基于精确延时控制的脉冲激光功率合成研究

介绍了脉冲固体激光器时域上的功率合成原理。为了实现多台脉冲固体激光器时域上的高精度功率合成,通过分析影响多台激光器之间时域上的同步合成效率的因素,采用了负反馈精确延时的控制方式对脉冲激光器出光时间进行精确控制。通过仿真和实验结果,验证了脉冲固体激光器功率合成方法的可行性,实现了三台激光器精度小于1ns的高精度激光功率合...     

连续/脉冲复合体制高功率固体激光技术研究

常规高功率激光器以连续或者长脉冲方式工作,与物质作用主要是依靠单一“加热”模式,针对其对复杂目标作用能力有限的问题, 提出一种连续和脉冲激光同时输出,脉宽、重频可调的新体制高功率激光技术,激光放大链路以特殊时域模式工作,即高重频脉冲与连续运转同时输出,在重频10 kHz时,实现输出功率4800 W,其中连续激光功率3600 W,脉冲激光功率1200 W,脉冲宽度为3.6 ns;在重频100 kHz时,实现输出功率4920 W,其中连续激光功率3100 W,脉冲激光功率1820 W,脉冲宽度为7 ns,光束质量4.8倍衍射极限 。     

激光二极管抽运Tm,Ho∶YLF晶体声光调Q激光器

对激光二极管端面抽运Tm,Ho∶YLF晶体声光调Q激光器的激光特性进行了研究。根据粒子跃迁和能量传递过程,在考虑能级传递上转换的前提下,建立了Tm,Ho∶YLF脉冲激光器的速率方程,得到了初始反转粒子数的解析表达式,分析了能量传递上转换效应对激光上能级反转粒子数的影响。在室温下实现了2 μm波长激光的脉冲输出。实验上给出并分析了Tm,Ho∶YLF脉冲激光器的平均输出功率、单脉冲能量和脉冲宽度随抽运功率以及声光Q开关调制频率的变化关系。在抽运功率为2.8 W,重复频率为9 kHz时,获得了平均输出功率为189 mW的激光脉冲,光光转换效率为6.8%。在重复频率为1 kHz时,得到最大单脉冲能量为65 μJ,峰值功率为0.17 kW。     

激光锁定F-P腔频率的有差锁定研究

基于有差伺服调节技术,实现了外置光学谐振腔的共振频率与钛宝石激光器工作频率的锁定.该技术采用压电陶瓷作为执行元件,通过对压电陶瓷的调制,实现了对透射激光功率的调制,并由锁相放大器解调获得伺服信号,该伺服信号经过高压放大器放大后控制压电陶瓷的伸缩来调控谐振腔的腔长,从而使腔的共振频率锁定在激光频率上.当激光上作于单一频毕时,谐振腔的谐振频率可以长时间地与激光频率保持锁定,锁定后腔的透射光功率相对起伏的稳定性为2%.当激光频率扫描时.谐振腔的谐振频率可以在2 GHz范围内不间断地与激光频率保持锁定.     

高平均功率固体激光及其大气传输

固体激光器是一种具有重要应用背景的高功率激光器,对包括激光波长、光束发射口径、发射功率、光束质量等在内的激光器参数的选择进行了分析,研究了大气介质的光学性质、激光大气传输效应以及激光辐射与靶目标的耦合机制与耦合效率等因素的影响.相关结果表明100 kW的固体激光器的综合效能可与2～3倍平均输出功率的DF化学激光器相当,这说明高平均功率固体激光器是一种具有潜在优势和良好发展前景的高功率激光器.     

Ho∶YAG激光泵浦的磷锗锌光参量振荡器

介绍了由Ho∶YAG声光调Q激光器输出2.1μm激光脉冲泵浦ZGP光参量振荡器。利用1.9μm激光器作为Ho∶YAG激光器的泵浦源,调Q重复频率为15kHz时,激光器输出功率21.5 W单一波长窄线宽激光。由Ho∶YAG激光器泵浦ZGP-OPO,最大输出中波红外激光8.85 W,激光脉冲宽度14.5ns,激光器输出斜效率高达80.9%。该激光器在气体检测及光电对抗等领域有广泛的应用前景。     

激光机器人焊接

许多读者将会亲眼见到用He-Ne激光器或类似气体激光器发出的细单色激光束描绘的图案(这种激光器的输出功率通常只有几个毫瓦).在制造工业中常常要求高得多的平均输出功率和运行效率.在电磁辐射谱近红外波段运行的电激励激光器可满足这种要求.这样的激光器有Nd:YAG(1μm)激光器,CO2(10μm)气体分子激光器和CO(5μm)激光器,这些激光器都发射高度定向的辐射束.虽然激光器的物理原理早在60年代就清楚了,但是把它们应用到工业加工的研究只是近来才迅速发展起来,特别是在德国和日本.“高科技”激光车间现已常规地应用了Nd:YAG和CO2激光器,…     

高功率脉冲染料激光放大器物理设计

从理论研究出发,用激光增益理论得到了在平衡状态下忽略染料分子激发态吸收时,高功率脉冲梁料激光放大器物理设计的简单方法,同时以铜蒸气激光器双侧抽运的平均输出功率52.5W的脉冲染料激光放大器为例,对其物理尺寸进行了模拟设计。     

脉冲CO2激光器注入锁定特性的数值模拟

扩展了脉冲CO2激光器的多频动力学理论。将多频动力学模型中的光强方程用光场方程代替,建立了脉冲CO2激光器注入锁定的理论计算模型。采用四阶经典龙格库塔(Runge-Kutta)算法,计算了不同注入信号强度和失谐频率下的激光输出功率、瞬时频率和增益系数。研究了注入锁定宽调谐横向激励大气压(TEA)CO2激光器模式锁定的稳定性问题。研究结果表明,当频率偏离谱线中心600 MHz时,为了实现稳定的模式锁定所需要的注入信号强度应比在谱线中心处高出两个数量级。理论结果和已发表的实验数据符合得很好。研究进一步预示:当激光器气压增大至10倍大气压时,对于同样调谐范围所需的注入信号强度仅比在谱线中心处高出10%左右。     

利用锁相环和TV-Rb钟控制飞秒激光脉冲的载波包络相移

为了实现对锁模飞秒钛宝石激光器的相位控制，采用改进的相移测量装置，使载波包络频移信号的信噪比提高到了40 dB以上.在此优化测量结果的基础上，利用电子锁相环技术，通过PZT改变激光器腔内端镜的倾斜将飞秒激光脉冲的载波包络相位锁定到了微波参考源TV-Rb钟10 MHz标准信号上，同时激光脉冲重复频率也采用另一个PZT控制激光腔长锁定到了同一个TV-Rb钟10 MHz信号上.锁定后的结果显示重复频率的锁定达到了TV-Rb钟本身的稳定度，而载波包络相位锁定后比锁定前稳定度提高了三个数量级.     

Linewidth narrowing and polarization control of erbium-doped fiber laser by self-injection locking

A novel and simple self-injection locking (SIL) configuration of distributed feedback (DFB) fiber laser is presented. By injecting the feedback light into the cavity of the fiber laser, it can realize that the line-width can be narrowed by half compared with the same system without SIL. Meanwhile the stable single-polarization lasing is achieved and the degree of polarization is improved from 0.165 to 0.989. Then the self-pulsation behavior of the DFB fiber laser is investigated in the injection-locked and unlocked system respectively and the output power fluctuation is reduced from about 4 to 0.1 dBm by injection locking. And the power output characteristics of the DFB fiber laser are also researched by changing the pump current. With increasing the pump current from 30 to 275 mA, the output power of the DFB fiber laser increases linearly and the injection-locked output increases slightly more quickly than the unlocked output. The results have a great potential application in optical communication and high sensitive fiber sensors.     

放电引发的非链式高功率重复频率HF/DF激光器

高功率重频HF/DF激光因其具有的波长和功率优势成为当前中红外激光技术发展的热点之一。介绍了利用紫外预电离横向放电结构和工作气体循环系统建立的放电引发高功率重频HF/DF激光装置。在对激光工作介质SF6/C2H6混合气体放电特性和激光输出特性研究的基础上,开展了强电负性气体的重频均匀体放电技术和气体快速循环置换技术研究,解决了泵浦源重频放电能量在气体介质中的有效沉积和提取问题,实现了激光器50Hz的重频稳定运行和能量稳定输出,HF激光的平均功率达到28W,脉宽100ns,峰值功率5.6 MW。     

Perfectly phase-matched third-order distributed feedback terahertz quantum-cascade lasers

We report a novel laser cavity design in third-order distributed feedback (DFB) terahertz quantum-cascade lasers based on a perfectly phase-matching technique. This approach substantially increases the usable length of the third-order DFB laser and leads to narrow beam patterns. Single frequency emissions from 151 apertures (5.6 mm long device) are coherently added up to form a narrow beam with (FWHM≈6×11°) divergence. A similar device with 40 apertures shows more than 5 mW of optical power with slope efficiency ～140 mW/A at 10 K pulsed operation.     

3.39μm He-Ne激光器稳定性研究

讨论了提高3 391 nm He-Ne激光器输出功率稳定性的相关技术问题.设计了适合该激光器的腔体结构,研究了放电参量和稳定性.在反射镜曲率半径与腔长比值为1.6,有效放电长度为0.2 m的情况下,得到了1.72 mW的多模连续输出,其光束发散角为6.43 mrad.在采用光反馈稳定技术后,功率输出的变化不大于2%.     

Nd∶YAG脉冲激光器双光路输出分时控制系统的设计

针对现有激光器多光路加工特点,采用Nd∶YAG脉冲激光器为光源,研制出激光器双光路输出分时控制系统。提出了具体的分时分光技术方案,设计出能够实现分时分光的分光装置,以及对装置的工作状态进行实时控制的分时控制电路,并确定了系统的程序流程。在不降低输出功率的前提下,实现了激光在不同时间、不同输出端口的输出,完成了分时分光。为避免因分光装置抖动而造成的光纤损坏,利用黑色相纸对光斑进行采样。结果表明：在全反镜改变位置后至激光输出,延时300 ms为最佳时间。该系统能实现激光的时分复用、动态分光,满足了多光路输出需求;而且系统的扩展能力强,能够根据实际激光加工状况,为激光加工设备的改进和升级提供思路。     

大功率780 nm半导体激光器的设计与制备

设计并制备了一款780 nm半导体激光器,并进行了外腔反馈锁模研究。利用金属有机化学气相沉积技术制备了激光器外延层,采用GaAsP/GaInP作为量子阱/波导层有源区,限制层采用低折射率AlGaInP材料。采用超高真空解理钝化技术,在激光器腔面蒸镀无定形ZnSe钝化层。未钝化器件在输出功率2.5 W时发生腔面灾变损伤（COD）,钝化后器件未发生COD现象,电流在10 A时输出功率10.1 W,电光转换效率54%。体布拉格光栅（VBG）外腔锁定前后,器件的光谱半峰全宽分别为2.6 nm和0.06 nm,VBG变温调控波长范围约230 pm。     

Low-frequency fluctuations in two-state quantum dot lasers

We study the feedback-induced instabilities in a quantum dot semiconductor laser emitting in both ground and excited states. Without optical feedback the device exhibits dynamics corresponding to antiphase fluctuations between ground and excited states, while the total output power remains constant. The introduction of feedback leads to power dropouts in the ground state and intensity bursts in the excited state, resulting in a practically constant total output power.     

小型多功能CO2激光器

研制了一种小型多功能CO2激光器。该激光器可以单脉冲、重频或连续方式输出,并可实现输出脉冲频率的编码及波长调谐。激光器谐振腔采用光栅一级振荡,零级输出的工作方式,分别利用声光调Q技术和脉冲放电技术实现了百ns至亚ms量级的脉冲激光输出。详细介绍了该激光器中基于光学角反射器原理设计的光栅调谐定向输出装置,并对其进行了理论计算和论证,实现了不同波长激光的定向、定位输出,获得调谐激光输出谱线超过60条,谱线分辨率优于0.01μm。激光器脉冲重复频率1Hz～10KHz连续可调,输出波长调谐范围9.2μm～10.8μm,激光器连续输出最大功率8W,重复频率1KHz时最小激光脉宽180ns,峰值功率4062W。该激光器在激光与物质相互作用科学领域,特别是激光对物质作用与破坏机理的研究方面具有重要的应用价值。     

Characterization of 60 GHz Multi Quantum well passively mode-locked laser under optical self-injection locking

The quality and pulse compression of the 60 GHz millimeter wave signals generated by 750 μm long InAlGaAs Multi Quantum Well (MQW) passively mode locked laser under free running and optical self-injection locked conditions are experimentally characterized in terms of longitudinal modes under certain bias currents that range from 24 mA to 90 mA. Initially, the MQW laser is characterized in free running condition with no external injection. The measurements reflect that the free spectral range of laser under test is around 61 GHz and exhibit more than 22 lasing modes. The laser is then integrated into low phase noise self-injection locking oscillator by feeding a part of output RF signal back into the laser cavity to enhance passive mode locking. By doing so the microwave line width of our laser is reduced from 900 kHz to 24 kHz with significant increase in output of resultant beat tones which exhibits strong passive mode locking. This is the first time that the free running microwave line width of MQW laser is reduced up to this level. It is evident from our experimental investigation that as we increase the power and phase correlation between different longitudinal modes inside laser cavity through optical self-injection, the strength of the passively mode locked mechanism is significantly increased and the phase noise of radio frequency signal is drastically reduced.     

High Stability Multi-Wavelength Source by Using Synchronized Etalon Filter in Superfluorescent Fiber Source

We demonstrate a new technique to generate a high stability multi-wavelength fiber source by inserting a synchronized etalon filter in superfluorescent fiber source. Multi-wavelength source can easily be obtained over the EDF gain region with the proposed schedule. By partially feedback diffracted spontaneous emission into erbium doped fiber medium, greater output power, extinction ration and narrower linewidth for each channel than that simply using the spectrum slicing technique is easy obtained. Stable output of multi-wavelength fiber source enables it to replace the DFB laser array with wavelength locker in DWDM application.