Diode pumped actively mode-locked Tm:YAlO3 laser

CW acousto-optical mode-locked diode pumped Tm:YAlO₃ laser at 1.936 μm was experimentally studied. Lasing with output power ～100 mW, pulse repetition rate 103.4 MHz and laser pulse durations in the range of 30–200 ps was realized. The problem of laser intensity stabilization is discussed.     

Comparative study of pulsed laser diode end-pumped thulium-doped 2-µm Q-switched lasers

We report pulsed laser diode(LD)end-pumped acoustic Q-switched Tm:YAG laser,Tm:LuAG laser,and Tm:LuYAG laser and the physical properties and spectra of Tm:YAG,Tm:LuAG,and Tm:LuYAG are analyzed.The Tm:LuYAG laser is pumped by 785-nm and 788-nm pulses separately,and is compared with Tm:YAG laser.Different output energy values and output wavelengths of Tm:LuAYG lasers pumped by LDs with different wavelengths are obtained and compared with each other.When the repetition frequency is 100 Hz,the pulsed Tm:YAG laser has single pulse energy of 15.9 mJ,pulse width of 126.7 ns,and the center wavelength of 2013.36 nm,and the pulsed Tm:LuAG laser possesses single pulse energy of 11.8 mJ,pulse width of 252.4 ns,and the center wavelength of 2023.65 nm,and the pulsed Tm:LuYAG laser output energy values are 12.32 mJ and 12.25 mJ with the slope efficiencies of 12.5%and 11.85%,the center wavelengths of 2017.89 nm and 2027.11 nm,respectively,while the pump sources are 785-nm and 788-nm pulsed LDs,respectively.     

Q-switched operation of an in-band-pumped Ho:LuAG laser with kilohertz pulse repetition frequency

We report continuous-wave (CW) and repetitively Q-switched operation of an in-band-pumped Ho:LuAG laser at room temperature. End-pumped by a Tm:YLF solid-state laser with emission wavelength of 1.91 μm, the CW Ho:LuAG laser generated 5.4-W output at 2100.7 nm with beam quality factor of M ²～1.03 for an incident pump power of 14.1 W, corresponding to slope efficiency of 67% with respect to absorbed pump power. Up to 1.5-mJ energy per pulse at pulse repetition frequency (PRF) of 3 kHz and 4.5-W average power with FWHM pulse width of 28 ns at 5 kHz were demonstrated in repetitively Q-switched operation.     

A Diode-Pumped Actively Q-Switched and Injection-Seeded Tm:LuAG Laser at Room Temperature

We elaborate a diode-end-pumped actively Q-switched injection-seeded Tm:LuAG laser. To achieve power scaling with good beam quality, we construct a more flexible laser with longer cavity accommodated strongly aberrated thermal lens in a Tm:LuAG laser and took special care in designing the laser resonator. Under Q-switched operation, we achieve a maximum output energy of 2.6 mJ with a pulse width of 318.2 ns at a pulse repetition frequency of 50 Hz. To control the spectral, temporal, and phase characteristics of the Tm:LuAG laser, the ring laser is injected by a seed laser, which provides a 50 mW single longitudinal-mode laser output at a wavelength of 2,022.6 nm. We achieve an output energy of 1.8 mJ with a pulse width of 293.0 ns after employing the injection seed.     

能量传递上转换对Tm，Ho：YLF调Q激光器上能级寿命的影响

根据激光二极管纵向抽运Tm,Ho：YLF激光器的能级跃迁和能量传递过程，在考虑能量传递上转换(ETU)的情况下，建立了Tm,Ho：YLF主动调Q激光器的准三能级速率方程，得出了激光单脉冲能量的解析表达式.在理论上指出，能量传递上转换不但减小了输出单脉冲能量，而且严重减小了激光上能级寿命.实验上给出了在固定抽运功率下，单脉冲能量随重复频率的变化关系，验证了理论所指出的能量传递上转换减小了激光上能级寿命. 关键词： 二极管抽运 Tm Ho：YLF晶体 能量传递上转换 速率方程     

Ho:YAG laser intracavity pumped by a diode-pumped Tm:YLF laser

We report a compact Ho:YAG laser that is intracavity pumped by a diode-pumped Tm:YLF laser. Both lasers exhibit pulse mode behavior. Operating both crystals at room temperature (25 degrees C), we obtained 1.6 W of average output at 2.09 microm from the Ho:YAG laser for 15.4 W of diode power incident upon the Tm:YLF rod and a slope efficiency of 21%.     

Tm:germanate fiber laser: tuning and Q-switching

A Tm:germanate fiber laser produced >0.25 mJ/ pulse in a 45 ns pulse. It is capable of producing multiple Q-switched pulses from a single pump pulse. With the addition of a diffraction grating, Tm:germanate fiber lasers produced a wide, but length dependent, tuning range. By selecting the fiber length, the tuning range extends from 1.88 to 2.04 μm. These traits make Tm:germanate lasers suitable for remote sensing of water vapor. PACS 42.55.Wd; 42.55.Xi     

1.2 W中红外ZnGeP2光参量振荡器

报导了利用Tm,HoGdVO4激光器抽运双谐振ZnGeP2光参量振荡器实验研究.Tm(5%),Ho(0.5%)GdVO4晶体采用液氮制冷方式,工作在77 K温度条件下.以25 W波长为800 nm的光纤耦合激光二极管抽运,2 μm激光最大平均功率7 W,脉冲宽度小于30 ns, 脉冲重复频率5 kHz到20 kHz可调.非线性频率转换晶体ZnGeP2长15 mm,55?切割,OPO谐振腔为平平腔,腔长约25 mm.在5W的2 μm激光抽运下,脉冲重复频率10 kHz,实现了信号光3.7 μm及闲频光4.5 μm中红外激光输出,参量光脉冲宽度为15～17 ns,最大平均功率大于1.2 W,光-光转换效率为20%.测量参量光输出光束全宽度远场发散角4 mrad,光束质量M2因子小于3.     

600-mJ,double-pulse 2-microm laser

An efficient double-pulse Ho:Tm:YLF 2-microm laser with total Q-switched output energy of 600 mJ has been demonstrated. A double-pulse pair is obtained per pump pulse. By operation of the laser in a double-pulse format, the residual energy stored among the Tm ions is transferred to the Ho atoms that were de-excited by the extraction of the first Q-switched pulse. Thus, the overall laser efficiency is increased by 61%.     

The comparative analysis and optimization of the free-running Tm<Superscript>3+</Superscript>:YAP and Tm<Superscript>3+</Superscript>:YAG microlasers

The thulium microlasers based on yttrium-aluminium perovskite and yttrium-aluminium garnet crystals are considered as coherent light sources at the wavelength near 2 μm. The comparative analysis of these lasers is carried out by means of the lasers’ parameters optimization for each value of the pumping power taking into consideration the cross-relaxation and up-conversion processes as well as heating of the active medium. The optimal values of the active medium length, activator concentration and the output mirror reflectivity are determined both for Tm:YAP- and Tm:YAG-laser. The pulse generation of Tm:YAP- and Tm:YAG-lasers is also considered, the parameters of this regime are determined. The comparison shows the suitability of Tm:YAP laser crystal both for cw and pulse generation. The up-conversion influence on the laser characteristics is also analyzed. PACS 42.60.Gd     

Single-frequency distributed Bragg reflector Tm:YAG ceramic derived all-glass fiber laser at 1.95 μm

A 135 mW single-frequency distributed Bragg reflector fiber laser at 1.95 μm was obtained based on a Tm:YAG ceramic-derived all-glass fiber. The fiber laser achieved an optical signal-to-noise ratio of ～ 77 dB. Moreover, the threshold and linewidth of the single-frequency laser were measured to be 15.4 mW and 4.5 kHz, respectively. In addition, the measured relative intensity noise was less than -140 dB· Hz^-1 at frequencies of over 10 MHz. The results show that the as-drawn Tm:YAG ceramic-derived all-glass fiber is highly promising for ～ 2 μm single-frequency fiber laser applications.     

Single-frequency operation of a laser diode side-pumped Q-switched Tm:YAG laser using seeding injection technique

A laser diode (LD) side-pumped 2 μm single-frequency Q-switched Tm:YAG laser was demonstrated. The laser was injection seeded by a CW single frequency Tm:YAG laser with a twisted-mode cavity. The maximum single-frequency pulse energy was 16.3 mJ, with a pulse width of 570 ns and a pulse repetition rate of 10 Hz. The linewidth of the 2 μm single-frequency Q-switched laser was 0.68 MHz, measured by using the optical heterodyne technique. The M ² of the laser beam was measured to be 1.09 and 1.03 for x direction and y direction, respectively.     

激光二极管抽运(Tm,Ho)∶YLF激光器光谱特性实验分析

Ho∶YLF晶体的5I7和5I8斯塔克能级分裂数较多,形成2047~2070nm宽的增益谱带,对于可调谐2μm激光及宽带激光放大器研究具有重要意义。理论上分析了(Tm,Ho)∶YLF晶体的能级结构,并对晶体掺杂浓度和长度进行了优化。实验研究了激光二极管抽运微片Tm(原子数分数0.06),Ho(原子数分数0.004)∶YLF激光谱线可调谐特性,调谐范围2.0656~2.0671μm。利用(Tm,Ho)∶YLF晶体的宽增益谱特性,将其作为激光二极管抽运激光放大器,成功地将2.048μm(Tm,Ho)∶GdVO4激光功率放大了2.5倍。实验上测量了(Tm,Ho)∶YLF晶体在强抽运条件下480~492nm及530~550nm可见波段的上转换蓝绿光荧光谱。     

Efficient continuous wave and Q-switched operation of a dual-end-pumped <Emphasis Type="Italic">c</Emphasis>-cut Tm:YAP laser

An efficient continuous wave (CW) and Q-switched c-cut Tm:YAP laser is reported in this letter. With the dual-end-pumped convex-concave resonator, CW output power up to 13.6 W at 1.99 μm was obtained under a total incident pump power of 50 W. The corresponding slope efficiency was 34.3% and conversion efficiency was 27.2%. The active Q-switched operation of the laser had an average output power of 12.5 W at 10 kHz pulse repetition frequency, with a minimum pulse width of 126 ns. With 6 kHz pulse repetition frequency, the maximum pulse energy of 1.6 mJ was obtained. In addition, using the Tm:YAP laser as a pumping source for gain-switched Cr:ZnSe laser, as much as 4 W output power in the wavelength range of 2.5–2.6 μm was obtained.     

Tm,Ho双掺调Q激光系统理论与实验研究

本文针对Tm,Ho双掺的激光系统,利用速率方程理论,得出了激光各能级的反转粒子数分布规律.通过计算预测出了超过1 ms的时间有巨脉冲的光子输出,脉冲能量为88.4 mJ,脉冲宽度为426 ns.实验采用环形腔声光调Q,Tm,Ho:LuLF为激光介质,三向侧面抽运.自由运转和调Q状态的斜率效率分别为6.36%和2.9%.注入能量3.25 J时,自由运转激光能量103.2 mJ,调Q激光能量为30.3 mJ,对应光-光效率为3.17%,0.93%;注入能量3.5 J时,自由运转激光能量为129.3 mJ,调Q激光能量35.9 mJ,对应光-光效率为3.69%,1.02%.最大的动静比为32.8%.激光脉冲宽度为417.2 ns.如果环形腔能够单向运转,那么得到的激光能量和光-光转换效率都将增大一倍,与预测结果更加一致.     

High repetition rate Tm：Ho：LuLiF master-oscillator and Tm-doped fiber power-amplifier system

A high repetition rate Tm:Ho:LuLiF master-oscillator and polarization-maintaining (PM) Tm-doped fiber power-amplifier system is presented.A 11.3-kHz,0.4-nm line width,0.89-W Tm:Ho:LuLiF seed laser is developed.Using a two-stage PM Tm-doped fiber power amplifier system,32.4-W output power is obtained with 0.4-nm line width at a central wavelength of 2058.5 nm,corresponding to 0.66-W seed laser.The laser spectrum and pulse profile are measured.     

Simulation of laser dynamics and active Q-switching in Tm,Ho : YAG and Tm : YAG lasers

 We developed a detailed rate equation model to study laser dynamics and active Q-switching in Tm,Ho: YAG and Tm:YAG lasers. The simulation results agreed well with published experimental data, as well as provided new insights for optimizing pulse generation. Received: 7 March 1996/Accepted: 28 May 1996     

Pulsed and cw Cr,Tm:YAG laser with simultaneous diode and flashlamp excitation

A Cr,Tm:YAG laser, under simultaneous flashlamp and diode laser excitation, was demonstrated. With respect to diode pumping a cw-output power of 35 W with a slope efficiency of 20% was achieved. With flashlamp excitation pulse energies up to 465 mJ were realised. This operation was supported by simultaneous diode pumping to bring the laser close to threshold. Repetition rates up to 10 Hz were demonstrated with this simultaneous pumping mode of the Cr,Tm:YAG laser crystal.     

高脉冲重复频率调Q Tm,Ho:GdVO4激光器

报道了一个高效率连续波和调Q高重频两种运行方式的Tm,HoGdVO4激光器.Tm,HoGdVO4晶体尺寸4 mm×4 mm×7 mm,a轴通光,液氮制冷到100 K,由发射中心波长为793 nm的光纤耦合激光二极管端面泵浦.Tm,HoGdVO4激光连续波输出功率4.0 W,光光转换效率26%.声光调Q条件下输出平均高功率3.9 W,脉冲重复频率10 kHz,脉冲宽度50 ns. 通过减小声光Q开关的开启时间,激光脉冲宽度由50 ns减小至23 ns.在10 kHz重频下,测量最大脉冲能量0.39 mJ , 峰值功率7.8 kW.     

High-Power Diode-End-Pumped Slab Composite Tm:YLF Compact Laser

We design a continuous-wave Tm:YLF laser with a composite slab crystal end-pumped by two fiber-coupled laser diodes at room temperature. We achieve a maximum continuous wave output power of 105 W for the bonded slab Tm:YLF laser; the corresponding slope efficiency is 47.7% and the optical-to-optical conversion efficiency is 42.0% with respect to the incident pump power. The laser operated at 1,907.5 nm with a beam quality factor of M² ～3.2 at the highest output power.