Survey and Countermeasures on Current Situation of Life Education for College Students in Local Normal Colleges and Universities

Life education is the precondition of all education.This paper explored the current situation of life education for college students in local normal colleges and universities through questionnaire survey,and traced the history of life education in the world and China.Combined with history and reality,it analyzed the current problems of life education for college students mainly in three aspects,namely,the lack of connectivity in the educational process,the excessive productization of education,and the fragmentation of life education.Finally,it came up with pertinent recommendations in line with these problems.

A Stable, Wideband Tunable, Near Transform-Limited, Graphene- Mode-Locked, Ultrafast Laser

We report an ultrafast laser mode-locked with a graphene saturable absorber.The linear dispersions of the Dirac electrons in graphene enable wideband tunability.We get-1 ps pulses,tunable between 1525 and 1559 nm,with stable mode-locking,insensitive to environmental perturbations.

Graphene-carbon nanotube hybrid films for high- performance flexible photodetectors

Graphene is being actively explored as a candidate material for flexible and stretchable devices. However, the development of graphene-based flexible photonic devices, i.e. photodetectors, is hindered by the low absorbance of the single layer of carbon atoms. Recently, van der Waals bonded carbon nanotube and graphene hybrid films have demonstrated excellent photoresponsivity, and the use of vein-like carbon nanotube networks resulted in significantly higher mechanical strength. Here, we report for the first time, a flexible photodetector with a high photoresponsivity of - 51 A/W and a fast response time of - 40 ms over the visible range, revealing the unique potential of this emerging all-carbon hybrid films for flexible devices. In addition, the device exhibits good robustness against repetitive bending, suggesting its applicability in large-area matrix-array flexible photodetectors.

Progress on mid-IR graphene photonics and biochemical applications

Mid-infrared （mid-IR） （2-20 μm） photonics has numerous chemical and biologic ＂fingerprint＂ sensing applications due to characteristic vibrational transitions of molecules in the mid-IR spectral region. Unfortunately, compared to visible light and telecommunication band wavelengths, photonic devices and applications have been difficult to develop at mid-IR wavelengths because of the intrinsic limitation of conventional materials. Breaking a new ground in the mid-IR science and technology calls for revolutionary materials. Graphene, a single atom layer of carbon arranged in a honey-comb lattice, has various promising optical and electrical properties because of its linear dispersion band structure and zero band gap features. In this review article, we discuss recent research develop- ments on mid-IR graphene photonics, in particular ultrafast lasers and photodetectors. Graphene-photonics-based biochemical applications, such as plasmonic sensing, photo- dynamic therapy, and florescence imaging are also reviewed.

Ultrafast Stretched-Pulse Fiber Laser Mode-Locked by Carbon Nanotubes

Ultrafast fiber sources having short pulses, broad bandwidth, high energy, and low amplitude fluctuations have widespread applications. Stretched-pulse fiber lasers, incorporating segments of normal and anomalous dispersion fibers, are a preferred means to generate such pulses. We realize a stretched-pulse fiber laser based on a nanotube saturable absorber, with 113 fs pulses, 33.5 nm spectral width and ~0.07% amplitude fluctuation, outperforming current nanotube-based designs.

Modulation of photocarrier relaxation dynamics in two-dimensional semiconductors

Due to strong Coulomb interactions,two-dimensional(2D)semiconductors can support excitons with large binding energies and complex many-particle states.Their strong light-matter coupling and emerging excitonic phenomena make them potential candidates for next-generation optoelectronic and valleytronic devices.The relaxation dynamics of optically excited states are a key ingredient of excitonic physics and directly impact the quantum efficiency and operating bandwidth of most photonic devices.Here,we summarize recent efforts in probing and modulating the photocarrier relaxation dynamics in 2D semiconductors.We classify these results according to the relaxation pathways or mechanisms they are associated with.The approaches discussed include both tailoring sample properties,such as the defect distribution and band structure,and applying external stimuli such as electric fields and mechanical strain.Particular emphasis is placed on discussing how the unique features of 2D semiconductors,including enhanced Coulomb interactions,sensitivity to the surrounding environment,flexible van der Waals(vdW)heterostructure construction,and non-degenerate valley/spin index of 2D transition metal dichalcogenides(TMDs),manifest themselves during photocarrier relaxation and how they can be manipulated.The extensive physical mechanisms that can be used to modulate photocarrier relaxation dynamics are instrumental for understanding and utilizing excitonic states in 2D semiconductors.