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排序方式: 共有160条查询结果,搜索用时 15 毫秒
1.
S. Schrader A. Penzkofer W. Holzer R. Velagapudi B. Grimm 《Journal of luminescence》2004,110(4):303-308
Optical, structural and morphological properties of thin films of polyparaphenylenevinylene (PPV) formed by an alkyl sulfinyl precursor route have been studied. Thin films were fabricated on an optical glass and on quartz glass either by spin-coating of the precursor solution or by layer-by-layer deposition using Langmuir–Blodgett technique. PPV precursor films were also spin-coated on gold-coated glass in order to study thin-film optical parameters by surface plasmon spectroscopy. We have been successful in forming about 40 precursor mono layers on quartz glass by Langmuir–Blodgett technique using optimized surface pressure and dipping conditions. After thermal conversion of the precursor layers good quality fluorescent PPV films of yellow colour have been obtained. Optical characterization of the films was carried out by linear absorption and emission spectroscopy, ellipsometry, and surface plasmon spectroscopy. Structural and morphological studies on the thin films were carried out by using X-ray scattering and atomic force microscopy. Wave-guided travelling-wave laser action has been achieved in a PPV film on quartz glass. The sample was transversally pumped with picosecond laser pulses (wavelength 347.15 nm, duration 35 ps). Laser emission occurred at 550 nm for pump pulse energy densities above . 相似文献
2.
Three-dimensional (3-D) ZnO random-wall nanostructures and one-dimensional (1-D) ZnO nanorods were prepared on silicon substrates by a simple solid-vapour phase thermal sublimation technique. Optical pumped random lasing has been observed in the ZnO random-wall arrays with a threshold intensity of 0.38 MW/cm2 in the emission wavelength from 380 to 395 nm. The optical gain was attributed to the closed-loop scattering and light amplification of the ZnO random-wall. The experimental result suggests that the morphology of nanostructure is the key factor to effect random lasing. 相似文献
3.
U. Narang R. Gvishi F. V. Bright P. N. Prasad 《Journal of Sol-Gel Science and Technology》1996,6(1):113-119
We report for the first time on the preparation of organically-doped room temperature processed sol-gel-derived micron scale optical fibers as platforms for chemical- and bio-sensors. Micron scale optical fibers are drawn from fluorescent dye-doped tetraethoxysilane (TEOS)-derived sol-gel solution processed under ambient conditions. Such a simple methodology to entrap organic and even bioactive species within the optical fiber offers many advantages over more conventional ways of immobilizing organic probes for the development of optical sensors. Specifically, we report on the photophysical properties of fluorescein (a pH sensitive fluorescent dye) and rhodamine 6G (R6G; laser dye) entrapped within sol-gel-derived optical fibers. We present the preliminary results on the viability of such doped optical fibers for chemical sensing. Our results demonstrate that a fluorescein-doped sol-gel-derived optical fiber responds to ammonia and acid vapors with a response time of 1–2 seconds. 相似文献
4.
Michael Höfner Björn Kobin Prof. Dr. Stefan Hecht Prof. Dr. Fritz Henneberger 《Chemphyschem》2014,15(17):3805-3808
We investigate the coupling of ladder‐type quarterphenyl to the photon modes of a dielectric ZrOx/SiOx microcavity at ultraviolet wavelengths. For a relatively long cavity (≈10 μm) with high‐reflectivity mirrors (0.998), optically pumped laser action is demonstrated in the weak‐coupling regime. We observe single‐mode operation with a threshold of 0.4 mJ cm?2. Strong coupling is achieved by using a short λ/2 cavity. We find pronounced anti‐crossing features of the molecular (0,0) and (0,1) vibronic transitions and the cavity mode in angle‐dependent reflectivity measurements providing Rabi splittings of (90±10) meV. All these features occur spectrally resonant to the exciton transition of ZnO demonstrating the potential of ladder‐type oligo(p‐phenylene)s for the construction of inorganic/organic hybrid microcavities. 相似文献
5.
Jianyang Hu Dongying Fu Chunli Xia Chi Zhang Lishuang Yao Chunlian Lu 《Liquid crystals》2020,47(4):508-515
ABSTRACTThis letter reports the optical pumped lasing behaviours of a three-layer Bragg resonance cavity consisting of dye-doped cholesteric liquid crystal (DDCLC) microdroplet, polyglycerol-2 and hollow glass microsphere. The function of PG2 is to control the parallel anchoring of the liquid crystal (LC) molecules on the surface of the LC microdroplet. The whispering-gallery mode (WGM), radial Bragg (photonic bandgap, PBG) mode and Bragg WGM (BWGM) are observed in DDCLC microspheres with different helical pitches and LC refractive indices. The formation mechanisms of six types of lasing emission conditions are analysed in detail. The study results present the prospect of controlling the output mode of the laser. Furthermore, such solid shell-based DDCLC microspheres have outstanding potential applications in miniaturised 3D Bragg lasers, sensors, and integrated and tunable optical devices. 相似文献
6.
ABSTRACTWe demonstrate a spatially and electrically tunable random lasing based on polymer-stabilized blue phase liquid crystal (PS-BPLC)-wedged cell. The spatially tunable random lasers can be obtained from the laser dye-doped PS-BPLC-wedged cell through changing the pump positions, where the emission wavelength of the random laser can be tuned due to the thickness gradient of the wedged cell, which affects the scattering mean free path. Additionally, applying different electric fields can also tune the laser emission wavelength. The changing of refractive index due to the Kerr effect leads to a change in the scattering mean free path, resulting in shift of lasing wavelength. This PS-BPLC-wedged cell device has a great potential in applications of speckle-free imaging, document coding, biomedicine and other photonic devices. 相似文献
7.
V. I. Borisov A. M. Krol V. P. Minkovich N. P. Minkovich 《Journal of Applied Spectroscopy》2000,67(2):360-363
We investigated the influence exerted by the radius of the bend of fiber light guides with light-transmitting cores of different
diameters on the transformation of the spectrum of longitudinal modes of the semiconductor laser radiation introduced into
them. It is shown that the bended segment of the light guide acts as a spectrum selector, and the spectral composition of
the radiation at the output of a light guide is different in different spots of the speckle structure.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 260–263, March–April, 2000. 相似文献
8.
We have described here the physical basis for lasing without population inversion (LWOPI). This type of amplification is obtained
basically by two mechanisms: (i) one is based on atomic interference and (ii) the other is based on Fano-type interference.
We have shown here, in H2 molecules, amplification without population inversion is feasible by considering both the mechanisms. 相似文献
9.
10.
Stimulated infrared (IR) emission from a condensed dielectric medium under exposure to a giant pulse of a ruby laser is reported.
This effect was predicted in the theoretical paper [1]. Experimental studies were carried out for a number of molecular liquids
in two experimental geometries. In the first case (“in transmission” geometry) the propagation direction of the detected IR
radiation coincided with that of the exciting radiation. In the second case IR radiation generated was detected in the opposite
direction. The angle of divergence of IR radiation was found to be of 10−2 rad, while the conversion efficiency with respect to the pumping intensity depended on the type of molecular liquid and varied
in the range of 0.05–0.6%. Possible microscopic mechanisms of generation of IR radiation under pumping of the dielectric medium
with visible or ultraviolet (UV) radiation are analyzed. 相似文献