GdCOB Laser Research Articles

Self-frequency-doubling Yb:GdCOB laser intracavity-pumped Pr:YAP laser

Abstract We present for the first time a Pr:YAlO3 (Pr:YAP) laser emitting at 547 nm intracavity-pumped by a self-frequency-doubling Yb3+:Ca4GdO (BO3)3 (Yb:GdCOB) blue laser at 488 nm. We carried out a model to design the system properly, and the laser performance was experimentally investigated. Intracavity sum-frequency mixing at 547 and 488 nm was then realized in a CsLiB6O10 (CLBO) nonlinear crystal to reach the ultraviolet laser at 258 nm. We obtained a continuous wave output power of 575 mW at 258 nm with a pump source, which is a diode-pumped quasi-three-level Sr1-x La x -y Nd y Mg x Al12-x O19 (Nd:ASL) laser emitting 11.2 W at 902 nm.

Quasi-three-level laser pumped Yb:GdCOB tunable laser from 1030 to 1036 nm

We report a quasi-three-level laser pumped Ca4GdO(BO3)3 (Yb:GdCOB) tunable laser based on the transition from the 2 F 5/2 level to the 2 F 7/2 level. By adjusting the 902 nm pump power, a continuous waves Yb:GdCOB laser was obtained with the near-infrared wavelengths shifting from 1030 nm to 1036 nm. The highest tuning power of 2.5 W was achieved with a slope efficiency of 19.9%. To our knowledge, it is the first tunable Yb:GdCOB laser to be realized by adjusting the pump power. This work provides a novel method to generate tunable solid-state lasers with a compact and simple structure.

Tunable continuous-wave Yb: GdCOB laser with an electro-optic crystal

We present a diode-pumped tunable continuous wave (CW) Yb:Ca4GdO(BO3)3 (Yb:GdCOB) laser using an electro-optic crystal based on the 2 F 5/2−2 F 7/2 transition. The highest output power of 3.21 W was achieved at an emission wavelength of 1030 nm with a slope efficiency of 27.2% with respect to the absorbed pump power. Combined with polarization components Yb:GdCOB, the electro-optical crystal KH2PO4 (KDP) formed a Lyot filter in the cavity and compressed the available gain bandwidth. With an adjustable voltage applied to the KDP crystal, the laser wavelength could be tuned from 1024 to 1034 nm. To our knowledge, it is the first study that has realized the tuning in Yb:GdCOB laser.

17.9 W continuous-wave self-frequency-doubled Nd:GdCOB laser

We demonstrated the output power scaling of a self-frequency-doubled (SFD) laser with N d : G d C a 4 O ( B O 3 ) 3 (Nd:GdCOB) crystal by employing a partially end-pumped slab structure and optimized laser-diode (LD) pump wavelength. Associated with the theoretical calculation about the thermal distribution in the SFD Nd:GdCOB crystal, the maximum SFD output power was achieved to be 17.91 W at the wavelength of 545.5 nm, which represents the highest output power in SFD lasers, and the optical conversion efficiency from the LD to SFD laser power reached up to 20%. Since the wavelength at 545.5 nm is located at the eye-sensitive spectral region and the SFD lasers have the advantages in the compact structure, the demonstrated SFD laser should have promising applications in some regimes such as laser display, medical, military, and scientific research.

Thermo-optic dispersion formulas for YCOB and GdCOB laser host crystals

We report on a comparative study of anisotropy and dispersion of thermo-optic coefficients, dn/dT, and thermal coefficients of the optical path for monoclinic oxoborate YCOB and GdCOB laser host crystals. Near 1 μm, all dn/dT coefficients are found to be negative: dnX/dT = –1.2, dnY/dT = –3.7 and dnZ/dT = –2.5 × 10−6 K−1 for YCOB, dnX/dT = –3.8, dnY/dT = –4.8 and dnZ/dT = –3.7 × 10−6 K−1 for GdCOB. Thermo-optic dispersion formulas are derived for these crystals in the spectral range of 0.4–2 μm. The existence of athermal directions is predicted for both YCOB and GdCOB.

Efficient high-power self-frequency-doubling Nd:GdCOB laser at 545 and 530 nm

We report an efficient high-power self-frequency-doubling (SFD) Nd:GdCOB laser. The maximum output power is 3.01 W at a wavelength of 545 nm with an optical efficiency of 20.7%, which, to our knowledge, is the highest SFD laser output power and efficiency yet obtained. By optimizing the configuration and cut orientation of the Nd:GdCOB crystals, a SFD laser at a wavelength of about 530 nm was achieved with a maximum output power of 1.32 W. We propose that these SFD lasers will have promise in applications such as laser displays, medical treatment, spectroscopic analysis, etc.

Passively <bold>Q</bold>-switched self-frequency-doubling <inline-formula><math display="inline" overflow="scroll"><msup><mi>Nd</mi><mrow><mi>3+</mi></mrow></msup><msub><mi>:GdCa</mi><mrow><mstyle mathvariant="normal"><mtext>4</mtext></mstyle></mrow></msub><msub><mi>O(BO</mi><mrow><mstyle mathvariant="normal"><mtext>3</mtext></mstyle></mrow></msub><msub><mstyle mathvariant="normal"><mtext>)</mtext></mstyle><mrow><mstyle mathvariant="normal"><mtext>3</mtext></mstyle></mrow></msub></math></inline-formula> laser with GaAs saturable absorber

Nd 3 + :GdCa 4 O(BO 3 ) 3 , i.e., Nd:GdCOB, is a new self-frequency-doubling laser crystal. By using a GaAs saturable absorber as a passive Q-switched, the Q-switched Nd:GdCOB laser at 0.53 μm is successfully realized. Meanwhile, the pulse width and the single pulse energy are measured and the numerical solutions of the coupling wave rate equations are in agreement with the experimental results.

High-power diode-pumped Yb:GdCOB laser: from continuous-wave to femtosecond regime

We present an efficient tunable continuous-wave diode-pumped Yb 3+ :Ca 4 GdO(BO 3 ) 3 (Yb:GdCOB) laser producing at room temperature up to 3.2 W average power with a slope efficiency of 80% when pumped with a 10 W laser diode. A large tunability from 1017 to 1086 nm is obtained. The broad emission spectrum has been used to develop a diode-pumped Yb:GdCOB femtosecond laser. The laser generated 90 fs pulses, at a center wavelength of 1045 nm. By using a semiconductor saturable absorber mirror (SESAM) for the mode locking, the average power was 40 mW and the repetition rate of 100 MHz.

Passively Q-switched self-frequency-doubled Nd^3+:GdCa_4O(BO_3)_3 laser

The performance of a flash-lamp-pumped self-frequency-doubled Nd3+:GdCa4O(BO3)3 (Nd:GdCOB) laser that is passively Q switched with Cr4+:YAG saturable absorbers is demonstrated. The maximum 0.53-µm pulse energy obtained is 2.6 mJ, and the maximum peak intensity is 15 MW/cm2. The dependence of the pulse characteristics on the orientation of the saturable absorber and on the cavity length is measured. Meanwhile, the transversal distribution of the intracavity photon density is taken into account in the rate equations for an intracavity frequency-doubled passively Q-switched laser, and the solutions are used to account for the behavior of the passively Q-switched Nd:GdCOB laser.

Multiwatt, tunable, diode-pumped CW Yb:GdCOB laser

We demonstrate that Yb-doped Ca4GdO(BO3)3 (GdCOB) crystals are suitable for the development of high-power diode-pumped lasers emitting at around 1.04 μm. A 15%-doped Yb:GdCOB crystal was longitudinally pumped with a cw fiber-coupled diode emitting 10 W at 976 nm. While 5.2 W of diode power was absorbed, we obtained 3.2 W of 1043-μm laser light, with a beam quality factor M2 equal to 3, and 2.5 W in a diffraction-limited beam. Furthermore, the laser is continuously tunable between 1018 and 1086 nm. Thermal effects have been investigated with a Shack–Hartmann wavefront analyser: although thermal lensing is not negligible, it does not affect the performance of the laser with the resonator design we used.

Efficient self-frequency doubling of Nd:GdCOB crystal by type-I phase matching out of its principal planes

We report on the efficient self-frequency doubling of Nd:GdCOB crystal by type-I phase-matching at θ=66.3° and ϕ=134.4°, which is out of its principal planes. A CW output power of 225 mW at 530.5 nm is obtained at an absorbed pump power of 1.56 W with an optical conversion efficiency of 14.4% and an absorbed threshold pump power of 1.8 mW. To our knowledge, this is the highest output power, the highest efficiency and the lowest threshold obtained from a self-frequency-doubled Nd:GdCOB laser to date.

Efficient and tunable continuous-wave diode-pumped Yb^3+:Ca_4GdO(BO_3)_3 laser

A Yb(3+):Ca(4)GdO(BO(3))(3) (Yb:GdCOB) crystal has been diode pumped for the first time to our knowledge. We obtained 47.5% slope efficiency at 6 degrees C, producing 191 mW of power at 1050 nm, with a 2.4% output coupler. Temperature does not significantly affect the laser performance: At room temperature we still obtained 180 mW of power for the same cavity. We achieved tunability of the Yb:GdCOB laser from 1035 to 1088 nm with a 1.7% output coupler and 100-nm tunability with a low-transmission output coupling (T = 0.03%).

Infrared laser performance and self-frequency doubling of Nd 3+:Ca 4GdO(BO 3) 3 (Nd:GdCOB)

Gadolinium calcium oxoborate, Ca 4GdO(BO 3) 3 (GdCOB), is an efficient nonlinear borate crystal presenting suitable sites for activator ions. Nd 3+ doped GdCOB has been investigated as a new laser crystal in order to develop a self-frequency doubling material. Large and good optical quality crystals of Nd:GdCOB have been grown from the melt. Nd 3+ optical properties were studied via Judd-Ofelt analysis. Nd 3+ polarized absorption and emission cross sections were measured at room temperature. Stark levels of Nd 3+ 4L j manifolds in GdCOB are given. Nd:GdCOB laser has been demonstrated, with a cw Ti:sapphire pump source, for several Nd 3+ concentrations. The crystal was shown to lase along its three crystallophysic axes. The best slope efficiency is 45 % for the fundamental laser output at 1.060 μm. According to the infrared laser output polarization, configuration of Nd:GdCOB crystals, for type I self-frequency doubling in ZX and XY principal planes, were investigated. A 0.530 μm green laser was observed by self-frequency doubling. Linear and nonlinear optical properties of Nd:GdCOB are compared to those of NYAB in the prospect of self-frequency doubling applications.