Hongchen Guo

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The ultrafast saturable absorption in graphene is experimentally and theoretically investigated in the femtosecond (fs) time regime. This phenomenon is well-modeled with valence band depletion, conduction band filling and ultrafast intraband carrier thermalization. The latter is dominated by intraband carrier-carrier scattering with a scattering time of 8 ((More)
Throughout history earth-abundant copper has been incorporated into textiles and it still caters to various needs in modern society. In this paper, we present a two-step copper metallization strategy to realize sequentially nondiffusive copper(II) patterning and rapid copper deposition on various textile materials, including cotton, polyester, nylon, and(More)
In conventional frequency conversion based on chi(2)-induced nonlinear optical effects, a number of phase-matching techniques have been deployed to resolve the phase mismatch between the interacting waves. In this work, we report that in the quasi-phase-matching scheme, the accumulation of the phase mismatch can induce a quasi-phase-mismatch effect. And on(More)
The ultrafast saturable absorption in graphene is experimentally and theoretically investigated in the femtosecond (fs) time regime. This phenomenon is well-modeled with valence band depletion, conduction band filling and ultrafast intraband carrier thermalization. The latter is dominated by intraband carrier-carrier scattering with a scattering time of 8 ((More)
Photocatalytic microreactors have been utilized as rapid, versatile platforms for the characterization of photocatalysts. In this work, a photocatalytic microreactor integrated with absorption spectroscopy was proposed for the real-time monitoring of photocatalytic activity using different catalysts. The validity of this method was investigated by the rapid(More)
Saturable absorption of graphene was experimentally and theoretically investigated in femtosecond time regime with the z-scan technique. The initial ultrafast carrier relaxation time was determined to be ∼8(±3) fs. Such ultrafast dynamics is far beyond the time resolution of other ultrafast techniques with typical hundred fs laser pulses. Our(More)
We report a compact all-solid-state mid-infrared optical parametric oscillator with wide tenability using periodically poled 5 mol % MgO-doped LiNbO<inf>3</inf> with a multiple-channel structure design and pumped by a compact diode-pump solid-state laser operating at 1.064 &#x00B5;m. Wide tunability from 1.44 to 1.58 &#x00B5;m at the signal beam wavelength(More)
Morphological defects were generated in an undoped 3D graphene structure via the involvement of a ZnO and Mg(OH)2 intermediate nanostructure layer placed between two layers of vapor-deposited graphene. Once the intermediate layer was etched, the 3D graphene lost support and shrank; during this process many morphological defects were formed. The(More)
3D reconstruction from the microscopy images of serial sections plays an important role in analyzing structure of biological specimens, such as neuronal circuits in brain tissue. This paper is focusing on the 3D reconstruction of synapses which is a branch of micro reconstruction of brain. Having analysed the structure of synapses, we first detect and(More)
The interactions between electromagnetic wave and photonic quasicrystals are investigated. A terahertz (THz) source with multi-frequency modes in an optical LiTaO(3) superlattice produced by quasiperiodic (Fibonacci) domain-inverted ferroelectric material is demonstrated experimentally. Using the canonical pump-probe experimental technique, THz radiations(More)
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