Warsaw University of Poland successfully developed high-efficiency ultraviolet femtosecond pulsed laser

[China Instrument Network Instrument Development] Recently, the University of Warsaw, Poland successfully developed a micro-wavelength femtosecond pulse laser, its efficiency is three times higher than the original equipment, but its shape is only the size of the fingertips.

Although advanced laser technology has been able to cover a wider spectral region, laser light of about 300 nm in the ultraviolet range is still difficult to achieve, and in particular it is even more difficult to manufacture high-strength short-pulsed ultraviolet lasers. In general, scientists convert near-infrared laser pulses into ultraviolet laser pulses through a non-linear frequency converter. However, the adjustment of the inverter is extremely complicated, and its conversion efficiency is only about 10%.

Researchers at the University of Warsaw in Poland have developed a miniature tripler with a conversion efficiency of more than 30%, and a single-beam laser is focused by a cascaded second-order frequency multiplier to generate a 246 fs UV pulse. Through the three-dimensional modeling of the propagation process of the focused broadband light field in nonlinear and birefringent media, the design of this ultra-compact high-efficiency frequency converter can be realized.

The researchers developed an open source simulation software called “Hussar” that allows users with no design experience to perform accurate 3D simulations of the propagation of multiple laser pulses.

Tomasz Kardas, a developer of simulation software, said: “Once we define input pulse parameters such as pulse energy, duration, and spatial beam profile, the software can search for optimal nonlinear crystal thickness, beam size, beam waist position, etc. To our surprise, we constructed the laser according to the design criteria searched by the software and measured its performance, and the UV pulse measured according to the experiment was almost the same as the simulation result.The degree of agreement between the experimental and simulation results was in nonlinear optics. It is quite rare."

Increasing the efficiency of triple frequency to more than 30% is only the first step in the study. Researchers are trying to shrink the size of the device. The frequency triplers currently used are not a single component, but are still built from the many components in the lab.

Pawel Wnuk, one of the designers of the frequency triplers, said: "Actually, the one-inch-size metal support in all components is the largest part of the whole device. Therefore, the total volume of the tripler prototype is smaller than ever before. The design is 1,000 times smaller."

The study was published in the "Scientific Report."

(Original Title: Development of High-Efficiency Ultraviolet Femtosecond Pulsed Laser at Warsaw University)