Dual-wavelength operation of a c-cut Nd:YVO laser at 1062.7/1066.6 nm was demonstrated by using a birefringent filter. The laser was pumped by a home-built Ti:sapphire laser operating at 808 nm. The maximum continuous-wave output power of 300 mW for 800 mW of pump power was obtained. This corresponded to 39% of optical-to-optical efficiency. The proposed design is also suitable for diode-pumping.
Efficient multi-watt operation of a diode-pumped Yb:YLF laser at room temperature was demonstrated. In continuous-wave regime the laser produced up to 8.4 W of average power with ⪆74% of slope efficiency with respect to the absorbed pump power. The laser output had diffraction limited beam quality and its wavelength was tunable over 40 nm. To the best of our knowledge, this is the highest output power for diode-pumped room-temperature Yb:YLF lasers.
We demonstrated continuous-wave dual-wavelength operation of a Yb:YAP laser with intracavity birefringent element. The laser produced a wide range of wavelength pairs with spectral separation from 1 nm up to 35 nm. The average output power reached up to 800 mW. Dual-wavelength radiation was generated owing to the broad gain bandwidth of the Yb:YAP crystal and custom design of a birefringent filter.
Diode-pumped efficient continuous-wave Yb:LLF (Yb:LiLuF4) laser was demonstrated with output power in the multiwatt range. The laser operated in the fundamental mode and produced up to 7.7 W of output power. The laser showed record high 64% of optical-to-optical efficiency and up to 73% slope efficiency with respect to the absorbed pump power. Laser wavelength tuning range was found to be >40 nm around the central wavelength of 1053 nm.
Dual-wavelength operation of a Nd:YVO laser based on two-crystal geometry with the a- and c-cuts was demonstrated. The laser delivered continuous-wave radiation at 1064.4 nm and 1066.6 nm with more than 450 mW of output power. Optical-to-optical efficiency reached more than 50%. The proposed design is suitable for diode-pumping and can lead to compact and efficient dual-wavelength lasers.
Dual-wavelength operation of a diode-pumped Yb:YAP laser using a 1 mm-thick birefringent filter was demonstrated. Multiple wavelength pairs with wavelength separation ranging from 1.8 nm up to 11.3 nm could be generated. The gain balancing for oscillating wavelength pairs was based on the differential loss around a single transmission peak of the filter. In this regime of operation, separation of the wavelength pairs was not limited to the free-spectral range of the filter. This laser can be used to generate THz radiation using a photomixing technique.
We demonstrated continuous-wave dual-wavelength operation of a Nd:CALGO laser with intracavity conerefringent element. The laser produced conically refracted dual-wavelength radiation output with more than 100 mW of power. Dual-wavelength radiation was generated owing to the broad gain bandwidth of the Nd:CALGO crystal.
Efficient diode-pumped continuous-wave Yb:CaF2 laser was demonstrated with multi-watt output power at room temperature. The laser produced up to 9.6 W of output power in the fundamental mode with 64% of optical-to-optical efficiency and up to 71% slope efficiency with respect to the absorbed pump power. Wavelength tuning range was measured to be 60 nm (1011-1071 nm). To the best of our knowledge these are the highest efficiency factors for directly diode-pumped Yb:CaF2 lasers.
Dual-wavelength (DW) operation of Yb:KGW laser was demonstrated by using a 1 mm-thick birefringent filter (BRF). Based on gain balancing around a single transmission peak of the filter, DW pairs with wavelength separation far smaller than the free spectral range of the filter could be generated. A series of DW pairs with wavelength separation of around 0.5 nm (Δν≈0.14 THz) and 4 nm (Δν≈1.1 THz) within the available gain bandwidth were generated. This method can be also applied with the other lasers that have broad gain bandwidth.
A high power conical refraction (CR) laser was demonstrated based on Yb:CALGO laser crystal with a separate intracavity CR element. The CR laser delivered the maximum output power of 6.25 W at 25 W of incident pump power which is the highest output power for the CR lasers to date. The separation of the CR element from the laser gain medium reduced the complexity of laser pumping. The generated CR laser beam exhibited excellent quality with well-resolved concentric rings and the Poggendorff dark ring.
A continuous-wave dual-wavelength Yb:CALGO laser has been demonstrated using a 12-mm thick off-surface axis birefringent filter. The obtained wavelength spacing could be tuned from a few nm up to tens of nm. In the experiments ~7.5 W of output power was obtained for 25 W of the incident pump power.
High power performance of diode-pumped Yb:YAP lasers with different crystal orientation (cuts) was investigated. The crystal samples exhibited similar pump absorption properties. In continuous-wave (CW) regime, the maximum output power of <7 W could be generated using the b-cut and c-cut Yb:YAP crystals with slope efficiency up to 70%, while the laser with the a-cut crystal was limited to 5.6 W of output power most likely due to the thermal lensing effect. Owing to the high thermal conductivity and broad emission bandwidth of Yb:YAP, this crystal is a suitable laser host for high power laser operation in CW and pulsed regimes.
The thermal lensing effect in the Ng-cut Yb:KGW and a-cut Yb:CALGO laser crystals was evaluated and compared using a similar laser cavity and pumping scheme. The Yb:KGW crystal exhibited large anisotropy along the horizontal and vertical axes and the thermal lensing sensitivity factors of Mx=0.52 m-1/W (||Np) and My=0.18 m-1/W (||Nm) were determined. The Yb:CALGO crystal exhibited negligible anisotropy in the thermal lensing power, and thermal lensing sensitivity factors of Mx=0.452 m-1/W (⊥c) and My=0.458 m-1/W (||c) were measured.
A simplified design approach for a hard-aperture Kerr-lens mode-locked Ti:sapphire oscillator was proposed. The technique is based on a simple cavity design and the position of the laser crystal with respect to the cavity mode waist which ensures an enhanced Kerr sensitivity of the oscillator. Experimental results were demonstrated and compared to the numerical calculations. Such a technique can be used and for other laser hosts.
High power performance of a continuous-wave Yb:YAP laser was investigated. The laser generated <7 W of output power with 22 W of pump power and slope efficiency of around 70% while maintaining high beam quality. The thermal lensing effect was observed at high pumping power. The combination of high thermal conductivity and broad gain bandwidth make this laser host a suitable candidate for high power CW and ultrashort pulse generation.
We demonstrated continuous-wave dual-wavelength (DW) operation of a Nd:CALGO laser using a single birefringent filter (BRF) plate. Owing to a new mechanism of the BRF loss action, the equal lasing thresholds at two wavelengths could be provided by a single transmission peak of the filter and wavelength separation was not limited to the free-spectral range (FSR) of the filter. A wide range of DW pairs with wavelength separation from sub-nm up to ~4 nm with adjustable spectral intensity ratio was experimentally demonstrated using a single 2 mm-thick BRF plate.
A conical refraction (CR) laser based on a separate gain medium (Nd:YVO4) and an intracavity CR element (KGW) was demonstrated. The decoupling of the gain and CR media enabled the laser to produce a well-behaved CR laser beam with excellent quality, while reducing the complexity of the pumping scheme. The proposed laser setup has the potential for power scaling using the efficient diode pumping approach and the properties of the generated CR beam are independent from the laser gain medium.
A high-power diode-pumped pure Kerr-lens mode-locked Yb:KGW laser was demonstrated. The developed laser delivered 240 fs pulses with 2.3 W of average output power at a repetition rate of 86.8 MHz. Shorter pulses of around 120 fs with 1.2 W of average output power were also generated. The self-starting operation of the oscillator was demonstrated. The limiting factor to the laser operation was the appearance of a strong continuous wave component in the mode-locked laser spectrum.
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