基于LED的色度学实验研究

作为环保、节能、可智能控制的新型光源,发光二极管（LED）广泛应用于人们的现代生活、生产中,更有望替代传统的照明光源。以三基色LED为光源,制作了三路独立可调恒流电源,通过调节三基色光的不同配比实现加法混色,研究设计了加法混色的色度学实验,既可以直接观察混色后的实验现象,又能通过测量光谱数据得到色度参数。LED光源环保...     

大学物理演示实验室开放教学初探

开放式演示实验可以改变传统教学模式的弊端,充分发挥学生在教学中的主体和自主地位.从深化教学改革角度来看,应针对不同类型的学生开放不同的实验内容,密切联系工程生产生活实际,充分利用多媒体教学,培养学生创新实践能力.从利用教学条件的角度来看,要建立多项制度,细化演示实验室开放,努力实现可持续发展.     

基于COMSOL软件下截锥体电阻的计算

本文应用Comsol软件讨论了截锥体内电势和电流的分布,并计算了截锥体的电阻.     

High-power 10-GHz self-mode-locked Nd:LuVO<Subscript>4</Subscript> laser

We report on a high-power diode-end-pumped self-mode-locked Nd:LuVO₄ laser with the pulse repetition rate up to 9.52 GHz for the first time. The large third-order nonlinearity of the Nd:LuVO₄ crystal is exploited to efficiently achieve a fairly stable self-mode-locked operation without any additional components. The detailed characteristics of the compact efficient self-mode-locked laser are experimentally investigated and theoretically analyzed. With the incident pump power of 2.6 W, the average output power up to 0.54 W is generated with the pulse width of 7.9 ps at the pulse repetition rate of 9.52 GHz.     

Efficient and compact intracavity-frequency-doubled Nd:LuVO<Subscript>4</Subscript>/LBO laser at 538 nm end-pumped by a fiber-coupled laser diode

We report a diode-pumped Nd:LuVO₄ laser emitting at 1076 nm, based on the ⁴ F _3/2−⁴ I _11/2 transition, generally used for a 1066 nm emission. A power of 689 mW at 1076 nm has been achieved in continuous-wave (CW) operation with a fiber-coupled laser diode emitting 17.8 W at 809 nm. Intracavity second-harmonic generation (SHG) in CW mode has also been demonstrated with a power of 105 mW at 538 nm by using a LiB₃O₅ (LBO) nonlinear crystal.     

Diode-pumped Pr<Superscript>3+</Superscript>:YAlO<Subscript>3</Subscript>/LBO violet laser at 374 nm

We report a diode-pumped Pr³⁺:YAlO₃ laser emitting at 747 nm. A power of 232 mW at 747 nm has been achieved in continuous-wave operation with a diode emitting 2 W at 448 nm. Furthermore, intracavity second-harmonic generation in continuous-wave mode has also been demonstrated with a power of 52 mW at 374 nm by using a LBO nonlinear crystal. The fluctuation of the violet output power was better than 2.3%. The beam quality M ² value is 2.2.     

Flat supercontinuum generation covering C-band to U-band in two-stage Er/Yb co-doped double-clad fiber amplifier

Supercontinuum generation in the gain fiber in two-stage nanosecond pulse Er/Yb co-doped double-clad fiber amplifier had been demonstrated for the first time to our knowledge instead of the conventional method in which nonlinear fiber was pumped by lasers. The Er/Yb co-doped double-clad fiber acts as the gain media and nonlinear media. This route reduces the splice between fiber laser and nonlinear fiber. The supercontinuum was achieved with spectrum range from 1530 nm to beyond 1700 nm at 6 W output power covering the total C-band to U-band. From the analyzing of the spectra at different stages in the amplifiers, it can be found that it is the modulation instability in the anomalous dispersion regime that initiates the supercontinuum gereration.     

Solid-state dye lasers based on polymethyl methacrylate modified with methanol

Solid-state dye samples based on modified polymethyl methacrylate with methanol (MPMMA) doped with pyrromethene 567 (PM567) were first prepared. The effects of volume percentage of methanol on the laser performances of the samples, including spectra properties, slope efficiency and photostability were studied. The highest slope efficiency 66.39% was obtained in the sample (MMA:methanol = 16:4). Pumping the samples at a repetition rate of 5 Hz with a pulse energy as high as 100 mJ (the fluence was 0.26 J/cm²), the output energy dropped to half of its initial value after approximate 156720 shots and the corresponding normalized photostability reached 101.86 GJ/mol in the sample (MMA:methanol = 17:3). Our results indicate that it can obtain a high slope efficiency and good photostability for a solid-state dye laser using MPMMA as solid hosts.     

Fractional scanned carbon dioxide laser induces collagen remodelling in murine dermis

Resurfacing using a fractional CO₂ laser shows an important promise in the therapy on photoaged skin. The present study investigated that fractional CO₂ laser with a special sequential scanned manner induced the collagen remodelling in murine dermis. The results showed that laser resulted in the improvement of elasticity and histology in the murine dermis, meaning laser efficacy depends on both of the collagen formation and organization. We further investigated the relations between skin elasticity and type I, and type III collagen. These data demonstrated that laser could significantly lead to the collagen remodelling in murine dermis and induce neocollagenisis as a mode of resurfacing.     

Microjoule level femtosecond optical pulses with double-cladding fiber-based nonlinear chirped-pulse amplification

An all-fiber high-energy nonlinear chirped-pulse amplification system with two-stage double-cladding fiber amplifiers is presented in this paper. It generates pulses with the energy up to 10 μJ at 20 kHz repetition rate and total accumulated nonlinear phase shift as large as 12.8π. The pulses can be compressed to 137 fs with the compensation of mismatched third-order dispersion by self-phase modulation in the fiber amplifiers.