43 W picosecond laser and second-harmonic generation experiment

Combining the advantages of diode-end-pumped Nd: YVO₄ and diode-side-pumped Nd: YAG amplifiers, a high average power and high beam quality picosecond laser is designed. The system delivers a picosecond laser with average power of 43.4 W and good beam quality of M² < 1.7. By focusing the high power picosecond laser in LBO crystal, 532 nm green laser with maximal power of 20.8 W is generated and the conversion efficiency of second-harmonic generation reaches 56.4% when 17.7 W green laser obtained from the fundamental frequency laser with power of 31.4 W and beam quality of M² < 1.25.     

An 8.1 W diode pumped solid-state quasi-continuous-wave yellow laser at 589 nm by intracavity sum-frequency mixing generation

We report an L-shaped symmetrical co-folding-arm plane-plane diode pumped solid-state yellow laser at 589 nm by using intracavity sum-frequency mixing. By carefully designing the cavity and employing various techniques to optimize the laser’s specifications, a quasi-continuous-wave (QCW) free-oscillation yellow laser source, which has an average output power of 8.1 W, a beam quality factor of M² = 2.3, and a repetition rate of 1.1 kHz, is developed. The generation of yellow laser at 589 nm is achieved by intracavity sum-frequency mixing between the laser lines at 1319 nm and 1064 nm of an Nd:YAG laser in a KTP crystal. To the best of our knowledge, the 8.1 W output at 589 nm is higher than any other diode pumped solid-state yellow laser generated by intracavity sum-frequency generation so far.     

Intra-cavity second harmonic generation with Nd:YVO4/BIBO laser at 542 nm

We report, for the first time, an efficient intra-cavity second-harmonic generation (SHG) at 1084 nm in a nonlinear optical crystal, BiB₃O₆(BIBO) at the direction of (θ, ?) = (170.1°, 90°), performed with a LD end-pumped cw Nd:YVO₄ laser. With 590 mW diode pump power, a continuous-wave (cw) SHG output power of 19 mW at 542 nm yellow-green color has been obtained using a 1.5 mm-thick BIBO crystal. The optical conversion efficiency was 3.22%. It was found that the output wavelength could be 532 nm, 537 nm or 542 nm according to regulating the angle of BIBO.     

Intracavity frequency doubling of an active Q-switched Nd:YAG laser with 2.25 W output power at 473 nm

An active Q-switched diode-end-pumped Nd:YAG laser is reported with 2.9 W output power on the ⁴F_3/2 → ⁴I_9/2 transitions at a pump power of 24 W. With intracavity frequency doubling using a 20-mm-long LBO, a maximum blue output power of 2.25 W is achieved at a repetition rate of 23 kHz. The conversion efficiency from the corresponding Q-switched fundamental output to blue output is 96%. The peak power of the Q-switched blue pulse is up to 610 W with 160 ns pulse width. The fluctuation of the blue output power is less than 4.0% at the maximum output power.     

28.4 W 266 nm ultraviolet-beam generation by fourth-harmonic generation of an all-solid-state laser

In this paper, 28.4 W 266 nm ultraviolet-beam generation by fourth-harmonic generation of an all-solid-state laser using a CsLiB₆O₁₀ crystal was reported. A conversion efficiency of 24.7% was obtained.     

Passively Q-switched Nd:YAG pumped UV lasers at 280 and 374 nm

Pulsed UV lasers at the wavelengths of 374 and 280 nm are realized by cascaded second harmonic generation (SHG) and sum frequency generation (SFG) processes using a Nd:YAG laser at 1123 nm. The Nd:YAG laser is longitudinally pumped and passively Q-switched, and it has a high peak power of 3.2 kW. The UV peak powers at 280 and 374 nm are 100 and 310 W, with pulse lengths of 6 and 8 ns, respectively. Spectral broadening of 374 nm laser by stimulated Raman scattering is studied in single mode pure silica core UV fiber. Realizations of UV lasers enabling compact design at 280 and 374 nm wavelengths are demonstrated.     

High power and high beam quality CW green beam generated by diode-side-pumped intracavity frequency doubled Nd:YAG laser

We report a stable high power and high beam quality diode-side-pumped CW green laser from intracavity frequency doubled Nd:YAG laser with LBO crystal. By using a advanced resonator, a large fundamental mode size in the laser crystal and a tight focus in the nonlinear crystal could be obtained simultaneously, which are favorable for high power and high beam quality CW green laser generation. The green laser delivered a maximum 532 nm output power of 40 W. The corresponding optical-to-optical conversion efficiency and electrical-to-optical conversion efficiency were 8.6% and 5.0%, respectively. Under 532 nm output power of 34 W, the beam quality factor was measured to be 1.6.     

Diode-pumped intra-cavity doubled Nd:LuVO4 laser at 458 nm

We have demonstrated a diode-pumped intra-cavity frequency doubling Nd:LuVO₄ laser operating at 916 nm with a Z-folded cavity. A 10-mm long LBO crystal, cut for critical type I phase matching at 912 nm, is used for the experiment. A maximum output power of 330 mW at 458 nm has been achieved at pump power of 22 W. The optical-to-optical conversion efficiency and slope efficiency is 1.5% and 2.3%, respectively. The power instability at the maximum output power in 30 min is better than 3%.     

Intracavity second-harmonic generation of 1.06 μm in GdCa4O(BO3)3 crystals

The characteristics of intracavity second-harmonic generation (SHG) at 1.06 μm in GdCa₄O(BO₃)₃ (GdCOB) crystals cut for different type I phase-matching (PM) directions of (θ,φ)=(66.8°, 132.3°); (19.4°, 0°); (90°, 46°) have been investigated. It was found that the intracavity SHG was significantly efficient in the PM direction of (66.8°, 132.3°), and that the intrinsic lower effective nonlinear coefficient (d_eff) was responsible for the less-efficient SHG in the other two directions. A maximum CW SHG output power of 2.81 W was obtained with an optical conversion efficiency of 18.7%, while the corresponding effective intracavity SHG efficiency was determined to be 41.3%. The intracavity SHG efficiency of GdCOB has been found to reach two-thirds of that obtained with type II phase-matching KTiOPO₄ (KTP). Received: 26 April 2000 / Revised version: 3 July 2000 / Published online: 5 October 2000     

Tunable picosecond UV source at 10 kHz based on an all-solid-state diode-pumped laser system

4 laser. The amplified pulses were frequency-converted in the blue and in the UV by harmonic generation (doubling and tripling) in two lithium triborate (LBO) crystals. Received: 11 March 1997/Accepted: 24 April 1997     

Low threshold, actively Q-switched Nd:YVO4 self-Raman laser and frequency doubled 588 nm yellow laser

We reported an actively Q-switched, intracavity Nd³⁺:YVO₄ self-Raman laser at 1176 nm with low threshold and high efficiency. From the extracavity frequency doubling by use of LBO nonlinear crystal, over 3.5 mW, 588 nm yellow laser is achieved. The maximum Raman laser output at is 182 mW with 1.8 W incident pump power. The threshold is only 370 mW at a pulse repetition frequency of 5 kHz. The optical conversion efficiency from incident to the Raman laser is 10%, and 1.9% from Raman laser to the yellow.     

Generation of subpicosecond vacuum ultraviolet pulses at 126 nm by using harmonics of a subpicosecond Ti:Sapphire laser

Subpicosecond vacuum ultraviolet (VUV) pulses at the wavelength of 126 nm have been generated in rare gases as a result of the 7th harmonic radiation of a subpicosecond Ti:Sapphire laser oscillating at 882 nm. The VUV harmonic intensity was optimized in Xe at the pressure of 1.2 Torr. The behavior of the harmonic emission was qualitatively reproduced by the classical nonlinear optics. The increase of the harmonic intensity was limited by multiphoton ionization of Xe.     

532 nm laser based on V-type doubly resonant intra-cavity frequency-doubling

LD side-pumped dual interconnected V-type quasi-continuous wave green laser has been demonstrated. The two Nd:YAG modules were placed in a plane-concave V-type resonator and a plane-concave straight cavity formed two stable operation beam of the 1064-nm fundamental frequency laser. Through acousto-optic Q-switched and frequency doubling crystal, two double-frequency laser beams arrived at the folded flat mirror, which were unidirectional output by the folded flat mirror at the end. As the pumped current was 50 A, the 532 nm green laser maximum average output power of 206 W at a repetition of 22.4 kHz was achieved with a pulse width of 201 ns and the largest single pulse energy of 9.2 mJ, corresponding to a peak power of 45.8 kW and a double frequency efficiency of 60.2%.     

Generation of high average power, 7.5-fs blue pulses at 5 kHz by adaptive phase control

The spectral width of a 5-kHz Ti:sapphire laser system was broadened by spectral control in a regenerative amplifier consisting of broadband chirped mirrors. The dispersion over the wide spectral range was compensated by a deformable mirror along with a genetic algorithm, resulting in a pulse width of 15 fs. The pulse width is the shortest, to our knowledge, in chirped pulse amplification systems with a regenerative amplifier. The phase distortion of broadband frequency doubling in addition to the Ti:sapphire laser was compensated by using the self-diffraction intensity in sapphire as the feedback signal into the genetic algorithm, resulting in a pulse width of 7.5 fs. The average power of the second harmonic was 1 W with a fundamental input of 7 W.     

Non-critically phase-matched,Ti:Sapphire-pumped picosecond optical parametric oscillator using LiB3O5

We report a new source of high-repetition rate and widely tunable picosecond pulses for the near infrared. A singly resonant, cw, picosecond optical parametric oscillator based on temperature-tuned LiB₃O₅ and synchronously pumped by 1.8 ps pulses from a self-mode-locked Ti:Sapphire laser is demonstrated. The oscillator can provide average output powers of up to 90 mW under non-critical type-I phase matching at a pulse repetition rate of 81 MHz. Without dispersion compensation, transform-limited signal pulses with 720 fs durations have been generated at 1.2 times threshold. With the available mirror set, signal tuning over 1.374–1.530 µm and idler tuning over 1.676–1.828 µm is demonstrated for a range of pump wavelengths and phase-matching temperatures. With additional mirrors, continuous tuning throughout 1–2.7 µm should be readily attainable with a single LiB₃O₅ crystal.     

Ytterbium femtosecond fiber laser without dispersion compensation tunable from 1015 nm to 1050 nm

We report on a widely tunable ytterbium fs-fiber laser without dispersion compensation. The all-normal dispersion laser contains a spectral filter for wavelength tuning and for generating additional amplitude modulation to support the nonlinear polarization evolution as mode-locking mechanism. By tilting the interference filter the center wavelength of the laser can be tuned from 1015 nm to 1050 nm with a pulse energy up to 2.0 nJ. The pulses can be dechirped externally to 108 fs.     

High efficiency second harmonic generation with a low power diode laser

\valunit{8}{mW} ( corrected for the output mirror reflection) of the cw coherent blue light around by frequency doubling of only from a diode laser. With IR power of we reach the doubling efficiency of . The overall conversion efficiency from the electrical power into the blue light is . By the way of careful analysis of the Blue Light Induced IR Absorption (BLIIRA) in the potassium niobate based external doubling cavity we obtain good agreement with the theoretical conversion efficiency. Received: 29 November 1996     

Investigation of intracavity third-harmonic generation at 1.06 μm in YCa4O(BO3)3 crystals

Intracavity sum-frequency mixing of 1.06 μm and 532 nm in YCa₄O(BO₃)₃ (YCOB) crystals cut for different type-I phase-matching directions of (θ,ϕ)=(106°,77.2°), (111°, 79.6°) and (65°, 82.8°) was investigated in a compact diode-end-pumped acousto-optical Q-switched Nd:YVO₄/KTP laser formed with a three-mirror folded resonator. The maximum 355-nm average output power of 124 mW was obtained in the phase-matching direction of (106°, 77.2°) with a pump-to-ultraviolet conversion efficiency of 3.3% at the repetition frequency of 20 kHz. Received: 17 September 2001 / Revised version: 27 November 2001 / Published online: 17 January 2002     

High-Power Diode-Side-Pumped Intracavity-Frequency-Doubled Continuous Wave 532 nm Laser

An efficient and high-power diode-side-pumped cw 532nm green laser based on a V-shaped cavity geometry, and capable of generating 22.7 W green radiation with opticM conversion effciency of 8.31%, has been demonstrated. The laser is operated with rms noise amplitude of less than 1% and with M2-parameter of about 6.45 at the top of the output power. This laser has the potential for scaling to much higher output power.     

Compact efficient diode-pumped Nd:YVO4 Q-switched blue laser with intracavity frequency tripling

We demonstrate a compact efficient diode-pumped acousto-optically Q-switched intracavity-frequency-tripled Nd:YVO₄ blue laser. The optimum polarization state is experimentally investigated to optimize the output performance. Greater than 280 mW of 447-nm average power at a repetition rate of 25 kHz was generated with a 15-W diode pump power. At 25 kHz, the pulse width is shorter than 15 ns and the peak power is higher than 800 W.