Echo Wall Mode Optical Microcavity Coupling Type Construction And Study Of Optical Properties

Microcavities are optical resonators which confine the light field in micron or sub-micron volume.The light oscillates in the medium with discontinuous dielectric constants by reflection, scattering or diffraction at the interface.With extending the photon lifetime and reducing the optical modes, the spontaneous emission of gain medium(dipoles) inside the cavity will be significantly modulated by the local vacuum field, and lasing emission of low threshold can occur as well. Microcavities have been widely applied in various fields such as advanced light sources, signal processing and sensing technology.The coupled microcavities consisting of multiple cavities in array can artificially modulate mode patterns in space and frequency to generate a series of new physics phenomena and applications, thus have attracted great attentions.This thesis mainly focuses on the research work in the subject of "Study on the fabrications and optical properties of coupled microcavities based on whispering gallery mode". Research works include:the design and fabrication of semiconductor microdisk laser, single mode UV microlaser and high-Q polymer microring resonator for optical biosensing application. This thesis focuses on the following aspect:First, we designed symmetric half-spiral microcavities (SHSMs) with high-Q unidirectional emission properties.Mode field patterns and light emissionsare investigatedby the two-dimensional (2-D) finite-difference time domain (FDTD) method. The calculation results show thatan SHSM can support high-quality (Q-104) distorted whispering-gallery modes with directional emissions.Moreover, artificial controls on the Q factor and emission directionality are realized in the coupled size-mismatchedSHSMs, and unidirectional emission from the coupled cavity structure with a divergence of19°is achieved.Second, single-frequency lasing from coupled asymmetric microcavitiesis achieved in polymer microring, optofludics and semiconductor systems. By coupling two size-mismatched circular microcavities, multi-whispering-gallery modes are successfully suppressed and free spectrum range increases. The single-frequency laser emission is robustly obtained at the common resonance of the two cavities with the lowest loss.These achievements provide a simple and effective way to avoid the challenging fabrication of DBR mirror of high reflectivity in the ultraviolet range and small cycle grating.Third, we fabricated vertically coupled photonic molecule microdisk laserswith exceptionalspontaneous emission coupling to the lasing whispering gallery modes. The multi-stacks drastically suppress the photonic density of states in thevertical F-P modes, and enhance the spontaneous emission coupling factor β of WGMs to decrease the lasing threshold. The experiment shows the β of the double coupled microdisk laser is0.5which is15times higher than that of single disk laser. When three microdisks are vertically coupled, P can be up to0.72. At the same time, we observe the mode splitting induced by strong coupling between the microdisks and the coupling strength is0.4THz, which is at least one order higher than that between the quantum dots and cavity modes.Fourth, we fabricated SU-8polymer microring resonator and applied it to the the biosensing work. The device is systematically characterized and the intrinsic Q factor is8×105, which is the highest value so far. Taking advantage of this high performance, a surface mass density of12.7pg/mm2of BSA is detected due to the physical adsorption. The NEDL is approximately55.9fg/mm2in an intensity variation scheme. These results represent the best sensing performance which is achieved with the on-chip polymer ring resonator system.