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Updated: May 10, 2026

Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements
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通过多相相匹配诱导的双层高非线性纤维中的多波长第二和生成

Xiaoyu Chen, Xue Zhou, Xin Yan

    Optics letters
    |June 2, 2024
    PubMed
    概括

    研究人员在光纤中实现了多波长的第二和生成 (SHG),使用了秒激光和合光纤. 这一突破使得定制的超快光源能够用于医疗诊断和光学传感中的应用.

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    相关概念视频

    ¹H NMR: Complex Splitting01:13

    ¹H NMR: Complex Splitting

    A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
    Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
    ¹H NMR: Interpreting Distorted and Overlapping Signals01:02

    ¹H NMR: Interpreting Distorted and Overlapping Signals

    Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
    As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
    Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule01:10

    Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule

    In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1  triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the others.
    ¹³C NMR: ¹H–¹³C Decoupling01:04

    ¹³C NMR: ¹H–¹³C Decoupling

    The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
    A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
    Tandem Mass Spectrometry01:21

    Tandem Mass Spectrometry

    Tandem mass spectrometry is a technique that uses multiple mass analyzers in series to obtain a higher selectivity and reduce chemical noise during analyte detection. Instruments with multiple analyzers separated by an interaction cell enable secondary fragmentation and selected study of the fragment ions.Secondary fragmentations occur in the interaction cell and can be induced by various factors. Fragmentation induced by collision with inert gases, such as N2, Ar, He, etc., is called...
    Double Resonance Techniques: Overview01:12

    Double Resonance Techniques: Overview

    Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
    Spin decoupling is usually achieved by...