Mode Mapping And Sensing In Integrated Optical Microcavity

The development in the miniaturization of optical devices not only reduces power consumption,but also improves the corresponding performance.With the maturity of micro-and nano-fabrication technology,integrated optical microcavity has become a research hotspot.Due to the high quality factor and small mode volume,it has shown great potential applications in the optical communication fields,such as microlasers,filters,and sensors.However,as for mode mapping on the field distribution in the microcavity,improvement of quality factor,realization of directional laser emission,and microstructure imaging,traditional research methods face severe challenges including high cost,low stability,and bad controllability.To address these issues,this thesis focuses on field distribution mapping and mode control in both theory and experiment.To map the field distribution in an optical microcavity,a non-radiative recombination induced thermal effect is proposed as imaging mechanism.When the microcavity surface is pumped by a nanosecond laser,the local refractive index will change due to the thermal effect.Consequently,the mode mapping could be realized via correlating the field intensity at the pump spot with the transmission at the fixed probe wavelength.The imaging scheme is experimentally verified by resolving the whispering gallery modes with different radial orders in circular microcavity.In addition,mode mapping on four sets of different field distributions as well as the observation of reversible quantum-assisted tunneling phenomenon is achieved in a deformed microcavity.In order to further improve the quality factor of microcavity,a scheme of mutual coupling of different modes in a deformed microcavity is proposed.In simulation,the eigenvalues of the Quadruple deformed microcavity are solved,and it is found that the diamond mode and the six-bounce mode interact at the frequency crossing,which makes the quality factor of the latter increase significantly.In experiment,based on the above mentioned mode mapping scheme,the two coupled modes could be confirmed and the improvement in the quality factor of six-bounce mode is observed in a silicon deformed microcavity.By measuring the far-field intensity distribution of the microcavity at the coupling point and other wavelengths,the reasons for the phenomenon are identified.In order to realize the directional emission from the integrated laser in the visible band,bus waveguide coupled circular cavity is fabricated on a single-crystalline perovskite microplate.Upon femtosecond laser pumping,laser emission based on whispering gallery mode couples out via the waveguide.Based on the inversely proportionally relation between the mode spacing of lasing peaks and the size of circular microcavity,the Fabry-Perot laser from the bus waveguide is excluded and the waveguide induced out coupling from the circular microcavity is confirmed.By introducing a deformed microcavity outside the circular cavity to control the clockwise and counterclockwise components inside the circular cavity,the unidirectional laser emission from the waveguide is realized.To realize the sensing of micro-and nanostructures,a super-resolution imaging scheme for active microcavities is proposed.Based on the single-crystalline perovskite microplate,the laser emission from perovskite could be scattered by micro-and nanostructure to the far field,and thereby the real-time and far-field imaging of the structures could be achieved via directly collecting the images.High signal-to-noise ratio up to 9 d B is achieved after removing the fluorescence signal in the background.Furthermore,a pair of polystyrene microspheres with a separating distance of 41 nm were distinguished effectively.The single perovskite microplate is transferred to the silicon-based metastructure to achieve super-resolution imaging of more than 100 silicon strips in a large field of view.The intensity distribution of the scattered laser is extracted,and the average period value of the array structure is calculated.Compared with the result based on scanning electron microscope,the imaging error is less than 5 nm.The effects of different areas,thicknesses and placement positions of the single microplate on the imaging results are discussed in detail,and the reliability of the active perovskite microcavity super-resolution imaging is verified.To conclude,this thesis not only provides novel techniques for the mode mapping in the microcavity,but also serves as important references in the potential applications of microcavities in the on-chip integrated systems.