The Studies On Random Laser Of Fiber And Thin Film

The pumping source of laser energy,the gain medium and the optical resonant cavity are three important components of the traditional laser.Random lasers also own them.However,the optical resonant cavity of random lasers is not comprised of total reflection lens,instead,it is made up of a closed loop of the photon in the disordered gain medium.The function of the closed loop is similar to the optical resonator.Random lasers possess many advantages,such as simple process,good stability,good directivity,light weight,low cost,low coherence and so on.Due to these advantages of random laser,it has been widely used in many fields including medical detection,nanotechnology,laser display,active devices,full field imaging,storage and so on.In this paper,the following work has been done in the research of random lasers..1.A new fiber random laser has been fabricated by the mixture which is formed from the rhodamine 6G?R6G?and polymethylmethacrylate?PMMA?.In order to measure the output light from random laser under different pump energy density,we employ the Nd:YAG laser which outputs laser of 532 nm as the pumping source of laser energy.When we adjust the pump energy density of Nd:YAG laser,it will appear the effect that the center wavelength of output laser is 602 nm,Full width at half maximum?FWHM?is 4.5 nm.And the threshold of the sample is 350 mJ/cm².2.Time characteristic of this new fiber random laser also has been measured.When the output light maintain a fine stabilization,we collected the signal of output light by photomultiplier and digital oscilloscope.Then,the random laser sample is removed and the signal of pump light also is collected.By comparing two optical signals,it is known that the pulse width of the output laser is about 15 ns,and the pulse width of the pump light is about 30 ns.3.The output laser intensity of all directions also have been measured.When the output laser maintain a fine stabilization,we measured the intensity of output laser in each direction by adjusting the angle between the fiber probe and the fiber random laser sample.The conclusion shows that the maximum of the intensity will appear when the angle between the fiber probe and the random laser sample is 90 degrees.In addition,The intensity of forward scattered light is greater than that of backward scattered light.4.Another new fiber random laser has been fabricated by the mixture which has certain concentration,and the method of manufacturing mixture is that the large molecular polymer PMMA,dye R6G and SiO₂ particles dissolve in trichloromethane respectively according to determined manufacture.The new fiber random laser do not emerge radiation light under the action of pump light.When the concentration of SiO₂particles is adjusted,different output light can be observed,but there is no obvious phenomenon about random laser.5.Two kinds of thin film random lasers with PMMA and without PMMA were fabricated from F8BT polymer,and they were measured respectively.It is found that the sample of random laser containing PMMA can not generate random laser,while the sample without PMMA produces output laser.The center wavelength of output laser is 580 nm,in addition,full width at half maximum of the laser is about 1.5 nm and the laser threshold is 2.84 mJ/cm².