Miniaturization Of Plasmonic Random Lasers

Random laser,one of the microcavity lasers,exhibts lots of advantages,such as without resonance cavity,simple structure and low cost,showing great potential applications in new flat panel displaying,ultraviolet laser,biological detection and optical communication.Light is multi scattered in disorder medium and forms feedback loops,and random laser emits after the spatial coherence.The investigation of random laser has been a focus in research work for the physical effects.In recent years,the plasmonic enhancement of metal nanoparticles and the strong optical gain characteristics of organic semiconductor have attracted the attention of researchers.In this thesis,the characteristics of metal nanoparticles and organic semiconductors are employed,and the investigation of micro random lasers is carried out.The main contents of the thesis are as follows: 1.The investigation of bimetallic nanoparticles fabricated by the laser-inducedtransfer technology.An ultraviolet laser is employed to induce metallic films on glass substrates.The metal nanoparticles are simultaneously fabricated on glass substrates(Donor)and PDMS substrates(Reciever).The morphology and extinction of metal nanoparticles are measured.The simulated interaction between nanoparticles of two kinds shows strong,conciding with measurement.2.The investigation of plasmonic random laser on the fiber facet.The plasmonic random laser,as a hemisphere coating,is fabricated on the fiber facet with a diameter of 400 ?m.The R6G-doped PDMS film is the active waveguide layer,and The Ag NWs are distributed in the active layer of PDMS,providing a three-dimensional plasmonic feedback.The photoluminescence spectrum of R6 G is enhanced by plasmonic feedback of Ag NWs,leading to a low threshold random lasing.The plasmonic random laser on the fiber facet is a hemisphere,working as a lens and concentrating the most emitted intensity in a small angel range along the axis of the optical fiber.This work not only demonstrates a simple and straightforward method for fabricating a plasmonic random laser on fiber facet but also proposes an efficient way to control the directional output from such random lasers.3.Investigation of plasmonic random laser of polymer.(1)Inverstigation of plasmonic random lasing in polymer microrod.The plasmonic random lasing in polymer microrod is fabricated by siphoning the polymer solution doped with silver nanoparticles into a 300-?m capillary tube and then evaporating the solvent.The Ag NPs provides a three-dimensional plasmonic feedback inside the polymer microrod due to the localized surface plasmonic resonance,enhancing the photoluminescence of polymer molecules significantly.The F8 BT microrod doped with Ag NWs has a stronger absorpbance of pump beam,but a lower absorpbance of the random lasing.Thus,the emission propagates in the polymer microrod,but the pump beam cannot propagates long in the polymer microrod due to the high absorption.The polymer microrod works as waveguide of emission,producing a directional random lasing.These results provide a utilized way for application of plasmonic random microrod lasers.(2)Investigation of RGB plasmonic random lasing from cascaded polymer slices.A red-green-blue random laser of cascaded polymer slices with Ag nanoparticles doping is achieved by a siphoning method.The important process is that a water column is siphoned between the two adjacent ink columns,and the immiscibility of water and polymer solution guarantees the formation of the polymers slices.The Ag nanoparticles show a broad plasmonic resonance spectrum.The radiations of the RGB random laser are enhanced and strong red-green-blue amplification simultaneously emits from the micro device.The red-,green-and blue-lines denote output emissions centering at 638 nm,569 nm and 469 nm,for R-,G-and B-components,respectively.The CIE chromaticity diagram is provided according to he intensities of emission at angles.This simple and straightforward approach has the potential for the application for compact integrated random laser source.4.Invesitgation of tunable random laser of thin film.Investigation of A dual-wavelength polymer random laser with step-type cavity?A dual-wavelength polymer random laser with step-type cavity is fabricated by a spincoating method.The phase separation results in the random microstructure,providing a multiscattering mechanism for random lasing.The output emissions center on 450 nm and 467 nm,when the pump spot totally irradiates on Cavity A and Cavity B,respectively.The peaks of 450 nm and 467 nm simultaneously emerge when the pump spot locates on the border of step cavities.Thus,the wavelengths and intensities from Cavity A and Cavity B can be adjusted by the illuminated area ratio.This work provides a simple approach of dual-wavelength emission,showing potentials for the compact devices of random laser.