The high-brightness ultra-wideband super-continuous white laser is attracting more and more attention in physics, chemistry, biology, materials science and other scientific and technological disciplines. In the past years, many different approaches have been developed to produce a super-continuous white laser.

Most use various third-order nonlinear (3rd-NL) effects, such as self-phase modulation (SPM), which occurs in microstructured photonic crystal fibers or homogeneous sheets or inert gas-filled hollow fibers. However, the quality of these supercontinuity sources is subject to certain limitations, such as low pulse energy at the nanojoule level and the necessity of complex dispersion techniques.

A more powerful way to expand the spectral range of a laser is with various second-order nonlinear (2nd-NL) effects using a promising half-phase matching (QPM) scheme. However, these purely 2nd NL circuits still have poor spectral and power scaling performance due to narrow pump bandwidth, limited QPM operating bandwidth, and low high-order harmonic energy conversion efficiency.

Frankly, it was a huge challenge to get the best of both worlds to overcome these nasty limitations inherent in the 2nd-NL and 3rd-NL modes and produce a full-spectrum supercontinuous laser with UV to medium spectral coverage. -IR range.

In a recent article published by Light: Science and ApplicationsA team of scientists led by Professor Zhi-Yuan Li from the South China University of Technology (China) School of Physics and Optoelectronics and colleagues demonstrated an intense four-octave emitted ultraviolet, visible, infrared (UV-visible-IR) full light wave. – spectrum laser source (300 nm to 5000 nm at -25 dB peak) with 0.54 mJ energy per pulse from the cascade architecture of gas-filled hollow core fiber (HCF), a bare lithium niobate (LN) crystal sheet and 3, Specially designed periodic lithium niobate crystal poles (CPPLN) pumped with a 9 mm and 3.3 mJ medium IR pump pulse.

Pumped with a 3.3 mJ 3.9 μm mid IR femtosecond pulsed laser, the HCF-LN system can generate an intense single octave mid IR laser pulse that acts as the secondary FW pumping input to the CPPLN, while the CPPLN supports high frequencies. Efficient broadband HHG processes for even more significant broadening of the spectral band in UV-Vis-NIR. Obviously, this stepped architecture creatively satisfies two prerequisites for producing a full-spectrum white laser: Case 1, a dense octave-pumped femtosecond laser, and Case 2, a nonlinear crystal with extremely large support bandwidth. Provides a significant synergistic effect of the effects of .NL and 3. NL.

Such a synergistic mechanism they developed provides remarkable power to create a remarkable broadening in the total spectrum of the UV-Vis-IR supercontinuum and fill the spectral gaps between the various HHGs far beyond what can be achieved with a single action. 2. NL or 3. -NL effects adopted in previous studies.

As a result, such a stepped HCF-LN-CPPLN optical module provided access to a previously unattainable level of intense full-spectrum laser radiation, not only with an extremely large bandwidth (covering 4 octaves), but also with high spectral uniformity. profile (300 to 5000 nm, uniformity better than 25 dB) and high impact energy (0.54 mJ per pulse).

“We believe our plan to create an intense femtosecond full-spectrum UV-VIS laser source with a four octave range by exploiting the synergistic effect of the HHG 2nd-NL and SPM 3rd-NL effects is an important step forward in creating a white laser. It has a higher bandwidth, higher power energy. , a supercontinuity source with higher spectral brightness and flatter spectral profile.Such a dense full-spectrum femtosecond laser will become a revolutionary tool for optical spectroscopy and in physics, chemistry, biology, materials science, information technology, industrial processing and environmental monitoring. will find potential applications in their fields,” say the scientists.