On-chip Deep-spatial-frequency-shift Suner-resolution Microscopy Compatible With Labeled And Label-free Imaging

Photonic integrated chip(PIC)technology has developed rapidly in recent years,and it has excellent development prospects in applications such as integrated microwave photonics,optical quantum computing,and photonic integrated super-resolution(SR)microscopy.Photonic integrated SR microscopy is a technology that integrates the function of SR imaging into a small PIC.Compared with traditional SR imaging,it has the advantages of being integrated,reduced costs,and improved optical path stability.Spatial frequency shift(SFS)imaging based on evanescent wave illumination is compatible with photon integration technology to obtain a large field-of-view(FOV),fast,and integrated SR imaging.However,when the SFS magnitude exceeds the detection aperture twice or more,it will cause the spatial frequency missing so that the resolution of traditional linear SFS microscopy can only be increased to three times the Abbe diffraction limit.This thesis introduces Gallium Phosphide(GaP)semiconductor material with almost the highest refractive index in the visible light band to the study of deep-SFS SR microchips.A wide range of SFS magnitude control is realized by introducing high-refractive-index wafer and period-variable micro-nano grating fabrication;a tunable-SFS SR imaging compatible with label-free and labeled samples is realized through chip design and semiconductor chip fabrication.Further introduction of multi-physics control components can integrate labeled/label-free compatible optical SR imaging,microfluidics,electrical stimulation,pharmacological analysis,and other functions on a chip,providing a multi-functional and comprehensive research platform for the investigation of modern biological problems.The micromodule,installed on an ordinary microscope,realizes fast,large FOV and deep sub-wavelength resolution SR imaging capability.This research is of great significance to advance the practical application of deep-subwavelength SR imaging in biomedicine,life science,and material science.The innovations achieved are as follows:1.The mechanism of tunable deep-SFS is proposed,which breaks through the resolution limitation of 3 times the Abbe diffraction limit in linear SFS imaging and can promote the development of optical microscopy imaging technology.For a given optical system,how to break through the limitation of the diffraction limit on the space-bandwidth product is the key to obtaining SR detailed information.Traditional SR imaging methods,such as Stimulated emission depletion microscopy(STED)and Single-molecule localization microscopy(SMLM),compress the point spread function in the spatial domain to improve the resolution.However,their dependence on special fluorescent labels makes them unable to achieve label-free sample imaging.Exploring and developing a universal,labeled,and label-free compatible wide-field far-field SR microscopy method is currently a hot and challenging spot in the field.This thesis proposes a new mechanism from a spatial frequency domain engineering perspective to improve the imaging system's resolution,limited by the numerical aperture.SFS imaging can be achieved by adjusting the high spatial-frequency surface-wave illumination with the micro-nano structure design.The high-frequency components of the sample that the microscope cannot obtain are transferred from multiple directions to the system passband,and then the original spectrum and image are restored using a spectrum reconstruction algorithm.In theory,this method can make the low numerical aperture optical imaging system have infinite spatial-frequency far-field imaging capability.2.We develop the mechanism of three-dimensional tunable deep-SFS and propose a new method of three-dimensional multi-level precise control of the magnitude and direction of the evanescent field illumination wave vector,which effectively solves the problem of spatial frequency missing in deep-SFS SR imaging.In the linear SFS SR imaging,when the magnitude of SFS exceeds twice the detection aperture,there will be a missing of the spectrum.For this reason,a tunable deep-SFS imaging method based on an integrated optical waveguide chip has been developed to realize the precise multi-level control of the magnitude and direction of the illumination evanescent field's wavevector.In the horizontal direction,by controlling the lateral propagation direction of the two evanescent waves,the spatial frequency of the illumination pattern formed after their interference is adjusted to realize the detection of the object's spectrum domain in an extensive range without missing frequency.The tomographic saturation effect is adopted in the vertical direction to adjust the spatial frequency of illumination to achieve longitudinal SR microscopic imaging.These methods make the upper-resolution limit no longer limited by the detection aperture of the optical system but by the maximum evanescent field transverse wave vector that the illumination chip can provide.By using a dielectric waveguide material with an effective refractive index of 3.5,the lateral resolution and the longitudinal resolution of ?/9 and??/200(detection aperture is 0.9)can be achieved,respectively.Besides,compared to structured illumination microscopy(SIM)and other non-tunable frequency shift microscopy,the above method has better anti-noise ability.3.We design and fabricate a universally tunable deep-SFS SR microscopy imaging chip suitable for label-free and labeled samples.The chip is based on a GaP wafer,using the wafer's high refractive index and variable-period micro-grating design to achieve a wide range of illumination wavevector tunability and achieve tunable deep-SFS SR microscopic imaging compatible with label-free and labeled samples.Corresponding light-blocking structures are evaporated on both sides of the wafer through a double-sided photolithography process,which cleverly realizes high signal-to-noise ratio deep SFS SR microscopy imaging.The fabrication process is compatible with the complementary metal-oxide-semiconductor(CMOS)semiconductor process,which is suitable for large-area wafer-scale fabrication and is beneficial to reduce the cost of SR microscopy.4.We continue to increase the frequency shift depth and increase the chip's effective refractive index to a height(greater than 15)that is difficult for natural materials to achieve through the design of multi-layer metamaterials and realize the excitation and transmission of ultra-high spatial frequency shift,with which a resolution of sub-20 nanometers can be achieved in theory.