:YAG/Nd:YVO_4

A novel flat-flat resonator consisting of two crystals(Nd:YAG + Nd:YVO_4) is established for power scaling in a diode-end-pumped solid-state laser. We systematically compare laser characteristics between multi-segmented(Nd:YAG + Nd:YVO_4) and conventional composite(Nd:YAG + Nd:YAG) crystals to demonstrate the feasibility of spectral line matching for output power scale-up in end-pumped lasers. A maximum continuous-wave output power of 79.2 W is reported at 1064 nm, with M_x~2= 4.82, M_y~2= 5.48, and a pumping power of 136 W in the multi-segmented crystals(Nd:YAG + Nd:YVO_4). Compared to conventional composite crystals(Nd:YAG + Nd:YAG), the optical-optical conversion efficiency of multi-segmented crystals(Nd:YAG + Nd:YVO4) from 808 nm to 1064 nm is enhanced from 30% to 58.8%,while the laser output sensitivity as affected by the diode-laser temperature is reduced from 55% to 9%.     

980 nm 垂直腔面发射激光器低欧姆接触电阻制备

研究了980 nm的垂直腔面发射激光器(VCSEL)欧姆接触技术.降低VCSEL的欧姆接触电阻,可有效地提高VCSEL的输出功率和延长其可靠性.P面采用高掺杂的P-GaAs/Ti/Pt/Au系统,N面采用N-GaAs/Ge/Au/Ni/Au系统,通过优化合金温度,得到了最佳优化合金温度为440 ℃,最低欧姆接触电阻值为0.04 Ω,同时对比了440 ℃和450 ℃器件的输出功率和转换效率之间的对比关系.测试结果表明,440 ℃器件的欧姆接触电阻0.04 Ω,峰值波长980.1 nm,光谱的半高宽0.8 nm,平行发散角θ_‖ 15.2°,垂直发散角θ_⊥ 13.5°,输出功率1.4 W,转换效率最大值为14.4%,而450℃的器件欧姆接触电阻为0.049 Ω,输出功率为1.3 W,转换效率为12.8%.通过优化合金温度能有效地降低980 nm的VCSEL欧姆接触电阻.     

555 nm laser sources based on intracavity frequency doubling of Nd:YGG laser

We report for the first time a yellow-green laser at 555 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1110 nm Nd-doped yttrium gallium garnet (Nd:YGG) laser under in-band diode pumping at 808 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 18.5 W, as high as 2.31 W of CW output power at 555 nm is achieved. The optical-to-optical conversion efficiency is up to 12.4%, and the fluctuation of the yellow-green output power was better than 2.8% in the given 4 h.     

912 nm laser operation in diode-pumped grown-together composite Nd:GdVO4/GdVO4 crystal

Novel grown-together Nd:GdVO₄/GdVO₄ composite crystals were presented for the first time, which would be longitudinally pumped by 808 nm diode-laser to efficiently operate on continuous-wave (CW) 912 nm laser at room temperature. The maximum output power of 8.15 W at 912 nm laser was obtained successfully at the absorbed pump power of 28.0 W, giving the corresponding optical-to-optical conversion efficiency of 29.1% and the average slope-efficiency of 44.2%. Comparative experimental results show that the laser performance was influenced significantly by the Nd³⁺-doped concentration of the crystals, which would be optimized according to its energy-transfer upconversion (ETU) spectrum.     

808 nm高占空比大功率半导体激光器阵列

 采用渐变折射率分别限制单量子阱宽波导结构,通过降低非辐射复合、有源层载流子泄露、散射和吸收损耗来提高出射效率和降低激光阈值电流,从而提高半导体激光器阵列的输出功率;同时使P面具有更高的粒子掺杂数密度,优化N面合金条件,降低半导体激光器的串联电阻,降低焦耳热,提高了半导体激光器阵列的转换效率。利用金属有机化学气相淀积技术生长GaInAsP/InGaP/AlGaAs渐变折射率分别限制单量子阱宽波导结构激光器材料,利用该材料制成半导体激光线阵列在20%高占空比的输入电流下,半导体激光器的输出峰值功率达到189.64 W(180 A),斜率效率为1.1 W/A,中心波长为805.0 nm,阈值电流为7.6 A,电光转换效率最高可达55.4%;在1%占空比的输入电流下,阵列的输出峰值功率可达324.9 W(300 A),斜率效率为1.11 W/A,阈值电流为7.8 A,电光转化效率最高达55.6%,中心波长为804.5 nm。     

808nm半导体激光芯片电光转换效率的温度特性机理研究

提高808 nm大功率半导体激光器电光转换效率具有重要的学术意义和商业价值,是实现器件小型化、轻量化、高可靠性的必要前提.本文以腔长1.5 mm的传导冷却封装808 nm半导体激光阵列为研究对象,在热沉温度-40—25?C范围内对其进行光电特性测试,对不同温度下电光转换效率的影响因子进行了实验研究和理论分析.结果表明:在-40?C环境温度下,最高电光转换效率从室温25?C时的56.7%提高至66.8%,内量子效率高达96.3%,载流子泄漏损耗的占比贡献由16.6%下降至3.1%.该研究对实现808 nm高效率半导体激光芯片的自主研发具有重要意义.     

Single-frequency 1.25 W monolithic lasers at 1123 nm

Experimental investigation ofd Nd:YAG monolithic nonplanar ring lasers operated at 1123 nm wavelength is presented. Stable single-frequency 1123 nm laser output has been obtained with successful suppression of the strong 1064 nm radiation. Single-frequency output power of 1.25 W is demonstrated with a pump power of 3.98 W at 808 nm, which gives a slope efficiency of 39%. The laser frequency tuning range is over 3 GHz, and the average tuning rate with temperature is -2.6 GHz/ degrees C. A strong iodine absorption line can be covered within the laser frequency tuning range.     

A Micro Blue-violet Laser by Frequency Doubling of Semiconductor Laser

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