a, Fluorescence spectrum of Y-cut Yb:LCB at room temperature. b, Laser spectrum with totally different phonon quantity n = 1 ~ 5. c, Laser output energy versus the absorbed pump energy for varied phonon numbers.
CHINA, October 19, 2023 /EINPresswire.com/ — The direct lasing exterior the fluorescence spectrum is deemed unattainable owing to the ‘zero-gain’ cross-section. Nevertheless, when electron-phonon coupling meets laser oscillation, an power modulation by the quantized phonon would occur, thus immediately creating some unprecedented lasers with extended wavelengths by phonon engineering. Right here, we reveal the multiphonon-assisted lasing in a Yb:La2CaB10O19 crystal, far beyond its spontaneous fluorescence spectrum. This work offers new alternatives to go looking for on-demand lasers in the darkness.
Electron and phonon are two basic particles (quasi-particles) of condensed matter and their interaction in single crystals can create many fascinating bodily phenomena, reminiscent of polariton, cost density wave, up-conversion fluorescence, and so on. In laser crystal, the digital transitions of energetic ion will be manipulated by its surrounding lattice vibrations, thereby the emitting photon power step by step decreases or will increase by the creation or annihilation of quantized phonon. Due to this fact, some broadband laser wavelengths will be designed by the selective amplification of phonon-assisted emission, together with Ti:Sapphire, alexandrite, Cr:LiSAF, and so forth. Nevertheless, all these laser wavelengths nonetheless find inside the spontaneous fluorescence spectrum, or barely exterior with a number of nanometers.
In multiphonon-assisted emission, the creation of high-order phonons can cut back photon power step-by-step, thus pushing laser wavelengths far beyond the spontaneous fluorescence spectrum. Just lately, Liang et. al. demonstrated such a multiphonon-assisted lasing in Yb:YCa4O(BO3)3 (Yb:YCOB) crystal with phonon quantity n = 3~8, which attributed to constructive interactions of vibrational modes from “free-oxygen” websites. Nevertheless, borates containing “free-oxygen” are very uncommon, lower than one p.c of the whole rare-earth borates, thereby giving a limitation for looking extra strong-coupling laser supplies. Due to this fact, looking new structural motif in rare-earth borates could be very important to elaborate the physics mechanism of multiphonon coupling lasing, and likewise discover their distinctive functions in our life.
Yb-doped La2CaB10O19 (Yb:LCB) crystal is a multi-functional laser crystal invented by Prof. Yicheng Wu in 1998. Right here, the authors current a broadband laser emission in Yb:LCB crystal beyond its fluorescence spectrum. The electron-phonon coupling depth is calculated by Huang-Rhys S issue and the phonon-assisted fluorescence lineshape is predicted numerically. A broadband lasing emission spectrum (1000-1280 nm) is obtained by amplifying the weak multiphonon-assisted transitions step-by-step with rising phonon numbers n=1 ~ 6. Theoretical calculations present that such a considerable lasing spectrum is dedicated to multiphonon coupling at a dangling “quasi-free-oxygen” website, as demonstrated by the in-situ Raman experiment.
The potential of Cheng and colleagues’ work doesn’t finish there. “Yb:LCB is a non-centrosymmetric crystal, it’s potential to make a multidisciplinary coupling between multiphonon-coupled lasing and frequency-doubling, thus making a self-frequency doubling laser with the extended wavelengths in the seen vary or self-OPO laser in mid-infrared vary.” they added.
“This multiphonon coupling laser represents a major step ahead for broadband tunable sources and supplies a flexible route for many functions, e.g. ultrafast laser, frequency-comb, laser show and dermatology. This might be a milestone work in solid-state laser engineering, as the invention of ruby and Ti:sapphire.” the scientists forecast.
Funding data
This work was supported by the Nationwide Key Analysis and Improvement Program of China below Grant Nos. 2021YFB3601504 and 2021YFA0717800; the Nationwide Pure Science Basis of China below Grant Nos. 52025021, 92163207, 51890862, 51890863, and 52002220.
DOI
10.1038/s41377-023-01243-x
Unique Supply URL
https://doi.org/10.1038/s41377-023-01243-x
Lucy Wang
BioDesign Analysis
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