| Because of the total reflection when light propagates in the edge of a the rotational symmetry cavity, light is strongly limited in dielectric microcavity oscillation to produce discrete vibration modes, these modes usually are called whispering gallery modes(WGM), this cavity is called whispering gallery mode resonator. With small mode volume, high quality factor, low lasing threshold and easy to be integrated, WGM microcavity resonator is widely application in nonlinear optics, quantum dynamics, low threshold lasers etc. fields. However, due to the isotropic lasing and the multi-modes lasing, the application of WGM microcavity resonator is limited in a wide range of areas. In order to achieve directional lasing of the microcavity, researchers proposed asymmetric microdisk structure, such as the column shaped cavity, spiral cavity. In this paper, we main work is to prepare microdisk resonator with holes by femtosecond laser direct writing(Fs LDW) technique and study the lasing performance of the resonator.In recent years, because of its high precision, three-dimensional processing, controllable pattern, Fs LDW has gradually become the main technical means in the micro-nano machining field. Through a high numerical aperture oil immersion lens, femtosecond laser pulse is focused to photoresist material doped gain medium. The two-photon occurs near the focus of the laser pulse, which can lead to light induced polymerization effect of organic monomer. Through laser focus scanning point by point controlled by the program, the specific region of the material occurs photo polymerization according to the design pattern. Finally, the three-dimensional structure of the design can be obtained by removing the non-exposed area with the developer solution. In this paper, we use the FsLDW technique to induce the two-photon polymerization of photoresist materials, which can be used to prepare shape controllable arbitrary three-dimensional structure.In 2006, J. Wiersig proposed that a microdisk fixed the air holes could produce directional lasing with high Q mode. This paper verified that the disk with holes micro-resonator can produce directional lasing and single-mode lasing in the experiments. The microdisk diameter is 20 μm, the hole diameter is about 0.6 μm, the distance between the hole and the edge of the microdisk is 1μm. The materials for preparation of the microdisk is SU-8 photoresist doped with gain medium Rhodamine B, SU-8 has good optical properties and mechanical properties, and the light absorption is very low above 400 nm.Firstly, this paper introduces the current development situation and application of WGM micro-resonator, and then introduces the technology of Fs LDW. Then, we prepared microdisk resonator with holes using FsLDW system, and characterized the geometric morphology of the microdisk. The lasing performance of microdisk with holes was characterized through the picosecond laser pumped system. It is found that the threshold of the microcavity with holes laser is smaller compared with traditional microdisk lasers and there is a higher Q value, its Q value is more than 2600, and the line width of the lasing peaks is narrow, only 0.24 nm. Moreover, disk with holes microcavity lasers also realize the directional output of single mode lasing, and its far-field divergence angle is about 10°, and the result of experiment was analyzed by the Rsoft software. Due to low consumption and good chemical compatibility of the polymer, the advantages of the prepared disk with holes microcavity laser make it have a great application prospect in the integrated organic optoelectronic devices in this paper. |
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