High-peak-power narrowband eye-safe intracavity Raman laser

High average power and high repetition rate eye-safe Raman laser driven by a two-crystal Nd:YVO4 laser

We report on a high average power and high repetition rate nanosecond pulsed eye-safe KGW Raman laser intracavity driven by an acousto-optic Q-switched 1342 nm two-crystal Nd:YVO4 laser. Taking advantages of the carefully selected two-composite-laser-crystal configuration, the thoroughly optimized gate-open time of acousto-optic modulator and the ingeniously designed U-shaped resonator, substantial power and efficiency enhancements as well as superior mode matching have been enabled. Under the injected pump power of 64.5 W, the average output powers of the first-Stokes fields at 1496 and 1527 nm can be up to 8.1 and 9.5 W with 25 kHz repetition rate and 3.2 µs gate-open time, respectively, corresponding to the optical power conversion efficiencies of 12.6% and 14.7%. Meantime, the resultant pulse widths are determined to be 4.6 and 6.3 ns with the peak powers of approximately 70 and 60 kW, respectively. The beam quality can be maintained with M2 < 1.5 across the entire output power range.

Ten-watt-level all-solid-state eye-safe intracavity Raman laser

We demonstrate the first ten-watt-level eye-safe intracavity crystalline Raman laser, to the best of our knowledge. The efficient high-power eye-safe Raman laser is intracavity-pumped by an acousto-optically Q-switched 1314 nm two-crystal Nd:YLF laser. Benefiting from the unique bi-axial properties of KGW crystal, two sets of eye-safe dual-wavelength Raman lasers operating at 1461, 1645 nm and 1490, 1721nm are achieved by rotating the Raman crystal. Under the launched pump power of 84.9 W and the repetition rate of 4 kHz, the maximum first-Stokes output powers of 7.9 W at 1461 nm and 8.2 W at 1490 nm are acquired with the second-Stokes output powers of 1.4 W at 1645 nm and 1.5 W at 1721nm, respectively, leading to the eye-safe dual-wavelength Raman output powers of up to 9.3 and 9.7 W. Meanwhile, the pulse durations at the wavelengths of 1461, 1490, 1645, 1721nm are determined to be 4.8, 5.5, 4.3, and 3.6 ns, respectively, which give rise to the peak powers approaching about 410, 370, 80, 100 kW. These Stokes emissions are found to be near diffraction limited with M2 < 1.6 across the entire output power range.

High-repetition-rate and high-beam-quality all-solid-state nanosecond pulsed deep-red Raman laser

We report on a high-repetition-rate and high-beam-quality all-solid-state nanosecond pulsed deep-red laser source by intracavity second harmonic generation of the actively Q-switched Nd:YVO4/KGW Raman laser. The polarization of the 1342 nm fundamental laser was aligned with the Ng and Nm axes of KGW crystal for accessing the eye-safe Raman lasers at 1496 and 1526 nm, respectively. With the aid of the elaborately designed V-shaped resonator and the composite Nd:YVO4 crystal, excellent mode matching and good thermal diffusion have been confirmed. Under an optimal pulse repetition frequency of 25 kHz, the average output powers of the Raman lasers at 1496 and 1526 nm were measured to be 3.7 and 4.9 W with the superior beam quality factor of M2 = 1.2, respectively. Subsequently, by incorporating a bismuth borate (BIBO) crystal, the deep-red laser source was able to lase separately two different spectral lines at 748 and 763 nm, yielding the maximum average output powers of 2.5 and 3.2 W with the pulse durations of 15.6 and 11.3 ns, respectively. The resulting beam quality was determined to be near-diffraction-limited with M2 = 1.28.

High-power diode-end-pumped 1314 nm laser based on the multi-segmented Nd:YLF crystal

We demonstrate the first multi-segmented Nd:YLF laser, to the best of our knowledge. The multi-segmented crystal was designed to straightforwardly aim for the minimum thermal stress without sacrificing the overall laser efficiency, with the influence of the pump beam waist position considered in particular. Integrating the enhanced thermo-mechanical resistance of multi-segmented crystal and the alleviated heat load of low quantum defect pumping, this end-pumped 1314 nm Nd:YLF laser system delivered a maximum continuous-wave output power of up to 35.5 W under a pump power of 105 W, corresponding to an optical-to-optical efficiency of 33.8%. Furthermore, by incorporating an acousto-optic modulator, an active Q-switching oscillator was accomplished, yielding a maximum average output power of 22.9 W at a pulse repetition frequency (PRF) of 20 kHz and a largest pulse energy of 13.6 mJ at a PRF of 1 kHz.

High-performance diode-end-pumped Nd:YLF laser operating at 1314 nm

A stable, efficient, and powerful 1314 nm Nd:YLF laser inband-pumped by a wavelength-locked narrowband 880 nm laser diode is demonstrated. The influence of mode-to-pump ratio on the performance of the diode-end-pumped Nd:YLF laser has been systematically investigated by taking into account the thermal effect and the energy transfer upconversion effect. For the optimum mode-to-pump ratio of 0.84, the maximum continuous wave output power of 21.9 W was extracted under the pump power of 70 W, which corresponded to the optical power efficiency of 31.3% and the beam quality of M² ≈ 1.6. The resultant output power stability was determined to be 0.059% (RMS) within 1 h. In addition, by increasing the mode-to-pump ratio to 1.0, the near-diffraction-limited beam (M² ≈ 1.3) was achieved with the output power of 17.0 W and the optical power efficiency of 24.3%.

Intra-cavity diamond Raman laser at 1634 nm

We demonstrated an eye-safe diamond Raman laser intra-cavity pumped by the 1.3 μm fundamental field for the first time, to the best of our knowledge. The first-Stokes laser at 1634 nm was converted from the 1342 nm fundamental laser, which was produced by an in-band pumped double-end diffusion-bonded a-cut Nd:YVO₄ crystal. Under an incident pump power of 21.2 W and an optimal pulse repetition frequency of 25 kHz, the maximum average output power of 2.0 W was obtained with the pulse duration of 5.7 ns and the peak power of 14 kW. The first-Stokes emission was found to be near diffraction limited (M² ≈ 1.3) and to have a narrow linewidth (∼0.05 nm FWHM; instrument limited).