双端泵浦固体激光器模匹配问题的实验研究

实验研究了高功率双端泵浦Nb:YVO₄固体激光器的谐振腔与泵浦光束的模匹配问题.实验发现了输出功率随激光在增益介质中模半径与泵浦光斑半径之比的变化规律.在低泵浦功率ω₀/ω_p<1的条件下,激光器输出功率随ω₀/ω_p的变化不敏感.但在高泵浦功率下,输出功率随ω₀/ω_p的减小而增加.ω₀/ω_p存在一个下限,无论泵浦功率的大小,当ω₀/ω_p低于此下限时基横模消失,高阶模出现.这对于高功率端面泵浦固体激光器腔型的设计具有一定的参考价值.     

高效率低阈值Nd:S-FAP晶体激光特性

测量了新型晶体Nd:S-FAP[Nd:Sr₅(PO₄)₃F]的吸收光谱特性,它具有宽的有效吸收带,在575.0nm和805.4nm处有二个强的吸收峰.用可调谐染料激光器测量了575.0nm处的吸收系数为19.7cm^-1,用波长为575.0nm的的染料激光作泵浦源,实现了1.059μm的全偏振光输出,最低闽值为2.5mJ,斜效率为49%.用KTP倍频获得的绿光的波长为0.5295μm,峰值半宽度为1.0nm.     

单光子波长调制吸收光谱用于1.5 μm激光器的波长锁定

提出了一种kHz调制频率量级的单光子调制技术,实现对激光器的实时锁定. 通过探测乙炔气体的单光子吸收光谱,对离散的单光子响应脉冲进行锁定放大, 获得激光器频率锁定的鉴频曲线.将1.5 μm分布反馈半导体激光器的输出频率稳定在乙炔气体 ν₁ + ν ₃带P5e支吸收峰上,在175 s内典型激光频率起伏小于25 MHz. 这种基于单光子波长高频调制吸收光谱的稳频技术消除了低频段较高背景的噪声, 可应用于单光子量级的量子保密通讯系统以及光学波分复用系统.     

高边模抑制比窄线宽的光纤光栅外腔半导体激光器

本文从耦合腔理论出发分析了光纤光栅外腔半导体激光器的模式选择,得到了为达到稳定的高主边模抑制比所需的短外腔、短光纤光栅的器件设计原则.制作了两只光纤光栅外腔半导体激光器,Q₁为短外腔(<2mm)、短光纤光栅(4mm)结构,Q₂为长外腔(20mm)、长光纤光栅(17mm)结构.测量Q₁的主边模抑制比为35dB,Q₂的主边模抑制比为10dB.     

量子阱半导体激光器的光束质量

本文给出了一种非截取地收集非傍轴激光束,并把它变换成傍轴光束的方法,将之运用到量子阱半导体激光器的实验中发现了一些重要的现象.经过测量和计算得到它垂直于结方向的等效光束质量原子M_y²明显小于1,根据该结果对半导体激光器的设计和使用提出了建议.     

晶体热效应对LD端面泵浦固体激光器优化设计的影响

考虑了激光介质因受热不均匀而引起的热效应对激光器衍射损耗和谐振腔基模尺寸的影响,利用M²因子来描述泵浦光在激光介质中的传播规律,根据泵浦光在激光介质中的有效泵浦体积最小以提高泵浦效率这一判据,给出了含有泵浦光束质量因子M_p²和激光介质参量在内的端面泵浦固体激光器的优化设计曲线,利用这些曲线可方便地指导完成激光器的最佳化参量选择.利用上述理论,对LD端面泵浦光纤耦合输出的Nd:YVO₄激光器进行了研究,实验结果和理论分析相符合.     

InGaAsP SBH激光器光束质量的非傍轴分析

计算了InGaAsPSBH激光器的TE₀₀模,并利用非傍轴矢量矩理论,分析了平行于p-n结方向上的光学质量因子M_y²在以往有关M²的计算中,往往忽略了包层中光场的贡献,因此得出M²小于1的结论当半导体激光器的激活层的尺寸远小于发射波长时,大部分光场将渗透到包层中,因此,包层的光场是不能忽略的考虑到激活层和包层中的光场对M²的影响,给出了非傍轴半导体激光M²的精确表达式结果表明,M_y大于1.     

用于准相位匹配的LD泵浦Nd:YAG946nm连续激光光源

本文为泵浦质子交换准相位匹配波导器LiNbO₃提供了激光光源,用808nm半导体激光器泵浦Nd:YAG晶体,在室温下获得946nm激光连续输出大于120mW,斜率效率9.8%,并且在国内首次实现了LD泵浦Nd:YAG/KNbO₃473nm蓝色激光器的连续运转,报道了初步的实验结果并对此进行了详细的分析,提出了改进方案.     

1313nm脉冲泵浦下掺Er3+光纤中多波长可见光的产生

本文报道了以1313nmNd:YLF激光脉冲泵浦掺饵(Er³⁺)单模GeO₂/SiO₂光纤而产生多波长可见光的实验,在该光纤中观察到(463～510)nm间的多波长放大自发辐射过程,此过程对应于Er³⁺离子的²G_7/2等几个激发态到⁴I_13/2亚稳态的跃迁.其激发过程是分步的四光子吸收过程,同时,掺饵光纤的红外发射峰1530nm(⁴I_13/2-⁴I_15/2)与1313nm泵浦光之间的三波混频过程也对这一区间的连续多峰的光谱结构有贡献.实验中还观察到540nm附近的绿光辐射.     

铯原子调制转移光谱在激光稳频中的应用

利用铯原子D₂线的调制转移光谱的鉴频特性,实现了光栅外腔式主振荡器-功率放大型(MOPA)半导体激光器相对于铯原子6²S_1/2F=4→6²P_3/2 F’=5超精细跃迁的偏频锁定,在100 ms内激光频率的相对起伏小于±280 kHz.相对于一般的饱和吸收锁频方法而言,调制转移光谱在锁频中的应用不仅彻底消除了Doppler背景对锁频的影响,而且还避免了对激光器直接进行频率扰动而带来的附加频率噪音.     

Improvement in the laser performances of an A-O Q-switched Nd:GdVO<Subscript>4</Subscript> laser by direct-diode pumping into the emitting level

The laser performances of an A-O Q-switched Nd:GdVO₄ laser are demonstrated under LD pumping at 808 and 879 nm, respectively. Results indicate that the pulse performances are improved markedly under 879-nm LD direct pumping. At a repetition rate of 100 kHz, a maximum average output power of 12.1 W, a pulse width of 20.3 ns, and a peak power of about 6 kW are reached under 879-nm pumping.     

The LD end-pumped Q-switched solid-state laser design software based on the adaptive method

In the LD end-pumped acousto-optic (A-O) Q-switched solid-state laser, according to the requirements of users on the laser peak power, the pulse width, the repetition rate and the beam quality factor M², if the main parameters of the pumping source and the laser resonator can be pre-designed by a software, will effectively guide experiments, and save cost. A kind of laser design software is introduced in this paper, which is based on the adaptive adjustment method and using MATLAB/C mixed programming. According to the user requirements, a compact LD end-pumped A-O Q-switched Nd:YAG laser which peak power is 100-kW-class can be designed and actual outputs can be calculated based on the design results. Drawing the laser pulse waveform, analyzing of the thermal effect in laser gain medium and drawing the temperature distribution map, exporting and saving the data are the additional functions of this software.     

镱铝共掺石英玻璃的制备及其发光特性的研究

提出了一种新的溶液掺杂与非化学气相沉积(non-chemical vapor deposition, NCVD)熔融相结合的方法制备稀土掺杂石英基玻璃,并采用该方法制备出组分为98SiO₂-0.5Yb₂O₃-1.5Al₂O₃wt%、折射率n_D =1.519和密度 ρ=2.62 g/cm³的镱铝共掺石英玻璃.经实验测试表明:它的 关键词： 镱铝共掺石英玻璃 溶液掺杂 发光特性 光子晶体光纤     

Improvement of performance characteristics of deep violet InGaN DQW lasers using a strip DQW active region

The effect of the laser ridge width on the performance characteristics of deep violet In_0.082Ga_0.918N/GaN double quantum well (DQW) laser diodes (LDs) has been numerically investigated. Simulation results indicated that threshold current of LDs is decreased and slope efficiency and differential quantum efficiency (DQE) are increased by decreasing ridge width, whereas output power is decreased. The results also showed that a decrease of more than 1 μm in the ridge width reduces the threshold current, whereas the slope efficiency, output power, and DQE are decreased. A new DQW LD structure with a strip active region has been proposed to obtain a lower current threshold and higher output power, slope efficiency, and DQE. The results showed the InGaN DQW LD with a strip DQW active region has the highest output power, slope efficiency, and DQE; it also has a lower threshold current compared with that of the original LD. The comparative study conducted for the LDs with output emission wavelengths of 390, 414 and 436 nm has also confirmed the enhancement in LD performance using the strip DQW active region structure.     

Yb3+离子掺杂钨酸钾钆晶体的光谱参数

从Yb³⁺:KGd(WO₄)₂(KGW)的吸收谱和荧光谱出发,利用倒易理论计算其各个光谱参量,如吸收截面,受激发射截面,辐射寿命等.由于Yb³⁺:KGW晶体较适合用作二极管泵浦的激光器的材料,而激光二极管所发出的光是偏振光,晶体又是双折射晶体,因此研究了泵浦光的不同通光方向和偏振方向对Yb³⁺:KGW晶体荧光光谱的影响.实验表明在不同情况下其对晶体荧光强度影响较大,因此在设计用激光二极管泵浦的激光器时,应考虑合适的泵浦光偏振方向和入射在晶体上的轴向,其中泵浦光的通光方向比泵浦光偏振方向对晶体的荧光强度的影响更大.对按晶轴切割的这两种晶体,相同实验条件下,荧光强度I_c>I_b>I_a.对于按折射率主轴切割的来说,荧光强度I_Np>I_Ng>I_Nm.在通光方向为c轴,偏振方向平行b轴时得到了最大的荧光强度.     

High-contrast all-optical switching with Pt:ethynyl complex

We have theoretically analyzed all-optical switching in Pt:ethynyl complex based on nonlinear excited-state absorption. A detailed analysis for Pt:ethynyl complex has been presented based on rate equation approach. It is shown that a pulsed pump laser beam at 355 nm switches the transmission of a cw probe laser beam at 633 nm through a Pt:ethynyl sample. The effect of various parameters, such as pump pulse width, peak pumping intensity, normalized parameter , transition times of S₁→S₀ and S₁→T₁ states and lifetime of triplet state, on switching characteristics has been analyzed in detail. It has been shown that the probe beam can be completely switched off (i.e. 100% modulation) by a pulsed pump laser beam at 50 kW/cm². These results have been used to design all-optical NOT and the universal NOR and NAND logic gates with multiple pump laser pulses.     

Photoquenching parameters for commonly used laser dyes

Laser dyes which are commonly used in pulsed laser pumped dye laser (PLPDL) systems have been investigated. It is shown that photoquenching plays an important role in the pumping process of all laser dyes, determining the efficiency of the PLPDL. Molecular parameters, such as absorption cross sections at various pumping wavelengths and fluorescence lifetimes of theS _n (n>1) excited electronic states of laser dyes, have been determined utilizing the photoquenching technique.     

Slope efficiency of up to 73% for Yb:Ca4YO(BO3)3 crystal laser pumped by a laser diode

Yb:Ca₄YO(BO₃)₃ (Yb:YCOB) crystal with good quality and large size has been grown by the Czochralski method. The polarization absorption and fluorescence spectra have been measured. The laser action of the Yb:YCOB crystal has been demonstrated when it is pumped by a fiber-coupled laser diode (LD) at the wavelength of 976.4 nm. The pumping threshold is 55 mW, the light-light conversion efficiency is 58.7%, and a slope efficiency of up to 73% is thus calculated. Received: 16 December 1998 / Revised version: 4 February 1999 / Published online: 7 April 1999     

First diode-pumped Yb-doped solid-state laser continuously tunable between 1000 and 1010 nm

We demonstrate that the ytterbium-doped medium Yb:YSO can provide laser oscillation in the 1000–1010 nm wavelength range under diode pumping around 980 nm. Ytterbium-doped Y₂SiO₅ crystal has been chosen for its high emission cross section around 1 m combined with a strong absorption line at 978 nm. We have developed an original pumping architecture that permits us to overcome problems due to the small difference between pump and laser wavelengths. In this way, laser emission continuously tunable in the 1000–1010 nm wavelength range has been obtained with more than 100 mW of output power. This kind of laser is the first step toward a metrological source around 500 nm stabilized on an I₂ absorption line. Furthermore, 100 mW of laser light has been obtained at 998.5 nm, leading to a remarkably low quantum defect of 2.1%. PACS 42.55.Xi; 42.60.Pk; 42.72.Ai     

Diode-pumped Q-switched Nd:Y<Subscript>0.5</Subscript>Lu<Subscript>0.5</Subscript>VO<Subscript>4</Subscript> laser double-modulated with an acousto-optic modulator and Cr<Superscript>4+</Superscript>:YAG saturable absorber

A diode pumped Nd:Y_0.5Lu_0.5VO₄ pulse laser modulated with an acousto-optic (AO) Q-switcher and Cr⁴⁺:YAG saturable absorber is first demonstrated in this paper. The laser is shown to generate shorter pulse width than AO Q-switched laser alone, and have a higher peak power and single pulse energy than passively Q-switched laser with only Cr⁴⁺:YAG. A laser pulse width of 6.16 ns and a peak power of about 43.83 kW are achieved at the incident pumping power of 14.09 W.