Diode-pumped Kerr-lens mode-locked Yb:KY(WO(4))(2) laser

A self-starting Kerr-lens mode-locked Yb:KY(WO(4))(2) laser directly end pumped by two 1.6-W diodes is demonstrated for what is to our knowledge the first time. Pulses as short as 71 fs with 120-mW average output power, at a center wavelength of 1057 nm, were obtained at a repetition rate of 110 MHz. A 10-nm tuning range was achieved with longer pulses and higher average output power.     

Lu, Gd codoped KY(WO(4))(2):Yb epitaxial layers: towards integrated optics based on KY(WO(4))(2)

Codoping KY(WO(4))(2):Yb layers with optically inert Lu and Gd ions allows a large increase of the refractive index contrast with respect to KY(WO(4))(2) substrates. This paves the way for the realization of integrated optical circuits based on this very promising material. First riblike waveguide structures have been fabricated and propagation losses below 1 dB/cm have been evaluated. A Y-junction with a splitting ratio close to 1:1 and additional losses of 1.4 dB has also been demonstrated.     

Directly diode-pumped Colquiriite regenerative amplifiers

The Colquiriite crystals are attractive materials for directly diode-pumped femtosecond oscillators and amplifiers. Cr:LiSAF, Cr:LiSGAF and Cr:LiCAF are for the first time directly compared for their use in regenerative amplifiers both experimentally and theoretically. A maximum pulse energy of 10 μJ was obtained at an absorbed pump power of 1.1 W. A review of the work is given including a Cr:LiSAF seed oscillator, outlining specific needs for seeding.     

Directly diode-pumped Yb3+:SrY4(SiO4)3O regenerative amplifier

We report a regenerative amplifier based on an Yb-doped apatite crystal: Yb3+:SrY4(SiO4)3O (Yb:SYS). We obtained 420-fs pulses at a central wavelength of 1066 nm with an energy of 100 microJ at 300 Hz after compression. To the best of our knowledge, this system is the first regenerative amplifier based on an Yb:SYS crystal and provides duration among the shortest ones generated by a directly diode-pumped regenerative amplifier.     

Pulsed laser operation of Y b-dope d KY(WO(4))(2) and KGd(WO(4))(2)

Spectroscopic properties and laser performance of Y b-doped tungstates at pulsed Ti:sapphire laser pumping are reported. Room-temperature lasing near 1025nm is demonstrated in Yb:KY(WO(4))(2) and Yb:KGd(WO(4))(2), with a slope efficiency as great as 86.9%.     

Efficient femtosecond green-light source with a diode-pumped mode-locked Yb3+:KY(WO4)2 laser

Efficient generation of femtosecond pulses at 524 nm is demonstrated by the extracavity frequency doubling of the output of a diode-pumped femtosecond Yb3+:KY(WO4)2 laser using a periodically poled LiTaO3 crystal. An average second-harmonic power of 120 mW is produced at an internal conversion efficiency of 40%. The temporal characteristics of the frequency-doubled pulses as a function of focusing conditions in a thick nonlinear crystal are investigated experimentally, and pulses as short as 225 fs are generated at a pulse repetition frequency of 86 MHz.     

Ultrafast thin-disk Yb:KY(WO4)2 regenerative amplifier with a 200-kHz repetition rate

We report an Yb:KYW thin-disk amplifier system that provides ultrashort pulses in the 10-microJ energy range at high repetition rates. The thin-disk concept uses large laser beam cross sections to avoid high peak intensities. Without using a traditional diffraction-grating stretcher, pulse energies of approximately 9 microJ with pulse durations of 280 fs at repetition rates of 200 kHz were generated.     

Directly diode-pumped millijoule subpicosecond Yb:glass regenerative amplifier

An Yb:glass regenerative amplifier directly side pumped by four 20-W diodes is demonstrated. By use of a novel pumping scheme and introduction of cylindrical optics into the cavity, a free-running average output power as great as 4 W with a TEM(00) -like mode was achieved from the bare cavity, with a 0.56 pump duty cycle. When the regenerative amplifier injected, 1-mJ 200-fs FWHM pulses were obtained following compression by use of 2-ms pump pulses and up to a 150-Hz repetition rate.     

Passive Q switching and self-frequency Raman conversion in a diode-pumped Yb:KGd(WO(4))(2) laser

We report on the laser performance of a diode-pumped Yb:KGd(WO(4))(2) laser that is passively Q switched with a Cr(4+):YAG saturable absorber. Raman conversion of fundamental laser emission in the laser crystal was demonstrated. Q-switched 3.4-mu;J pulses with a pulse width of 85 ns were obtained at the 1033-nm fundamental wavelength and 0.4-mu;J pulses with a pulse width of 20 ns were produced in a first Stokes at 1139 nm.     

Microjoule pulses from a passively mode-locked Yb:KY(WO(4))(2) thin-disk oscillator with cavity dumping

We demonstrate, for the first time to our knowledge, a passively mode-locked femtosecond thin-disk oscillator with cavity dumping. A beta-barium-borate-based pockels cell imposes cavity dumping at a repetition rate of 1 MHz. The laser generates pulse energies up to 3 microJ with a pulse duration of 680 fs in a diffraction-limited beam.     

High-peak-power pulses from a cavity-dumped Yb:KY(WO4)2 oscillator

We report generation of 1.35 microJ femtosecond laser pulses with a peak power of 3 MW at 1 MHz repetition rate from a diode-pumped Yb:KY(WO4)2 laser oscillator with cavity dumping. By extracavity compression with a large-mode-area fiber and a prism sequence, we generate ultrashort pulses with a duration of 21 fs and a peak power of 13 MW.     

240-fs pulses with 22-W average power from a mode-locked thin-disk Yb:KY(WO(4))(2) laser

We demonstrate what is to our knowledge the first passively mode-locked thin-disk Yb:KY(WO(4))(2) laser. The laser produces pulses of 240-fs duration with an average power of 22 W at a center wavelength of 1028 nm. At a pulse repetition rate of 25 MHz, the pulse energy is 0.9microJ , and the peak power is as high as 3.3 MW. The beam quality is very close to the diffraction limit, with M(2)=1.1 .     

Thin-disk Yb:KLu(WO(4))(2) laser with single-pass pumping

Single-pass pumping of a thin disk consisting of an only 50 microm thick epitaxial layer of 32 at.% Yb-doped KLu(WO(4))(2) grown on a 0.35 mm thick undoped KLu(WO(4))(2) substrate is demonstrated. The thin-disk laser delivered 9 W of continuous wave output power near 1030 nm with a slope efficiency of 77%.     

新型激光晶体Yb:KY(WO4)2的结构与光谱

采用顶部籽晶提拉法,以K2W2O7为助溶剂,生长了Yb:KY(WO4)2新型激光晶体.经热重-差热分析,确定晶体熔点为1045℃,相变温度为1010℃.X射线粉末衍射测试,验证所生长的晶体为β-Yb:KY(WO4)2.晶体结构分析确定Yb:KY(WO4)2晶体由WO6八面体连接而成,WO6八面体是由双氧桥(WOOW)及单氧桥(WOW)构成.晶体粉末样品室温下的红外及拉曼光谱测试,确定WO6原子基团、双氧桥及单氧桥的振动频率.晶体的吸收峰位于940nm,980nm,发射峰位于989nm-1030nm.     

Yb3+:KY(WO4)2 laser with a fast saturable absorber

Quantum-well semiconductor structures with superlattice barriers and reduced recovery time of absorption are designed and manufactured. A saturable absorption mirror based on such a structure is used in the Yb³⁺:KY(WO₄)₂ laser. The mode locking at a repetition rate of 70 MHz yields an almost bandwidth-limited pulse with a duration of about 115 fs. The maximum mean power (1.57 W) is comparable with a CW power of 1.62 W, which indicates a relatively low level of nonsaturable loss in the saturable absorption mirror.     

Highly efficient 1 GHz repetition-frequency femtosecond Yb3+:KY(WO4)2 laser

We present a highly efficient, diode-pumped, femtosecond Yb3+:KY(WO4)2 (Yb:KYW) laser operating at a 1.024 GHz repetition rate. The output was centered at a wavelength of 1042 nm and had a bandwidth of 3.8 nm, leading to transform-limited pulses with durations of 278 fs determined by fringe-resolved autocorrelation measurements. The optical-to-optical conversion efficiency and slope efficiency were 61% and 69%, respectively, and the relative intensity noise was <0.1%.     

Er/Yb∶KY(WO_4)_2晶体的各向吸收光谱和上转换发光特性

测试了Er/Yb∶KY(WO4)2晶体在室温下3个轴Ng,Np,Nm方向上的吸收光谱,分析比较光谱特性,并计算出各能级跃迁的吸收截面,其中沿Np轴方向有最强的吸收和较大的吸收截面,这有利于激光上能级的粒子数堆积,增大跃迁几率,加强荧光输出。由于掺入Yb3+离子,晶体在980 nm附近有很强的吸收和较大的半峰宽。该晶体在980 nm激光泵浦下有上转换绿光和红光,3个晶轴Np,Ng,Nm轴方向的上转换荧光,波峰位置相差甚微,强弱区别明显,且呈现的各向异性,其中Np方向最强。     

Diode-pumped femtosecond Yb:KGd(WO(4))(2) laser with 1.1-W average power

We demonstrate what is to our knowledge the first mode-locked Yb:KGd(WO(4))(2) laser. Using a semiconductor saturable-absorber mirror for passive mode locking, we obtain pulses of 176-fs duration with an average power of 1.1 W and a peak power of 64 kW at a center wavelength of 1037 nm. We achieve pulses as short as 112 fs at a lower output power. The laser is based on a standard delta cavity and pumped by two high-brightness laser diodes, making the whole system very simple and compact. Tuning the laser by means of a knife-edge results in mode-locked pulses within a wavelength range from 1032 to 1054 nm. In cw operation, we achieve output powers as high as 1.3 W.     

Yb-doped KY(WO4)2 planar waveguide laser

High-quality monoclinic KY(WO4)2 optical waveguides were grown by liquid-phase epitaxy, and laser operation of an Yb-doped KY(WO4)2 waveguide was demonstrated for the first time to our knowledge. Continuous-wave laser emission near 1 microm was achieved with both surface and buried planar waveguides. An output power of 290 mW was obtained in the fundamental mode and the slope efficiency was above 80%.     

Nonlinear refractive properties of Yb3+-doped KY(WO4)2 and YVO4 laser crystals

The nonlinear refractive indices of Yb³⁺: KY(WO₄)₂ and Yb³⁺:YVO₄ laser crystals are characterized using a Z-scan technique at a wavelength of 1.08 μm for different polarizations. The results reveal that the nonlinear refractive index of Yb³⁺:YVO₄ is superior to that of Yb³⁺:KY(WO₄)₂ and is found to be 1.9×10^-15 cm²/W and 1.5×10^-15 cm²/W for E⊥c and E∥c polarizations, respectively. PACS 42.65.Hw; 42.55.Rz; 42.65.Re; 42.70.Hj