RESUMEN
A high power single-frequency operation at 1112â nm with novel insertable monolithic planar ring oscillator based on a Nd:YAG/YAG bonded crystal is proposed. In a proof-of-principle experiment, a finely designed coating on the output surface is carried out to ensure single-wavelength oscillation at 1112â nm, together with a half-wave plate and a Tb3Ga5O12 crystal inserted in the open space of the bonded block to realize the unidirectional operation with power scalability. Consequently, the single-frequency laser delivers an output power of 3.9 W at 1112.3â nm with a slope efficiency of 58.6% and an optical-to-optical efficiency of 17.7%. The power fluctuation is measured to be within ± 0.26% over 20 min, and the laser linewidth is estimated to be 4.15â MHz (Δλ = 0.017 pm).
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The geometric aberration of centered refracting double-plane symmetric optical systems (DPSOS) is investigated. For DPSOS with different defocus values in the tangential plane and the sagittal plane (astigmatic wavefront), a pair of curved reference surfaces which vanishes the quadratic terms of the optical path difference (OPD) between a general ray and a reference ray are deduced. With the curved reference surfaces, the primary (fourth-order) wave aberration function for DPSOS is calculated and analyzed, which can be used for beam shaping designs with astigmatic input wavefront, such as slab lasers and semiconductor lasers. Further, the proposed curved reference surfaces can be applied to analyze the aberrations of general DPSOS.
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A compact and robust all-solid-state mid-infrared (MIR) laser at 6.45 µm with high average output power and near-Gaussian beam quality is demonstrated. A maximum output power of 1.53 W with a pulse width of approximately 42â ns at 10 kHz is achieved using a ZnGeP2 (ZGP) optical parametric oscillator (OPO). This is the highest average power at 6.45 µm of any all-solid-state laser to the best of our knowledge. The average beam quality factor is measured to be M2 = 1.19. Moreover, high output power stability is confirmed, with a power fluctuation of less than 1.35% rms over 2 h, and the laser can run efficiently for more than 500 h in total. Using this 6.45 µm pulse as a radiation source, ablation of animal brain tissue is tested. Furthermore, the collateral damage effect is theoretically analyzed for the first time, to the best of our knowledge, and the results indicate that this MIR laser has excellent ablation ability, making it a potential replacement for free electron lasers.
Asunto(s)
Láseres de Estado Sólido , Animales , LuzRESUMEN
An integrated aberration-compensating module (IACM), consisting mainly of an adjustable slab-aberration compensator, a one-dimensional Shack-Hartmann wavefront sensor, and a data processor, which meet the urgent requirements of correcting the specific wavefront aberrations of a slab laser based on an off-axis stable-unstable resonator, is designed and experimentally demonstrated. Benefits include compactness, robustness, simplicity, automation, and cost-effectiveness. The particular wavefront aberrations of the 9 kW level quasi-continuous-wave Nd:YAG slab laser, which have characteristics of asymmetry, large amplitude and gradient, high spatial frequency, and low temporal frequency, were measured and theoretically analyzed. In the experiment, the wavefront aberrations of the slab laser were corrected by the IACM. At the average output power of 9 kW, the diffraction-limited factor ß was improved from 20.3 times diffraction limit (DL) to 3.6 times DL. The peak-to-valley and root-mean-square values of aberrations were reduced from 9.6 to 0.85 µm and from 2.86 to 0.18 µm within five iterations of the IACM, respectively. Moreover, The IACM is capable of maintaining the compensating surface figure after power-off.
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We present a kilowatt-level quasi-continuous-wave (QCW) cryogenically cooled 946-nm slab laser oscillator for the first time, to the best of our knowledge. The laser system is based on a double-face-pumped large-size single-slab Nd:YAG design, delivering a record-high average power of 1.06 kW without additional amplification. This laser oscillator operates at repetition rate of 400 Hz with a pulse duration of 175 µs, resulting in a single pulse energy of 2.65 J. To the best of our knowledge, these results represent the highest output power and pulse energy for any all-solid-state 946-nm laser ever reported to date. Our scheme paves a new path for the development of the compact high-power solid-state 946-nm laser.
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For reshaping aperture size and correcting low-order aberration of laser beams with large aspect ratios, a simplified analytical method is proposed to design an anamorphic refractive shaping system, which is composed of double-plane symmetric lenses. The simplified method enables performing a global study of aberrations via calculating the analytical primary wave aberration function under paraxial approximation. The aberration balance is analyzed with a three-lens laser collimating system and a compact four-lens laser expanding system. Lens bending and conic surfaces are introduced to decrease ray errors. Through the simplified analytical method, anamorphic refractive shaping systems for laser beams with large aspect ratios can be adequately analyzed and conveniently designed.
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A 100 W level kilohertz repetition-rate microsecond (µs)-pulse all-solid-state sodium beacon laser at 589 nm is demonstrated for the first time, to the best of our knowledge, via combining two independent µs-pulsed lasers. Each beamlet is generated by the sum-frequency mixing of pulsed 1064 and 1319 nm lasers in a lithium triborate (LBO) crystal, which operate at 500 Hz pulse repetition frequency with 61 W $p$p-polarized and 53 W $s$s-polarized output, respectively. An incoherent sequence combining technology of polarized laser beams is employed to add the two beamlets. The average power of the combined beam is up to 107.5 W with a combining efficiency of 94.3%. The combined beam has a 1 kHz repetition rate with ${\sim}{120}\;\unicode{x00B5} {\rm s}$â¼120µs pulse duration and beam quality ${M^2} = {1.41}$M2=1.41. The central wavelength with a linewidth of ${\sim}{0.3}\;{\rm GHz}$â¼0.3GHz is locked to a sodium ${{\rm D}_{2a}}$D2a absorption line. To the best of our knowledge, this is a record-high power operating at kilohertz for µs-pulsed solid-state sodium beacon lasers.
RESUMEN
The polychromatic laser guide star (PLGS) is one of the solutions proposed to measure the differential atmospheric tip-tilt. A watts-level microsecond pulse all solid state laser source with two wavelengths at 589 and 819.7 nm are developed to perform a proof-of-concept on-sky test for what is believed to be the first time. By sum-frequency of 1319 and 1064 nm, a 44 W maximum average output power at 589.159 nm is generated with the pulse width of ~90 µs at 500 Hz, the linewidth of 0.46 pm, and the beam quality of M2 = 1.50. Meanwhile, a 2.4 W average output power is achieved operating at 819.710 nm with the pulse width of ~25 µs at 500 Hz, the linewidth of 0.8 pm, and beam quality factor of M2 = 1.20, which is end-pumped by a frequency-doubled 1064 nm Nd:YAG laser. Moreover, double resonant fluorescence in sodium cell with two step excitation of sodium atom from 3S1/2 to 3D5/2 via 3P3/2 level is observed clearly by tuning the wavelength of 589 and 819.7 nm beams. In the proof-of-principle experiment, it is preliminarily verified that this laser system is expected to be applied to the sky experiment.
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We report a compact, long nanosecond (ns) pulse duration stretched laser source by a multi-pass cavity (MPC). Based on the combination of the MPC and pump power, a high-power high beam quality 1064 nm Q-switched Nd:YAG laser with a pulse duration adjustable over the range of 160-1000 ns was obtained at a pulse repetition frequency of 10 kHz for the first time, to the best of our knowledge. At a typical pulse width of 560 ns, an average output power of 10.6 W was successfully achieved. The beam quality factor M2 was measured to be 1.45 with a good Gaussian mode.
RESUMEN
Slab gain media with large aspect ratios were difficult to be adopted in ultrafast regenerative amplifiers (RAs) due to the obstacle of mode matching with the seed beam. We proposed that an unstable cavity could be employed to solve this difficulty by taking the advantage of its large fundamental mode volume. In this way, an Nd:YVO4 slab-based picosecond RA has been successfully demonstrated using a stable-unstable hybrid cavity. The maximum average output power of 10.5 W was achieved at the repetition rate of 10 kHz. The beam quality factor M2 was measured to be 1.54 in the stable direction and 2.26 in the unstable direction.
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We have proposed a novel approach to realize a high-energy ultrafast optical parametric oscillator (OPO) by intracavity pumping in a regenerative amplifier. In this way, we have experimentally demonstrated an unprecedented pulse energy of 30.5 µJ from a 1.5-µm singly resonant synchronously pumped OPO at a pulse repetition rate of 10 kHz with a pulse width of 7.0 ps. To the best of our knowledge, this is the highest pulse energy from an ultrafast laser OPO.
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We report a high-energy single-frequency deep-ultraviolet (DUV) solid-state laser at 167.079 nm by the eighth-harmonic generation of a diode-pumped Nd:LGGG laser. A maximum DUV laser output energy of 1.5 µJ at a 5 Hz repetition rate with a 200 µs pulse duration is achieved. The central wavelength of the DUV laser is located at 167.079 nm and can be finely tuned from 167.075 to 167.083 nm. The linewidth is estimated to be 0.025 pm. To the best of our knowledge, this is the first Letter reporting a high-energy single-frequency solid-state DUV laser below 170 nm. The successful demonstration of the high-energy single-frequency DUV laser source with the unique wavelength is useful for direct detection of a Al+27 ion via resonance fluorescence in a multi-ion optical clock.
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A picosecond (ps) mid-infrared (MIR) optical parametric amplifier (OPA) with LiInSe2 crystal was demonstrated for the first time. The MIR OPA was pumped by a 30 ps 1064 nm Nd:YAG laser and injected by a barium boron oxide (BBO)-based widely tunable near-infrared seed. A maximum idler pulse energy of 433 µJ at 4 µm has been obtained under a pump energy of 17 mJ, and the corresponding pulse duration was estimated to be ~13 ps. To our knowledge, this is the highest single pulse energy generated by LiInSe2 crystal. Furthermore, an idler spectrum tuning from 3.6 to 4.8 µm was investigated at fixed pump energy of 15 mJ.
RESUMEN
A pulse width adjustable 1064 nm Q-switched cavity dumped Nd:YVO4 laser was realized for the first time, to the best of our knowledge, by rotating an intracavity quarter-wave plate (QWP) and a Pockels cell (PC). The pulse width adjustment range was 4.8-7.8 ns with a constant output power of 3.6 W, and it reached 4.8-13.5 ns for a lower output power of 1.3 W. The pulse width was dependent mostly on the rotating angle of the QWP and PC, but independent of the gain and pulse repetition rate.
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A 65 W quasi-continuous-wave microsecond-pulse solid-state sodium beacon laser tuned to the sodium D2a line has been developed with a linewidth of 0.3 GHz, beam quality of M2=1.38, and pulse width of 120 µs at a repetition rate of 500 Hz by sum-frequency mixing 1319 and 1064 nm diode-pumped Nd:YAG master-oscillator power-amplifier systems. The laser wavelength stability is less than ±0.15 GHz through feedback controlling. The laser spiking due to relaxation oscillations is suppressed by inserting frequency doublers in both 1319 and 1064 nm oscillators. Sodium D2b re-pumping is accomplished by tuning the frequency of the electro-optic modulator with the right D2a-D2b offset. A bright sodium laser guide star with a photon return of 1820 photons/cm2/s was achieved with the laser system when a 32 W circular polarized beam was projected to the sky during our field test at the Xinglong Observatory.
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We demonstrate a sub-pm linewidth acousto-optic (AO) Q-switched nanosecond Nd:GYSGG ring laser at 1336.6 nm side-pumped by 808-nm quasi-continuous wave (QCW) diode lasers for the first time. With incident pulse energy of 4.23 J at 10 Hz, a maximum output macropulse energy of 36.7 mJ at 1336.6 nm with linewidth of less than 0.85 pm and a micropulse width of 300 ns was obtained at a repetition rate of 80 Hz, corresponding to an average micropulse peak power of 15.3 kW. The M² factors were measured to be 1.42 and 1.10 in x and y directions, respectively. It can be tuned from 1336.576 to 1336.652 nm with a tuning resolution of 1 pm. The 1336.632 nm can be converted to deep ultraviolet (DUV) laser at 167.079 nm through its eighth harmonics, which is very useful for the ²7Al⺠optical frequency standard.
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We demonstrate a ps 167.75-nm vacuum-ultraviolet (VUV) laser by cascaded second-harmonic generation (SHG). The VUV laser is produced by eighth-harmonic generation (EHG) of a mode-locked ps 1342-nm Nd:YVO4 amplifier through three stages cascaded SHG with two LiB3O5 crystals and one KBe2BO3F2 crystal, successively. The 167.75-nm laser provides up to 65-µW output power, and the corresponding photon flux and photon flux density are 5.5×10(13) s(-1) and 1.6×10(18) s(-1)·cm(-2), respectively.
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A low-timing-jitter high-power semiconductor saturable absorber mirror mode-locked picosecond (ps) 1063 nm Nd:GdVO4 master oscillator power amplifier is presented. Using a single-pass Nd:GdVO4 amplifier, an amplified laser with 21.5 W output power and 8.3 ps pulsewidth was achieved at 250 MHz repetition rate. Employing a servo control, an average RMS timing jitter of â¼222 fs was realized. This laser can be used as a drive laser for photocathode injectors in free-electron lasers.
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A high average power 1342 nm passively CW mode-locked picoseconds (ps) composite Nd:YVO4 laser was demonstrated with a semiconductor saturable absorber mirror (SESAM). The oscillator cavity was carefully designed to optimize the laser beam radii in the crystal and on the SESAM. The combination of composite bonded laser crystal, direct pumping, and dual end-pumped configuration was adopted to reduce the thermal effect and produce high output power with high beam quality. A maximum average output power of 7.63 W was obtained with a repetition rate of 77 MHz and a pulse duration of 24.2 ps under an absorbed pump power of 38.6 W, corresponding to an optical-optical efficiency of 19.7% and a slope efficiency of 25.9%, respectively. The beam quality factor M(2) was measured to be 1.49.
RESUMEN
An 8 kW level quasi-continuous-wave (QCW) face-pumped 1064 nm slab laser with high beam quality was developed by a master oscillator power amplifier (MOPA) system. A single-mode fiber seed laser was amplified by two-stage single-pass Nd:YAG rod preamplifiers and four face-pumped Nd:YAG slab amplifiers. The slab amplifiers were well designed with uniform pumping and uniform cooling for well-distributed thermal and stress. A dynamically feedbacked optical aberration compensation device was employed to correct low-order optical aberration, and the residue high-order optical aberration was corrected by an adaptive optics system. The QCW MOPA delivered up to an average power of 8.2 kW with a pulse duration of 200 µs at a repetition rate of 400 Hz. The beam quality factor was measured to be ß=3.5.