Tunable optical parametric oscillator based on a KTP crystal,pumped by a pulsed Ti<Superscript>3+</Superscript>:Al<Subscript>2</Subscript>O<Subscript>3</Subscript> laser

We present the characteristics of an optical parametric oscillator based on a KTP crystal, pumped with noncritical phase matching by a pulsed Ti³⁺:Al₂O₃ laser, tunable in the range 677–970 nm. Tunable generation of signal and idler waves is obtained in the ranges 1030–1390 nm and 2690–3050 nm respectively. The efficiency of conversion of the pump to the signal wave is ≈23%, which for pulses of duration ≈8 nsec ensures an energy in the range 1.0–11.5 mJ. The width of the emission spectrum for the signal wave is within the range 0.8–1.8 nm and is predominantly determined by the linewidth of the Ti³⁺:Al₂O₃ pump laser. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 351–356, May–June, 2007.     

The optical properties and laser characteristics of Cr and Nd co-doped Y3Al5O12 ceramics

We have fabricated Cr³⁺ and Nd³⁺ co-doped YAG (Cr;Nd:YAG) ceramics, and investigated their optical properties and laser characteristics. The Cr;Nd:YAG has two broad absorption bands at around 440 nm (⁴A₂→⁴T₁) and 600 nm (⁴A₂→⁴T₂) respectively, caused by Cr³⁺ ions. In the case of pumping at 440 nm, the maximum effective lifetime of the Cr;Nd:YAG was 737 μs with a 0.1 at% Cr³⁺ and 1.0 at% Nd³⁺ co-doped YAG sample. Cr³⁺ ions take a role of an effective sensitizer to convert the UV light of flashlamp. For single-shot laser operation, a 10.4 J output energy at 1064 nm was obtained with 0.1 at% Cr³⁺ and 1.0 at% Nd³⁺ co-doped YAG ceramic rod with a laser efficiency of 4.9%. The laser efficiency was found to be more than twice that of a 1.0 at % Nd³⁺:YAG ceramic rod.     

Cr3+,Yb3+,Er3+共掺磷酸盐铒玻璃转镜调Q激光性质研究

研究了Cr³⁺,Yb³⁺,Er³⁺共掺磷酸盐铒玻 璃转镜调Q激光性质.三种Er₂O₃掺杂浓度的激光实验结果表明，在Er₂O₃名义掺杂浓 度为0.5wt％时，玻璃的综合激 光性质最好，重复频率为0.1Hz时，它的激光阈值功率为14.5mJ，最大输出能量为9.6mJ ，斜率效率为0.55％.在同种实验条件下，比较了Cr14和Kigre公司生产的QE-7S激光性质参数，实验表明，前者激光阈值功率稍低，而后者的斜率效率和最大输出功率略高. 关键词： 3+-Yb³⁺-Er³⁺共掺')" href="#">Cr³⁺-Yb³⁺-Er³⁺共掺 磷酸 盐玻璃 光谱性质 激光性质     

Numerical simulation of end-pumped CW Nd^3＋：GdVO4 laser at 1063 nm

A theoretical model to simulate an end-pumped CW Nd^3＋：GdVO4 laser at 1063 nm is presented. Its essence is to use the propagation equations to demonstrate the spatial evolutions of the pump and the laser powers in the cavity, hence it is applicable to both low and high gain lasers. The simulation results obtained by this model are in good agreement with the experimental observations reported in the literature for a Ti：sapphlre-pumped Nd^3＋：GdVO4 laser. Moreover, some parameters, such as the reflectivity of output coupler, the spot size of laser beam and the crystal length, are discussed with a view to optimizing the laser performance.     

共掺Na+的Yb3+∶CaF2晶体的荧光分析与低阈值激光运转

基于975nm激发的室温下荧光光谱测量，系统地研究了在新型钠、镱共掺的氟化钙晶体中钠离子的作用机理，分析了掺钠离子浓度与激光阈值的关系，获得了具有最低激光阈值的掺杂浓度优化配比. 激光实验表明对于2%Yb³⁺离子浓度的氟化钙，掺入3%的钠离子能够获得最低阈值的激光运转，这与理论和荧光分析完全一致. 关键词： 镱、钠共掺氟化钙 荧光光谱 激光阈值     

Tunable,narrow linewidth,linearly polarized and gain-switched Cr<Superscript>2+</Superscript>:ZnSe laser

We demonstrate a tunable, narrow linewidth, linearly polarized and gain-switched Cr²⁺:ZnSe laser pumped by a Tm, Ho:YVO₄ laser at 10 kHz pulse repetition frequency. By setting a quartz birefringent filter with a Brewster angle in the cavity, the linearly polarized Cr²⁺:ZnSe laser can be continuously tuned from 2.45 to 2.50 μm, and the output power was almost not changed. In addition, the linewidth was compressed to about 5 nm. At the incident pump power to the crystal of 14 W, the maximum output power of 2.84 W was obtained, corresponding to a slope efficiency of 20.4%.     

Diode-pumped passively Q-switched intracavity frequency doubled Nd:GdVO4/KTP green laser

A compact diode-pumped passively Q-switched intracavity frequency-doubled Nd:GdVO₄/KTP green-pulse laser was demonstrated, using Cr⁴⁺:YAG as a saturable absorber in a simple flat–flat cavity. With a 5.9 W incident pump power, a passively Q-switched green laser was obtained with an average power of 397 mW, repetition rate of 40 kHz, and pulse width of 40 ns, when the initial transmission of Cr⁴⁺:YAG was 85%. The shortest pulse width of 30 ns, the highest green peak power of 696 W and the maximum pulse energy of 21 μJ were obtained when the initial transmission of Cr⁴⁺:YAG was 70%. Under CW green operation, we obtained 440 mW output power.     

Laser and absorption saturation measurements of Cr crystals, pumped by broadband pulsed 940 nm radiation

The characteristics of a 940 nm pumped Cr⁴⁺:forsterite laser have been investigated using a pulsed colour centre laser as the excitation source. Laser threshold, slope efficiency and temporal behaviour have been determined for high and low Cr⁴⁺ doped material. 940 nm pumping is found to be more efficient than 532 and 730–770 nm excitation. Discrepancies with 1064 nm pumping are attributed to excited state absorption. Absorption saturation measurements have been used to assess the potential applications of Cr⁴⁺:forsterite, Cr⁴⁺:YAG and Cr⁴⁺: Lu₃A1₅O₁₂ (LuAG) as passive Q-switches for Nd lasers in the 940 nm region.     

Laser-induced,second-order optical susceptibilities of YAB:Cr3+ single crystals

Complex temperature studies of optically stimulated second harmonic generation (SHG) at 1064?nm for pulsed 10?ns Nd:YAG laser radiation under illumination of two coherent laser beams (at 1064?nm and its 532?nm second harmonic) were carried out by means of the Maker fringe method. The bicolour coherent process allowed detection of some additionally induced non-centrosymmetry. The effect was studied at different temperatures and experimental geometries in YAB:Cr³⁺ single crystals. We found that Cr³⁺ ions play a principal role in the observed effects. The output of optically stimulated SHG was generally non-spherical in the sequence profile, contrary to the traditional non-stimulated SHG. Moreover, we also established that the optimal conditions for obtaining SHG corresponded to the fundamental/writing beam intensities ratio 6:1. A specially performed control of the photo-thermal sample heating showed that the increase of temperature did not exceed 1.2?K, which allowed the influence of photo-thermal heating to be neglected. The optimal input–output laser geometry corresponded to s-p polarisation and to the angle of about 32° between the photo-inducing and fundamental beams. Additionally in the studied temperature range (77–295?K) there was observed an enhancement of the output second-order susceptibilities from 0.72?pm/V up to 1.02?pm/V.     

Investigation of Cr:YAG passive mode-locking in a pulsed Nd:YAG laser

Passive mode-locking of a pulsed Nd:YAG laser using a Cr⁴⁺:YAG saturable absorber was realized for the first time in a nearly critical stable resonator containing an antiresonant ring structure. The output energy and pulse duration are 13.5 mJ and 180 ps, respectively. The recovery time and saturable intensity for excited-state absorption of Cr⁴⁺:YAG under the action of strong laser pulses were calculated from rate equations.     

掺铬的镁橄榄石晶体连续波可调谐激光器

本文报道了连续波Nd:YAG激光器泵浦掺铬镁橄榄石(Cr⁴⁺:forsterite)晶体获得了连续波可调谐运转,该激光器采用Nd:YAG激光器的1.06μm谱线泵浦Φ5×9mm的Cr⁴⁺:forsterite晶体.在吸收泵浦功率为8.7W时,得到1.05W的连续波输出.当在腔内放置色散元件后,其调谐范围是1186nm～1306nm,同时详细研究了输出功率随温度和输出镜透过率的变化特性.     

Cr3+掺杂的Cd3Al2Ge3O12光谱特性及晶场参数计算

采用高温固相法合成了Cd₃Al₂Ge₃O₁₂：Cr³⁺多晶材料,利用X射线衍射对其结构进行了分析,通过Cr³⁺的室温吸收光谱、室温和77K发射光谱分别对其光谱特性和晶场参数进行了分析和计算.结果表明：在450 nm的蓝光激发下,Cd₃Al₂Ge₃O₁₂：Cr³⁺室温发 关键词： 3Al₂Ge₃O₁₂：Cr³⁺')" href="#">Cd₃Al₂Ge₃O₁₂：Cr³⁺ 荧光光谱 晶场参数 可调谐激光     

Wavelength tunable linear cavity cladding pump Er<Superscript>3+</Superscript>/Yb<Superscript>3+</Superscript>co-doped fiber laser operating in L-band

We have demonstrated a novel tunable linear cavity Er³⁺/Yb³⁺ co-doped fiber laser, which utilizes amplified spontaneous emission as a secondary pump source so that it can operate in L-band. The tuning wavelength range can be up to 34 nm, from 1588.6 to 1622.6 nm, and the output power excursion of the laser at different wavelengths can be less than 0.4 dB by using a two sections of high-birefringence fiber loop mirror as the wavelength filter. The high output power of 200 mW is realized by using the cladding-pump.     

Yb3+:Gd2SiO5晶体的结构和光谱性能

采用提拉法成功生长尺寸为φ30 mm× 75 mm的15at.%Yb³⁺:Gd₂SiO₅单晶, 并用Reitveld全谱拟合方法确定了其晶格常数、原子坐标和温度因子等参数. 用吸收光谱计算了Yb³⁺离子²F_7/2↔ ²F_5/2能级跃迁的振子强度、谱线强度、跃迁概率、 能级寿命和积分发射截面等光谱参数, 并根据激光性能评估得出结论: 表明该晶体具有较大的阈值特性, 有望采用大功率激光二极管泵浦实现可调谐或超快激光输出.     

高效率掺Tm~(3+)双包层光纤及光纤激光器的研制

掺Tm3+光纤激光器有着广泛的应用前景,而掺Tm3+光纤是其核心与关键.本文采用改进的化学汽相沉积(MCVD)工艺和气相液相复合掺杂技术,在MCVD机车上实现了掺Tm3+石英光纤预制棒的制备,并制备了掺Tm3+石英双包层光纤(芯包比为10/125).利用上述光纤搭建直腔型全光纤激光器,在波长为793nm的LD抽运下,获得激光光谱中心波长为2002 nm,最大的激光输出功率30.7 W,光纤斜率效率为59.32%.     

Optical parameters of Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses and their energy transfers at high temperature

This paper reports that a series of Nd³⁺:Er³⁺:Yb³⁺ co-doped borosilicate glasses have been prepared and their absorption spectra measured. The J--O intensity parameters Ω_k (k=2, 4, 6), spontaneous radiative lifetime τ_rad, spontaneous transition probability A, fluorescence branching ratio β and oscillator strength f_ed of the Nd³⁺ ions at room temperature are calculated based on Judd--Ofelt (J--O) theory. The temperature dependence of the up-conversion photoluminescence characteristics in a Nd³⁺:Er³⁺:Yb³⁺ co-doped sample is studied under a 978 nm semiconductor laser excitation, and the energy transfer mechanisms among Yb³⁺, Er³⁺ and Nd³⁺ ions are analysed. The results show that the J--O intensity parameters Ω₂ increase when the Nd³⁺ concentration of the Nd³⁺:Er³⁺:Yb³⁺ co-doped borosilicate glasses increases. The possibility of spontaneous transition is small and lifetimes are long at levels of ⁴F_5/2 and ⁴F_3/2. The intensity of Nd³⁺ emissions at 595, 691, 753, 813 and 887 nm are markedly enhanced when the sample temperature exceeds 400 K. The reasons being the cooperation of the secondary sensitization from Er³⁺ to Nd³⁺ and the contribution of a multi-phonon.     

Continuous-wave tunable Cr2+:ZnS laser

We report the first continuous-wave tunable over ∼280 nm around 2.3 μm room-temperature operation of a chemical vapor transport-grown and diffusion-doped Cr²⁺:ZnS laser, pumped by a Co:MgF₂ laser at 1.67 μm and generating over 100 mW of output power at 16% slope efficiency. The self-consistent results of the laser and spectroscopic analysis demonstrate a large potential of this crystal as an active medium for diode-pumped tunable mid-infrared sources. Received: 7 January 2002 / Revised: 14 March 2002 / Published online: 2 May 2002     

Spectral characterization and energy levels of Cr:Sc2(MoO4)3 crystal

This paper reports the spectral properties and energy levels of Cr³⁺:Sc₂(MoO₄)₃ crystal. The crystal field strength Dq, Racah parameter B and C were calculated to be 1408 cm⁻¹, 608 cm⁻¹ and 3054 cm⁻¹, respectively. The absorption cross sections σ_α of ⁴A₂→⁴T₁ and ⁴A₂→⁴T₂ transitions were 3.74×10⁻¹⁹ cm² at 499 nm and 3.21×10⁻¹⁹ cm² at 710 nm, respectively. The emission cross section σ_e was 375×10⁻²⁰ cm² at 880 nm. Cr³⁺:Sc₂(MoO₄)₃ crystal has a broad emission band with a broad FWHM of 176 nm (2179 cm⁻¹). Therefore, Cr³⁺:Sc₂(MoO₄)₃ crystal may be regarded as a potential tunable laser gain medium.     

Comparison of RTP electro-optic Q-switch and acousto-optic Q-switch in Tm,Ho:GdVO<Subscript>4</Subscript> laser

We demonstrate a tunable, narrow linewidth, linearly polarized and gain-switched Cr²⁺:ZnSe laser pumped by a Tm, Ho:YVO₄ laser at 10 kHz pulse repetition frequency. By setting a quartz birefringent filter with a Brewster angle in the cavity, the linearly polarized Cr²⁺:ZnSe laser can be continuously tuned from 2.45 to 2.50 μm, and the output power was almost not changed. In addition, the linewidth was compressed to about 5 nm. At the incident pump power to the crystal of 14 W, the maximum output power of 2.84 W was obtained, corresponding to a slope efficiency of 20.4%.     

利用光谱滤波器实现自启动的全光纤超短脉冲掺Yb3+光纤激光器

讨论了利用光谱滤波器实现自启动的被动锁模掺Yb³⁺光纤环形激光器的锁模机理,并研制出全光纤结构超短脉冲掺Yb³⁺光纤环形激光器.使用980 nm二极管激光器作为抽运源,高掺杂浓度掺Yb³⁺光纤作为增益介质.在净群速度色散为正的环形腔中加入光谱滤波器,抑制Yb³⁺离子在1030 nm强发射峰的同时,通过对啁啾脉冲的光谱滤波实现脉冲压缩.光谱滤波器与光纤非线性偏振旋转效应相结合,实现了激光器在1053 nm可自启动、十分稳定的锁模运转.激光器锁模阈值功率300 mW,平均斜率效率18.3%,最大输出功率53.07 mW,对应最大输出脉冲能量3.2 nJ.锁模光脉冲中心波长1053.6 nm,3 dB带宽10.84 nm,重复频率16.45 MHz.锁模脉冲宽度为皮秒量级,经腔外光栅对压缩至188 fs. 关键词： 3+光纤激光器')" href="#">掺Yb³⁺光纤激光器 自启动锁模 全光纤