Green Laser Output Research Articles

The role of co-dopant Ce3+ on the spectral properties of Dy3+ activated YAG single crystal for yellow green laser application

Ce3+ and Dy3+ co-doped Y3Al5O12 (abbr. as Ce, Dy: YAG) single crystal was grown by the Czochralski method. As compared with the absorption spectrum of Dy: YAG crystal, the synchronous doping of Ce3+ ions into Dy: YAG crystal resulted in a wide excitation band in the 425–500 nm region peaking around 447 nm owing to the 4f→5d transition of Ce3+ ions, and inhomogeneous broadening absorption with the full width at half maximum (FWHM) from 4 nm to 39 nm. Furthermore, due to the efficient energy transfer from Ce3+ to Dy3+ ions in YAG crystal, under 447 nm excitation Ce, Dy: YAG crystal showed intense and wide characteristic yellow green emission, whose intensity increased by 12.3 times and FWHM from 12 nm to 113 nm as compared with Dy: YAG crystal. The fluorescence lifetime of Dy3+: 4F9/2 level has increased from 693.1 μs to 2.062 ms. Based on the above results, Ce, Dy: YAG crystal would be an excellent candidate for the realization of yellow green waveband laser output.

High Repetition Frequency Solid-State Green Laser with Large Stable Area for Water Jet Guided.

This paper presents the design and experimental results of a long cavity length Nd:YAG laser with a large stable zone for water jet-guided laser (WJGL) applications. The design is based on the light transmission matrix and resonator stability conditions, aiming to achieve a large stable zone and a short cut-off thermal focal length (CTFL). A folded concave resonator is researched to enhance the cavity length, and the influence of the tunable cavity arm length on the oscillating beam in the resonator and in the YAG crystal is theoretically studied. Moreover, the effects of the output mirror curvature and the cavity arm length on the range of the stable area and the cut-off thermal focal length are also investigated. Experimental results show that a stable green laser output is obtained after second harmonic generation (SHG) with a pulse width ranging from 43 to 143 ns within the laser operating frequency range of 5-20 kHz. At an operation frequency of 10 kHz, the output power is 21.33 W, and the instability of the output power within 400 min is 0.88%. The laser source achieves a maximum power of 25.7 W at 20 kHz, and the maximum single pulse energy reaches 2.7 mJ at 6 kHz. Finally, this is used as the laser source to couple with a water jet with a diameter of 100 microns, achieving a lossless water conductivity transmission over 60 mm length. These results demonstrate the suitability of the designed laser source for WJGL technology research. In precision machining applications, this technology exhibits processing advantages of low thermal damage (~2 μm) and large depth (>10 mm), for 7075 aluminum alloy.

532 nm pumped visible emission from Ho3+-doped fiber lasers

We report a green fiber laser based on an in-band pumping process for the first time. The impact of the pumping mechanism on output characteristics is addressed, and a new pumping strategy to improve the output performance of visible fiber lasers is presented. We demonstrate the highest power of 0.52 W green fiber laser output using a single-wavelength 532 nm solid-state laser as the pump source, and we also exhibit dual-wavelength excitation with a maximum power output of 0.72 W. Simultaneously, we investigate the reasons of visible dual-wavelength generation and modulation approaches in Ho3+-doped fluoride fibers. This method efficiently tackles the problem of visible light generation in Ho3+-doped fibers being limited, as well as pave the way for more efficient and powerful visible fiber lasers.

Passively Q-switched dual-wavelength green laser with an Yb:YAG/Cr4+:YAG/YAG composite crystal.

A compact dual-wavelength passively Q-switched green laser by intra-cavity frequency doubling of a Yb:YAG/Cr4+:YAG/YAG composite crystal was demonstrated for the first time to our best knowledge. The maximum green laser output power of 1.0 W was obtained under the pump power of 9.7 W, and the corresponding slope efficiency is 15.2%. The shortest pulse width, largest pulse energy, and highest peak power were achieved to be 5.54 ns, 246.1μJ, and 40.76 KW, respectively. Dual-wavelength laser oscillation simultaneously at 515 nm and 524.5 nm has been achieved. This passively Q-switched dual-wavelength green laser can be used as a laser source for Terahertz generation.

RGB and white-emitting organic lasers on flexible glass.

Two formats of multiwavelength red, green and blue (RGB) laser on mechanically-flexible glass are demonstrated. In both cases, three all-organic, vertically-emitting distributed feedback (DFB) lasers are assembled onto a common ultra-thin glass membrane substrate and fully encapsulated by a thin polymer overlayer and an additional 50 µm-thick glass membrane in order to improve the performance. The first device format has the three DFB lasers sitting next to each other on the glass substrate. The DFB lasers are simultaneously excited by a single overlapping optical pump, emitting spatially separated red, green and blue laser output with individual thresholds of, respectively, 28 µJ/cm(2), 11 µJ/cm(2) and 32 µJ/cm(2) (for 5 ns pump pulses). The second device format has the three DFB lasers, respectively the red, green and blue laser, vertically stacked onto the flexible glass. This device format emits a white laser output for an optical pump fluence above 42 µJ/cm(2).

Laser diode and pumped Cr:Yag passively Q-switched yellow-green laser at 543 nm

Efficient and compact yellow green pulsed laser output at 543 nm is generated by frequency doubling of a passively Q-switched end diode-pumped Nd:YVO4 laser at 1086 nm under the condition of sup-pressing the higher gain transition near 1064 nm. With 15 W of diode pump power and the frequency doubling crystal LBO, as high as 1.58 W output power at 543 nm is achieved. The optical to optical conversion efficiency from the corresponding Q-switched fundamental output to the yellow green output is 49%. The peak power of the Q-switched yellow green pulse laser is up to 30 kW with 5 ns pulse duration. The output power stability over 8 hours is better than 2.56% at the maximum output power. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by frequency doubling of a passively Q-switched end diode pumped Nd:YVO4 laser at 1086 nm. DOI: 10.1134/S0030400X13030296

Experimental Study of Nd:YVO<sub>4</sub>/KTP Solid Laser Pumped by Diode Laser

Build a diode laser end-pumped Nd:YVO4/KTP solid laser system, Nd:YVO4 crystal was used as the solid laser medium, it emitting 1064nm infrad laser when it was pumped by 808nm diode laser, then the 1064nm infrad laser was changed to 532nm green laser by frequency doubling with a KTP crystal inside the optical cavity. Based on experiment, the relationship between diode laser power output and diode laser injection current, the relationship between laser pump power and 532nm green laser output, and the other factors possibly affecting 532nm laser output which include KTP phase match angle, pump light focus position and all-solid-state-laser (ASSL) cavity length was also studied. The experimental results show that to increase the output of 532nm green light needs to improve the pump diode laser power, shorten the length of the solid laser cavity , focus the pump laser to the middle of the Nd:YVO4 crystal, and choose correct KTP crystal phase-matching angle.

A Green Upconversion Laser with Erbium-Doped LiLuF<SUB>4</SUB> Crystal by 976 nm Fiber Laser Pump

A stable fiber laser operating at appro ximately 976 n m peak power at a 280 ns and 1.9 W pump was used as a pumping source for an upconversion laser based on an Er 3+ :doped LiLuF4 crystal. A 548 n m wavelength and 320 mW could be achieved. In this study, we used a 976 n m lo w threshold average pump power fiber laser at 8 mW, wh ich can achieve green upconversion laser output at room temperature. Th is system includes a high reflective coating at 552 n m+/-10 n m on the LiLuF4 crystal and a 96% reflective mirror forming a laser cavity fo r the 548 n m laser. Using the laser cavity setup and 976 n m fiber laser pu mp, lo w threshold pump power green erbiu m upconversion lasing was achieved. The two peak wavelengths of 548 n m and 537 n m are observed and the intensity changes by changing the input to 976 n m pu mp power.

Compact 151 W green laser with U-type resonator for prostate surgery

We analyzed, designed and fabricated a U-type resonator for intra-cavity frequency doubling of a diode-side-pumped Q-switched Nd:YAG rod laser with high power and high stability for surgery of prostatic tissue. The resonator stability conditions were analyzed graphically in the various configurations for a U-type resonator. We obtained green light at 532nm using a single KTP crystal, with average output power of 151W at 10kHz repetition rate, and with 113ns pulse duration at 810W input pump power. We achieved 1064–532nm conversion efficiency of 75.8%, and pump-to-green optical–optical efficiency of 18.6%. The green power fluctuation was ±1.0% and pointing stability was better than 4μrad. The green laser output was coupled to a side-firing medical fiber to transfer the laser beam to the prostatic tissue.

Laser-diode pumped CW Nd:GdVO4 green laser with periodically poled KTP

A laser-diode pumped CW Nd:GdVO4 green laser with periodically poled KTP is first reported. The TEM00-mode green laser output power is 1.54 W at 4.44 W incident pump power, corresponding to an optical conversion of 31.5%, which is more than twice of that of the conventional KTP. The predicted results are compared with measured data and good agreement is reported.

110 W high stability green laser using type II phase matching KTiOPO4 (KTP) crystal with boundary temperature control

We have developed a diode-pumped high power and high stability green laser. By controlling and stabilizing the boundary temperature of type II phase matching KTP crystal, 110 W high stability green laser output have been achieved. Temperature distribution inside the KTP crystal has been analyzed by solving the thermal conductivity equation. From the temperature distribution inside the KTP crystal, we have calculated the optimal phase matching angles and temperature bandwidth of the type II KTP crystal as a function of temperature. The second harmonic conversion efficiency as a function of temperature has also been calculated. In the experiment, the type II phase matched KTP crystal (optimum phase matching angles are Φ=24.68°, Θ=90° under the condition of phase matching temperature 353 K) was used in the intrcavity frequency-doubling resonator. An average output power of 110 W at 532 nm has been achieved with values of 11% and 2% for the optical-to-optical conversion efficiency and the instability, respectively. The optimal boundary temperature of the KTP crystal has been found to be 321.8 K. The experiment results are in good agreement with the theoretical calculation.

A diode-pumped linear intracavity frequency doubled Nd:YAG rod laser with [formula omitted] pulse width and [formula omitted] green output power

We analyzed a linear cavity for intracavity frequency doubling of a diode-pumped acousto-optic Q-switched Nd:YAG rod laser, and showed that a green laser beam with a short pulse width can be generated efficiently. A green laser output power of 73 W corresponding to the 83.9% of maximum IR output power was obtained with a 40 ns pulse width at a 10 kHz repetition rate. A green output power of 40 W with a 35 ns pulse width was measured at a 5 kHz repetition rate. Minimum laser pulse width of approximately 32 ns was obtained around 1 kHz repetition rate for both green and IR laser beams.

Characterization of the laser crystal Nd:GdVO_4

Nd:GdVO4 crystal was grown by the Czochralski method. The absorption and fluorescence spectra of the crystal were measured at room temperature. The thermal expansion and the specific heat of the crystal were also measured. Laser outputs at 1.06 and 1.34 µm were achieved when a Nd:GdVO4 crystal sample with a high Nd doping concentration was pumped by a low-power laser diode (LD) at 808.5 nm, and visible green and red laser outputs of intracavity frequency doubling at 0.53 and 0.67 µm were also achieved when nonlinear KTiOPO4 and LiB3O5 crystal, respectively, were used. The highly Nd-doped Nd:GdVO4 crystal was pumped by a high-power LD, and a greater than 5-W laser output power at 1.06 µm was obtained. A low-Nd-doping concentration Nd:GdVO4 crystal sample was pumped by a high-power LD, yielding laser output powers at 1.06 and 0.53 µm; 0.53-µm green laser output was obtained when a KTiOPO4 crystal was used, and the output beam’s values were M2=1.76 at an output power of 14.3 W at 1.06 µm and M2=1.55 at an output power of 3.3 W at 0.53 µm. Acousto-optical Q-switched laser outputs at 1.06 and 0.53 µm were also achieved. A thermal lens made from a Nd:GdVO4 crystal was measured; it was weaker than that of a Nd:YVO4 crystal. Some important material parameters, such as temperature-induced changes in refractive index, material constant, thermal-stress resistance figure of merit, and power per unit length at the stress fracture limit, have been estimated.

Thermal Effect in KTP Crystals During High PowerLaser Operation

We report on the theoretical and experimental studies of the thermaleffect of the KTP crystal during high power operation. From the dependenceof the refractive index temperature coefficients on wavelength, thedependence of the optimum phase-matching angles on temperature is derived.In the experiment, the angle of the frequency-doubled KTP crystal istilted to compensate for the thermal effect and to obtainΔϕ = 0.7° when the green laser output power is 30 W andthe KTP crystal temperature is about 80°C. We obtained thehighest stable output power greater than 40 W with an L-shaped flat-flatintracavity frequency-doubled Nd:YAG laser. The experimental results arevery consistent with the theoretical analysis.

Growth of Yb-doped Ca 4GdO(BO 3) 3 crystals and their spectra and laser properties

In this paper, highly Yb-doped Ca 4GdO(BO 3) 3 (Yb : GdCOB) crystals were grown by the Czochralski method. The absorption and fluorescence spectra were measured. The laser of Yb : GdCOB crystal was demonstrated with different output mirrors when it was pumped by a fiber-coupled laser diode (LD) at the wavelength of 976.4 nm. The lowest pumping threshold was 280 mW, the highest light–light conversion efficiency was 33.8%, and the highest slope efficiency up to 70% was thus calculated from the linear part of the curve. The self-frequency doubling (SFD) green laser output was also observed.

Effect of Strontium Ion on the Growth and Second-HarmonicGeneration Properties of GdCa4O(BO3)3 Crystal

Large sized and optical quality GdCa4O(BO3)3 (GdCOB)crystal with calcium partiallysubstituted by strontium (Sr) ions was grown for the first time.The x-ray powderdiffraction shows that the Sr ion has an effect on the cell parametersof the GdCOBcrystal. Second-harmonic generation (SHG) experiments were performedon theSr:GdCOB and GdCOB crystals along the spatial phase-matching direction. Theresults show that the cw green laser output power is 1.04 Wwhen the laser diodepump power is 10 W in the Nd:YVO4/Sr:GdCOB intracavity laser. Considering theslope efficiency of Nd:YVO4 and the fundamental laser in cavity,the intracavity SHGconversion efficiency of the GdCOB crystal is 21% while it is 24% forthe Sr:GdCOBcrystal, the SHG conversion efficiency is improved by 14%. The effectof the Sr ionson the nonlinearity of the GdCOB crystal is also discussed by using theanion group theory. PACS: 42. 65. Ky, 78. 20. -e, 78. 55. Hx

Second-harmonic generation using an <italic>a</italic> axis <inline-formula><roman>Nd:MgO:LiNbO</roman><sub><roman>3</roman></sub></inline-formula> single crystal fiber with Mg-ion indiffused cladding

We report the implementation of a low-loss core-cladding waveguide structure of an a axis Nd:MgO:LiNbO3 single-crystal fiber with a step refractive index profile and the demonstration of a frequency- doubled laser made from such a cladded crystal fiber. The laser-heated pedestal-grown a axis single-crystal fiber, with an elliptical crosssectional area of 200x 150?m, is further shown with a Mg ion indiffusion process. Electron probe microanalysis is used to measure the Mg ion concentration distribution in the Mg-diffused layer. After several trials, diffusion parameters suitable for achieving a core-cladding waveguide structure with a step refractive index profile are obtained. The optical and structural properties of the cladded crystal fibers are also characterized. Room-temperature second-harmonic generation with such a cladded crystal fiber is demonstrated. At room temperature, cw green laser output with a power of 10 ?W at the wavelength of 0.532 ?m is achieved. The origin of the relatively low conversion efficiency is discussed.

Growth of lowly Nd doped GdVO4 single crystal and its laser properties

In this paper, low concentration Nd-doped GdVO4 was successfully grown by the Czochralski method. The laser outputs up to 14.25W at 1.06μm was obtained with a 3mm×3mm×4mm Nd:GdVO4 crystal sample when it was pumped by a cw fiber-coupled laser diode (LD). The doubling green laser output power up to 3.3 W at 0.53μm was also achieved with a 3mm×3mm×4mm Nd:GdVO4 crystal sample and a 3mm×3mm×11mm KTiOPO4 (KTP) crystal sample when pumped by the same LD. Some properties of the Nd:GdVO4 crystal are compared with that of the Nd:YVO4 crystal.

Efficient continuous-wave self-frequency-doubling green diode-pumped Yb:YAl_3(BO_3)_4 lasers

Efficient cw self-frequency-doubled green laser output of 160 mW has been obtained from Yb:YAl(3)(BO(3))(4) crystal pumped by 1.4-W incident power from a fiber-coupled 976-nm laser diode. The incident-pump-power-green-output-power conversion efficiency is greater than 11.3%, and the electrical-input-green conversion efficiency is 3.9%. Tunable green output from 513.0 to 545.8 nm is also demonstrated with a quartz birefringent filter.

Growth and second-harmonic-generation of Bi 3+- or Li +-doped GdCa 4O(BO 3) 3 crystals

The bismuth and lithium cations doped GdGa 4O(BO 3) 3 (GdCOB) crystals were successfully grown for the first time. The X-ray powder diffraction (XRPD) shows that the cell parameters of the doped crystals are slightly larger than that of GdCOB. Intracavity second-harmonic-generation (SHG) experiments were carried out on 3×3×6 mm 3 GdCOB and doped GdCOB crystals along the phase-matching (PM) direction (θ =66.8°, φ =132.6°) . The results show that the continuous wavelength (cw) green laser output power is 0.94 W for GdCOB crystals at 10 W LD pump power while it is 1 W and 1.02 W for the bismuth and lithium doped GdCOB crystals, respectively. Considering the fundamental laser power in the cavity, the intracavity SHG conversion efficiency of GdCOB and bismuth, lithium cations doped GdCOB crystals are 21, 22.6 and 23%, respectively. The SHG conversion efficiency is improved by 8 and 10% when GdCOB is doped with bismuth and lithium cations. The effects of the doped cations on growth and SHG properties of GdCOB crystal are discussed.