A high-brightness ultrabroadband supercontinuum white laser has attracted an increasing number of consideration in physics, chemistry, biology, supplies science, and different disciplines of science and expertise. Over the previous many years, many alternative approaches have been developed for supercontinuum white laser era.

Most of them make the most of varied third-order nonlinear results (Third-NL) like self-phase modulation (SPM) occurring inside microstructured photonic crystal fibers or homogeneous plates, or noble gas-filled hollow-core fibers. Nevertheless, the standard of those supercontinuum sources has been topic to some limitations, comparable to small pulse vitality at nanojoule degree and request of sophisticated dispersion engineering.

One other extra highly effective means to increase the spectral vary of laser is varied second-order nonlinear results (2nd-NL) through the promising route of quasi-phase matching (QPM) scheme. Nevertheless, these purely 2nd-NL schemes are nonetheless poor within the efficiency of spectral and energy scaling due to slim pump bandwidth, restricted QPM working bandwidth, and degraded vitality conversion effectivity in higher-order harmonics.

Frankly talking, it has turn out to be an ideal problem to resolve these dangerous limitations present in each 2nd-NL and Third-NL regimes and make the perfect of each worlds for producing a full-spectrum supercontinuum laser with spectral protection from UV to mid-IR vary.

In a brand new paper printed in Gentle: Science & Functions, a workforce of scientists, led by Professor Zhi-Yuan Li from Faculty of Physics and Optoelectronics, South China College of Expertise, China and colleagues have show an intense four-octave-spanning ultraviolet-visible-infrared (UV-Vis-IR) full-spectrum laser supply (300 nm to 5000 nm at -25 dB from the height) with the vitality of 0.54 mJ per pulse coming from a cascaded structure of gas-filled hollow-core fiber (HCF), a naked lithium niobate (LN) crystal plate, and a specifically designed chirped periodically poled lithium niobate crystal (CPPLN), which is pumped by a 3.9 mm, 3.3 mJ mid-IR pump pulse.

Beneath the pump of a 3.3 mJ 3.9 μm mid-IR femtosecond pulse laser, the HCF-LN system can generate an intense one-octave bandwidth mid-IR laser pulse to function the secondary FW pump enter into the CPPLN, whereas the CPPLN helps high-efficiency broadband HHG processes to additional increase significantly the spectral bandwidth into UV-Vis-NIR. Clearly, this cascaded structure creatively satisfies the 2 preconditions for producing full-spectrum white laser: Situation 1, an intense one-octave pump femtosecond laser, and Situation 2, a nonlinear crystal with extraordinarily giant frequency up-conversion bandwidth. Furthermore, the system entails appreciable synergic motion of 2nd-NL and Third-NL results.

Such a synergy mechanism they developed brings a superior energy to construct a superior enlargement of the general UV-Vis-IR supercontinuum spectrum and filling-in of the spectral gaps amongst varied HHG far exceeding these achieved by single motion of both 2nd-NL or Third-NL results that have been adopted in earlier works.

Consequently, such a cascaded HCF-LN-CPPLN optical module has enabled entry to a beforehand inaccessible degree of an intense full-spectrum laser output, with not solely an especially giant bandwidth (spanning 4 octaves), but additionally high-flatness spectral profile (from 300 to 5000 nm with a flatness higher than 25 dB), and enormous pulse vitality (0.54 mJ per pulse).

“We consider that our scheme to create an intense four-octave-spanning UV-Vis-IR full-spectrum femtosecond laser supply by harnessing the synergic motion of 2nd-NL HHG and Third-NL SPM results represents a giant step for the development of supercontinuum white laser supply with bigger bandwidth, bigger energy vitality, greater spectral brightness, and flatter spectral profile. Such an intense full-spectrum femtosecond laser would supply a revolutionary device for optical spectroscopy and discover potential purposes in physics, chemistry, biology, supplies science, info expertise, industrial processing, and surroundings monitoring,” the scientists says.