Femtosecond and continuous-wave laser performance of a diode-pumped Yb3+:CaYAlO4 laser

The cw and femtosecond laser operations of Yb(3+):CaYAlO(4) (Yb:CYA) are demonstrated. The laser emitted a maximum cw power of 1.94 W with a slope efficiency (η(slope)) of 71% and an optical-to-optical efficiency (η(opt)) of 51%. Under mode-locking operation, the laser emitted near transform-limited pulses with 156 fs pulse width, 8.1 nJ pulse energy and 0.74 W average power. The η(slope) and η(opt) of the mode-locked laser were 37% and 20%, respectively.     

Efficient passively Q-switched operation of a diode-pumped Nd:GGG laser with a Cr:YAG saturable absorber

The continuous-wave (cw) and passive Q-switching operation of a diode-end-pumped gadolinium gallium garnet doped with neodymium (Nd:GGG) laser at 1062 nm was realized. A maximum cw output power of 6.9 W was obtained. The corresponding optical conversion efficiency was 50.9%, and the slope efficiency was determined to be 51.4%. By using Cr⁴⁺:YAG crystals as saturable absorbers, Q-switching pulse with average output power of 1.28 W, pulse width of 4 ns and repetition rate of 6.2 kHz were obtained. The single-pulse energy and peak power were estimated to be 206 μJ and 51.6 kW, respectively. The conversion efficiency of the output power from cw to Q-switching operation was as high as 84.7%.     

An Actively Mode-Locked Ho:YAG Solid-Laser Pumped by a Tm-Doped Fiber Laser

An actively mode-locked Ho:YAG laser pumped by a diode-pumped Tm-doped fiber laser is reported.For the cw operation,we obtain the maximum output power of 3.43 W with a central wavelength 2022.2 nm at the maximum incident pump power of 11.4 W,corresponding to a slope efficiency of 34.5%.The beam quality factor M2 is 1.16,and the output beam is close to fundamental TEM_(00) In the case of the CWML operation,a stable pulse train is generated with an average output power up to 3.41 W with a slope efficiency of 34.3%at the incident pump power of 11.4 W and a pulse duration of 294 ps at a repetition rate of 81.92 MHz.In addition,the maximum single pulse energy is 41.6 n J.     

Power scaling of a continuous-wave and passively Q-switched Yb:KLu(WO<Subscript>4</Subscript>)<Subscript>2</Subscript> laser end-pumped by a high-power diode

The power scaling capacity of a diode end-pumped Yb:KLu(WO₄)₂ laser, operating in the continuous-wave (cw) and passively Q-switched regimes, has been investigated. A cw output power of 11.5 W was achieved with an optical-to-optical efficiency of 41% with respect to the incident pump power, while the slope efficiency amounts to 60%. The passively Q-switchedoperation yielded an average output power of 4.3 W at the fundamental wavelength of 1031.7 nm, and 1.15 W of Raman radiation at 1139.3 nm. The total slope efficiency for Q-switched operation was 40%. The highest pulse energy, duration, and peak power were 170 μJ, 2.2 ns, and 77.3 kW for the fundamental radiation, and 51 μJ, 2.3 ns, and 22.2 kW for the Raman radiation. PACS 42.55.Rz; 42.55.Xi; 42.55.Ye     

Spectroscopy and femtosecond laser performance of Yb3+:YAlO3 crystal

We report what we believe to be the first demonstration of cw and passively mode-locked Yb(3+):YAlO(3) (Yb:YAP) laser operation under diode pumping. Spectroscopic properties of a 0.6 at.%Yb(3+)-doped YAP single crystal were investigated. Output power up to 1.2 W with slope efficiency of 64.5% in the cw regime and 225 fs pulse duration with average power of 0.8 W from a mode-locked Yb:YAP laser were demonstrated.     

Continuous-wave and Q-switched laser operation of Nd:Gd0.18Y0.82VO4 mixed crystal

Efficient continuous-wave (cw), passively Q-switched, and actively Q-switched laser operations are demonstrated with a mixed vanadate crystal of Nd:Gd_0.18Y_0.82VO₄ under diode pumping. In a cw operation, an output power of 8.25 W is obtained at a maximum available incident pump power (P_in) of 15 W, with a slope efficiency of 56%. Using a Cr⁴⁺:YAG crystal of initial transmission of 62% as the saturable absorber for Q-switching, an average output power of 3.05 W is generated at pulse repetition frequency (PRF) of 16.7 kHz when the laser is pumped with the same maximum P_in. The pulse energy, pulse duration, and peak power are 183.3 μJ, 6.0 ns, and 30.6 kW, respectively. When actively Q-switched by an acousto-optic modulator, the laser produces an average output power of 5.5 W at PRF of 30 kHz with 16.2 W of pump power incident upon the laser crystal. The pulse energy, duration, and peak power are measured to be 183 μJ, 10.5 ns, and 17.5 kW, respectively.     

High-power diode-bar end-pumped Nd:YLF laser at 1.053 microm

We describe efficient cw operation of a Nd:YLF laser end pumped by two beam-shaped 20-W diode bars on the 1.053-microm transition. Fundamental transverse-mode operation with output power of 11.1 W for ~29.5 W of incident pump power was demonstrated. In Q-switched operation 8.4 W of average power at a pulse repetition frequency of 40 kHz and ~2.6-mJ pulse energy at a pulse repetition frequency of 1 kHz were achieved.     

Highly efficient, low-cost femtosecond Cr3+ :LiCAF laser pumped by single-mode diodes

We describe efficient continuous-wave (cw) and cw mode-locked operations of a Cr3+ :LiCAF laser, pumped by inexpensive single spatial mode laser diodes. Up to 280 mW of cw output power was obtained with 570 mW of absorbed pump power, with a corresponding slope efficiency of 54%. Continuous tuning between 765 and 865 nm was demonstrated using a fused silica prism. A semiconductor saturable absorber mirror was used to initiate and sustain stable, self-starting, mode-locked operation. In cw mode locking, the laser produced 72 fs (FWHM) duration pulses, and 1.4 nJ pulse energy, at an average output power of 178 mW. Electrical to optical conversion efficiencies of 7.8% in mode-locked operation and 12.2% in cw operation were demonstrated.     

Passively mode-locked Yb:YAG thin-disk laser with pulse energies exceeding 13 microJ by use of an active multipass geometry

We demonstrate the generation of high-energy picosecond pulses directly from a thin-disk laser oscillator by employing a self-imaging active multipass geometry. Stable single-pulse operation has been obtained with an average output power in excess of 50 W, excluding a cw background of 8%, at a repetition rate of 3.8 MHz. Self-starting passive mode locking was accomplished using a semiconductor saturable absorber mirror. The maximum pulse energy was 13.4 microJ at a pulse duration of 1.36 ps with a time-bandwidth product of 0.34. Single-pass external frequency doubling with a conversion efficiency of 60% yielded >28 W of average power at 515 nm.     

Femtosecond laser pumped by high-brightness coherent polarization locked diodes

We demonstrate, for the first time to our knowledge, the use of a coherent polarization locked diode as the high-brightness pump source for a femtosecond laser. Four diode emitters are coherently locked to produce more than 5 W linearly polarized, narrow linewidth, and single-lobed pump beam. This gives >10× brightness improvement over the conventional diode array. The diode beam is then used to pump a Yb:KYW laser to obtain 2 W output with 57% slope efficiency in cw laser operation. By using a saturable absorber mirror, we achieved cw mode-locking operation with a 177 fs pulse width at an average power of 0.55 W.     

LD端面抽运Nd:YAG 1319/1338nm双波长激光器研究

从LD端面抽运固体激光器的激光阈值公式出发,建立了双波长激光同时振荡的阈值条件,理论计算了腔镜对于两个波长的透过率关系,实现了LD端面抽运Nd:YAG 1319nm/1338nm双波长激光连续和准连续输出.双波长激光连续输出功率可达6W,斜效率为30%;准连续输出功率在重复频率50kHz时可达4.75W,斜效率为24.73%,脉冲宽度为55.05ns;腔内插入布儒斯特片,在重复频率为50kHz时,双波长激光准连续线偏振输出功率可达2.22W,不稳定性小于0.52%,M² 关键词： 端泵Nd:YAG激光器 1319nm/1338nm双波长 声光调Q 太赫兹波     

LD端面抽运Nd:YAG 1319nm/1338nm双波长激光器研究

从LD端面抽运固体激光器的激光阈值公式出发，建立了双波长激光同时振荡的阈值条件，理论计算了腔镜对于两个波长的透过率关系，实现了LD端面抽运Nd:YAG 1319nm/1338nm双波长激光连续和准连续输出.双波长激光连续输出功率可达6W，斜效率为30%；准连续输出功率在重复频率50kHz时可达4.75W，斜效率为24.73%，脉冲宽度为55.05ns；腔内插入布儒斯特片，在重复频率为50kHz时，双波长激光准连续线偏振输出功率可达2.22W，不稳定性小于0.52%，M²     

Efficient continuous-wave and Q-switched operation of a diode-pumped Yb:KLu(WO4)2 laser with self-Raman conversion

Efficient cw and passively Q-switched operation with self-stimulated Raman scattering conversion was demonstrated in a compact diode-pumped Yb:KLu(WO4)2 laser. A cw output power of 3.28 W was obtained with an optical efficiency of 48.2% and a slope efficiency of 78.2% with respect to the incident pump power. Stable Q-switched operation was achieved with a Cr4+:YAG saturable absorber, generating 32.4 microJ fundamental pulses with a duration of 1.41 ns at 1030.6 nm and 14.4 microJ Raman pulses with a duration of 0.71 ns at 1137.6 nm. At an incident pump power of 7.0 W, the average output power reached 0.9 and 0.4 W for fundamental and Raman radiation, with slope efficiencies of 32.1% and 14.1%, respectively.     

High-power high-repetition-rate acousto-optically Q-switched 1342 nm laser

A high-power high-repetition-rate acousto-optically Q-switched 1342 nm laser with double Nd:YVO₄ crystals pumped by fiber-coupled laser diodes is presented. The highest output power of 13.7 W was achieved with a total of 42 W pumping power in cw operation, the slope efficiency was measured as 36%, and the optical efficiency was better than 32%. In Q-switchedoperation, the highest pulse repetition rate of 100 kHz was obtained. At 50 kHz repetition rate, the laser exported 11.2 W average output power, with 60 ns average pulse width, ∼5% width stability (RMS) and ∼8% peak-power stability (RMS). At 10 kHz repetition rate, the highest average output power was measured as 6.3 W, single pulse energy was calculated as 0.63 mJ, with pulse width of 19 ns and peak-power higher than 30 kW. Combining the experimental results, we analyze and discuss some problems concerning Nd:YVO₄ crystal working at 1,342 nm wavelength. PACS 42.55.-f; 42.55.Xi; 42.60.Gd     

Continuous-wave wavelength conversion for high-power applications using an external cavity diamond Raman laser

We demonstrate continuous-wave (cw) operation of a diamond Raman laser at 1240 nm in an external cavity configuration. The output power increased linearly with pump power with a 49.7% slope efficiency and reached 10.1 W at the maximum available pump power of 31 W. The combination of resonator design with diamond provides a novel approach to power-scalable cw wavelength and beam conversion.     

Passively Q-Switched Ho:SSO Laser by Use of a Cr~(2+):ZnSe Saturable Absorber

A cw operation and a passively Q-switched(PQS) Ho:SSO laser(Cr~(2+):ZnSe as a saturable absorber) end-pumped by a Tm:YAP laser operating at near room temperature are reported. It is the first time to report a PQS Ho:SSO laser. For the cw mode, a maximum cw output power of 3.0 W is obtained, corresponding to a slope effciency of31.4%. For the PQS mode, a Cr~(2+):ZnSe is used as the saturable absorber, with transmission of 88.4% at 2112 nm.A maximum pulse energy of 1.29 mJ is obtained, corresponding to the pulse repetition frequency of 2.42 kHz. In this study, we change the distance between:Cr~(2+):ZnSe and the output mirror to research the pulse characteristic of the PQS Ho:SSO laser. The minimum pulse width of 73.5 ns is obtained, corresponding to the pulse energy of0.9 mJ and the pulse repetition frequency of 2.65 kHz.     

Diode-pumped passively Q-switched Nd:LuxY1−xVO4 laser at 1.34 μm with two V:YAG saturable absorbers

Laser performance with the mixed Nd:Lu_0.15Y_0.85VO₄ crystal at 1.34 μm wavelength has been demonstrated. The continuous wave (cw) operation was carried out in a simple plano-concave resonator with an optical conversion efficiency of 23% and a slop efficiency of 25%. At a pump power of 6.78 W, the Q-switched pulses with the largest average output power of 349 mW, the shortest pulse width of 30.6 ns, the largest repetition rate of 42.5 kHz, the highest peak power of 268 W and the largest pulse energy of 8.2 μJ were obtained, corresponding to the V:YAG with initial transmission of 89%.     

Diode-pumped, high-average-power femtosecond Cr3+ :LiCAF laser

We demonstrate a high-average-power continuous wave (cw) and cw mode-locked Cr3+ :LiCAF laser pumped by broad-area laser diodes. In cw lasing experiments, up to 580 mW of output was obtained with 4.35 W of incident pump. A semiconductor saturable absorber mirror was used to initiate stable, self-starting, mode locking. In the cw mode-locked regime, the Cr3+ :LiCAF laser produced nearly transform-limited, 67 fs long pulses near 800 nm with an average output power of 300 mW. The pulse repetition rate was 120 MHz, with a pulse energy of 2.5 nJ.     

High Power Continuous-Wave and Acousto-Optic Q-Switched Nd：GdVO4 Laser Operated at 912 nm

We present a high power and efficient operation of the ^4F3/2 → ^4I9/2 transition in Nd：GdVO4 at 912nm. In the cw mode, the maximum output power of 8.6 W is achieved when the incident pump power is 40.3 W, leading to a slope efficiency of 33.3% and an optical-optical efficiency of 21.3%. To the best of our knowledge, this is the highest cw laser power at 912nm obtained with the conventional Nd：GdVO4 crystal. Pulsed operation of 912nm laser has also been realized by inserting a small aeousto-optie （A-O） Q-Switch inside the resonator. As a result, the minimal pulse width of 20ns and the average laser power 1.43 W at the repetition rate of lOkHz are obtained, corresponding to 7.1 kW peak power. We believe that this is the highest laser peak power at 912nm. Furthermore, duration of 65ns has also been acquired when the repetition rate is 100 kHz.     

Diode-end-pumped passively mode-locked high-power Nd:YVO4 laser with a relaxed saturable Bragg reflector

We demonstrate a high-power passively mode-locked Nd:YVO (4) laser that uses a saturable Bragg reflector (SBR) with strain relaxation. 23.5 W of average power with ~21.5-ps cw mode-locked pulse trains was generated at a 50-W pump power. Experimental results show that appropriate strain relaxation in the SBR makes the mode-locking operation less sensitive to temperature variation.