Browsing by Author "Sun, Boshu"
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Item Laser direct writing metalens with phase change material and application(University of Delaware, 2021) Sun, BoshuWith the further study of phase change materials, more applications have been found to applied in many industries. The idea of photonic integrated circuit has come up as the mature electrical circuit is getting hard to meet demand of higher speed communication. Among various kinds of optical devices, phase change material (PCM) is ideal to be utilized to be tunable devices. The reversible change of phase states provides multiple possibilities for modifying optical signals. In term of imaging, the thickness and weight of conventional lens must be increased to meet the demands of numerical aperture and resolution, so the ideal of ‘flat’ diffraction lens came out. ☐ The light source of laser written diffraction lens is relative with the feature size of reaction between laser and PCM. To focus near-infrared light (wavelength ~= 1550 nm), the feature size of ablation must be limited. So, the dosage process of PCMs is included in this thesis. ☐ This thesis mainly illustrates the laser inscription applications on chalcogenide PCM. Diffraction lens are the dominant devices to be designed. The first two chapters are the background of diffraction lens fabrication designs, which is 1-D lens based on different PCM material. They include Ge2Sb2Te5 films, Al2Se3 and Tellurium flukes. The features of PCM and their reactions with laser will be illustrated in theses chapter. Before the fabrication of the lens, dosage and simulation will be clarified in chapter 3 and 4. In chapter 5, the experimental information of fabrication will be shown here like the setup and optical path of laser. After fabrication, the performance of the designed devices will be evaluated in chapter 6. The final chapter will conclude the devices and their future.Item Photocatalytic Oxidation in Few-Layer Tellurene for Loss-Invariant Integrated Photonic Resonance Trimming(Advanced Optical Materials, 2023-05-05) Mao, Dun; Wang, Yixiu; Lee, Hwaseob; Chang, Lorry; Wang, Feifan; Wu, Darren; Xiao, Yahui; Sun, Boshu; Ullah, Kaleem; Booksh, Karl; Wu, Wenzhuo; Gu, TingyiTwo-dimensional (2D) materials with unique physicochemical properties promote photocatalytic activities. As the 2D material composites research studies the statistical average of complex catalytic behaviors, an integrated photonic platform allows for clean and single flake level photo-catalytic investigations with precisely quantified photocatalytic activities. In this paper, fluence-dependent photo-oxidation in two-dimensional Tellurene (2D Te) is tracked by the evanescently coupled micro-resonator. Nearly 32% of oxidation is achieved in ≈10 nm 2D Te flake, compared to only 4.5% oxidation in a 30 nm sample, probed by the resonance shift in silicon micro-ring resonators substrate. The wider bandgap in the few layers of 2D Te allows faster charge transfer to adsorbed oxygen for a more efficient photocatalytic redox reaction. The photo-oxidation in hybrid 2D Te results in invariant lineshapes of optical transmission resonance for wavelength trimming (more than 3× resonance bandwidth). The low threshold power, near-infrared, and in-waveguide resonance trimming scheme is compatible with most integrated photonic setups for easy fixing of the nanofabrication-induced random resonance deviation for integrated photonic circuit applications in wavelength-division-multiplexing systems and spin qubits quantum computing.