Yb KGW Laser Crystal

Polarized-a-absorption-spectra-and-b-emission-spectra-along-the-refractive-index-principal-axis-of-Yb-KGW-crystal

Feature

1. The width of absorption line is wide, and the pump wavelength of LD pump source with phase matching can be obtained without strict temperature control;
2. The quantum defect is low, and the pump wavelength is very close to the laser output wavelength, which will lead to a large intrinsic laser slope efficiency, and the quantum efficiency is up to about 90% theoretically;
3. Because the pumped energy level is close to the upper laser level, the thermal load in the material without radiation relaxation is low, which is only one third of that of the same laser material doped with neodymium;
4. No excitation state absorption and upconversion, high light conversion efficiency;
5. Long fluorescence life, more than three times that of the same neodymium-doped laser material, is conducive to energy storage;

Application

1064nm

femtosecond Yb:KGW laser applicated in nonlinear microscopy

Yb-ion based femtosecond lasers operating around 1000 nm are particularly suited for biological imaging with high-resolution multiphoton excitation fluorescence, and third and second harmonic generation microscopy. They are a good alternative to commonly used Ti:sapphire lasers emitting in the 800 nm wavelength regime. Longer excitation wavelengths are desirable due to lower scattering and higher penetration depths in the biological tissue. In addition, the autofluorescence and bleaching are also largely reduced. Furthermore, the generated third and second harmonics fall into the visible range (rather than UV), resulting in higher throughput and a simpler detection scheme. On the other hand, wavelengths in the range of a Cr:forsterite laser at around 1200-1300 nm suffer from significant water absorption. At higher excitation powers that may cause photo-damage of biological tissues. Moreover, direct diode pumping of Yb-ion doped laser gain media considerably reduces the cost of a system in comparison to Ti:sapphire and Cr:forsterite lasers, which are usually pumped by expensive solid-state or fiber lasers.

Yb:KGW oscillators

The extended cavity oscillators offer straightforward approach towards the scaling of the peak power by lowering the repetition rate (typically below 30-40 MHz).Nonetheless, the increased influence of the nonlinear effects usually results in a trade-off between the pulse duration and the peak power (or pulse energy). So far, pulses with 2.3 MW peak power (1 μJ energy) have been delivered from a 10 MHz Yb:KYW bulk oscillator. The pulse duration, however, was limited to 430 fs. Similarly, pulses with 1.3 MW peak power and 323 fs duration were generated from a 23.7 MHz Yb:CALGO bulk oscillator. On the other hand, short pulses with 145 fs duration but at a reduced peak power of 0.16 MW (24 nJ energy) were demonstrated directly from a 27 MHz Yb:CALGO bulk oscillator. Recently we demonstrated 67 fs pulses with 3 W of average output power at a repetition rate of 77 MHz from an Yb:KGW bulk oscillator.

regenerative amplifiers

Watt-level high-repetition-rate Yb:KGW regenerative amplifiers use acousto-optic switching. The obtained pulse energies up to now are on the order of tens of microjoules.