Blue laser plays a key role in laser display, printing, manufacturing, data records and medical technology.Collagen quantum dots (QDS) are materials for the growth of solution. They have a strong and adjustable launch and cover the entire visible spectrum. However, the current technically feasible blue QD laser has not yet been realized, and most of them depend on cadmium -containing red QDS.In response to this problem, Researcher Wu Kaifeng and Associate Professor Yang Yang of the Dalian Institute of Chinese Academy of Sciences propose a ZNSE -ZNS nuclear shell quantum dot solution to achieve spontaneous radiation (ASE) and laser launch, showing about 1.2NSs dual-stimulus life and 0.8ns double-stimulus gain life, which is equivalent to the advanced CDSE base complicated nuclear shell system with a diameter of 10-20 nm and emitting red light. Its compact size and long -gain life make these blue quantum dots use like laser dyes.Through femtosecond and nanoseconds, the strong blue ASE can be observed, and the narrow line width (& lt; 0.2 nm) that can output adjustable can be output.The work is published in "Nature NanoteChnology" in "Blue Lasers users of Low-Toxicity Colloidal Quantum Dots".
Design and representation
ZNSE-ZNS nuclear shell quantum quantum quantum quantumPoints (QDS) are prepared by improved synthesis methods, with zinc gluttered stone crystal structures, and the average diameter of the nuclear shells is about 3.50 nm and 7.82 nm, respectively.For typical I -type nuclear shell quantitative points, optical gain is mainly contributed by the core area. Therefore, using relative thin -shell samples can achieve a large gain coefficient.However, the laser laser laser laser at compact quantum dots is usually affected by the rapid non -radiation Auger composite.The work uses high -temperature shell coating conditions to accelerate the diffusion of the ucchic ions, and forms an interface alloy ZNSE1−XSX to smooth the original steep restricted potential and inhibit Auger composite.In the end, the composition of the ZNSE -ZNS nuclear shell quantum dot was actually ZNSE -ZNSE1−XSX -Zns.ZNSE -ZNS quantum dot absorption and optical glow (PL) spectrum display. After coating, the first excitement peak was moved from 397 nm to 412 nm.The PL band -border peak is about 420 nm, the narrow full width half height (FWHM) is about 14 nm, and the quantum yield is about 50%.Time distinguish the PL measurement and display the dual index attenuation, the time constant is 6.3 ns (63%) and 21 ns (37%).
Figure 1: ZNSE-ZNS quantum dot representation
Flying transient stateAbsorption and optical gainFigure 2 indicates that under the low pump energy 11.7 μJ CM−2, it is mainly based on the 412 nm excitement.1shh/LH -1SE jump state filling.Under the high pump energy 2744 μJ CM−2, the spectrum displays multiple early lighting features, indicating the sequence filling of the stimulating state.After many agonum attenuation, the TA spectrum finally returned to the spectrum of low excitement.Figure 2C shows TA dynamics counted by different excitement at 412 NM.With the increase of the number of excitement, the amplitude of rapid attenuation ingredients also increases.Through the TA with the number of high -tight ta dynamics from the tainer, the life span of the double excitement is 1.2 NS.
As the number of inspiration increases, the non -linear absorption spectrum A ′ eventually becomes negative in the long wavelength area and achieves optical gain.The number of gain thresholds appears at about one average excitement, indicating that gain is dominated by double excitement gain.In the larger stimulus, optical gain covered 390-440 nm.Compared with the cross -section of the cross -absorbing cross -section with the steady -state point, when the number of excitement is 12.8, the gain section (σg) at 422 nm and 404 nm is five times larger than the early CDSE quantum dot.
Figure 2: ZNSE-ZNS quantum dot femtosecond-state absorption and optical gain
Sap Radiation Enhancement
Use strip laser beam to stimulate the solution. Wide spontaneous radiation is observed under low pump energy.At the time of the value, the state of spontaneous radiation enhancement (ASE) is transformed, and the threshold is about 1.7, which is consistent with the dual -tone gain mechanism.In addition, a high -energy ASE peak at 404 NM is related to high -energy gain features.The long -gain life (τg = 812 PS) of the quantum dot indicates that there is no need for femtosecond to excite the pulse. Under the stimulation of nanoseconds, the emission of the quantum dot solution also shows sharp aSE from wide spontaneous radiation to 423 nm.The relationship between the launch strength and the energy of the pump shows the ASE threshold of about 3 mJ CM−2. The modal gain coefficient is 53 CM−1, which is far greater than the liquid optical scattering loss.In the case of femtosecond and nanoseconds, the ASE of the quantum dot solution shows strong directionability.
Figure 3: ZNSE-ZNS quantum dot-dot solution excited (ASE)
Adjustable liquid laser laser transmission
In order to achieve laser oscillation, the feedback required to provide multiple gains with the cavity is required to generateA narrower and adjustable spectral output.To this end, a lith -configuration cavity is designed, including high reflective silver mirrors and grating.By adjusting the light grille angle, the blue laser adjustment range is 417 nm-424 nm, and the line width is only 0.2 nm. In contrast, the spontaneous glow and the ASE line width are wider.In the beam contour and directional measurement, the laser beam shows the symmetrical Gaussian strength contour, and the beam radius shows expansion at different distances.The transmission factor of laser is higher than single -mode laser because of multi -mode.The time coherent of the time of the Laser Laser with the Michael Sun Interference Instrument is related to the high time.In addition, the ZNSE -ZNS quantum dot has high working stability, the laser strength is almost no attenuation within 6 hours, and it shows the "light increase" effect.
Figure 4: Under the stimulation of nano, the adjustable liquid laser laser of the littrow cavity
Figure 5: Laser direction, relatedness, polarization and stability
Summary
The work uses ZNSE -ZNS core shell quantum dot solution with compact size and enhancement of inhibitory characteristics to achieve blue spontaneous radiation enhancement (ASE) and laser emission.Its significant laser stability makes the ZNSE -ZNS quantum dot solution become a promising solution in the technology of liquid optical gain medium and other traditional laser dyes or CDSE quantum dots that cannot be applied.In addition, using ZNSEXS1−X nuclear, it is expected to extend the wavelength of liquid quantum dot laser to the ultraviolet region.
Full text Link: https://doi.org/10.1038/s41565-024-01812-0
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