The energy issue has been gaining a lot of attention in many countries in recent years. Among the kinds of energies, the solar energy is one of the most interesting topics of them. In addition to the fabrication process and raw material, another focal point aims at solar concentrator. This paper shows a new and easy way to increase the solar energy efficiency. We utilize the micro-optics principle to design and fabricate a microlens array of the solar concentrator. With this concentrator, it can enhance the optical absorption on the solar cell. The microlens array concentrator (MLA-concentrator) is different from the conventional concentrator. The MLA-concentrator does not need any electric equipment to follow the sunlight, and it is easy to manufacture. The size is smaller than conventional concentrator, especially. The MLA-concentrator can decrease the reflection of light at oblique angles and increases the second reflection at the interface between concentrator and solar cell, which makes the sunlight uniform. It also has an interesting characteristic which is the pantoscopic incidence. This new-type MLA-concentrator is fabricated by using LIGA-like process, and then it is integrated to the solar cell for electricity generation. Most important, this kind of structure can be combined with all kinds of solar cell. The solar cell with the MLA- concentrator adds the total watt 3.96% in all angle.

In recent years, microlenses (ML), which are micro-scale spheres, have been used to overcome physical diffraction limit of optical microscopy (~200 nm). Although the use of such ML has provided highly resolved images of objects beyond the Abbe optical diffraction limit, the process needs to be refined before it can be applied widespread in materials, biological and clinical research. In this research work, we have implemented experiments on super-resolution imaging utilizing MLs of different refractive indices (n) and diameters to provide the scientific and engineering communities with practical guidelines for obtaining high resolution images with ease. With the support from experimental imaging data as well as FDTD simulations, we have shown that optimal super-resolution imaging with microspheres was accomplished under specific parameter range. We have identified ML with n=1.51 as a preferable choice over those MLs with n=1.4, 1.93, and 2.2, because of high reliability and high magnification for ML with n=1.51. With n=1.51 in mind, we have identified a diameter range from 15 μm to 50 μm provides high resolution and magnification for practical purposes. We show that other ML diameters provided high resolution as well; we believe that ML diameters between 15 μm and 50 μm are practically preferred. We were able to achieve <150 nm resolution and further refinement of this tool can potentially yield higher quality imaging results. Ideally, MLs will eventually be directly incorporated as a modular device in an optical microscope providing the researchers an effective, noninvasive, and economical alternative to complex super resolution microscopy techniques. To improve scanning efficiency, we also proposed microtubule (MT) based imaging. With the demonstration of theoretical optics, we conclude, at present time, that there are some practical concerns for MT-based imaging technique that may limit its application as super-resolution imaging technique. For example, MT-based imaging appears to possess a lower contrast than ML-based technique. Thus, although the concept of MT-based imaging is theoretically possible, we think that more work is needed to utilization of this tool for practical applications.

This dissertation is aimed towards using stimuli-responsive pNIPAm-co-AAc microgels synthesized via free-radical precipitation polymerization to prepare stimuli-responsive hydrogel microlenses. Chapter 1 gives a detailed background of hydrogels, and their applications using responsive hydrogels. Chapter 2 describes the use of colloidal hydrogel microparticles as microlens elements and the fabrication method to form the hydrogel microlens arrays via Coulombic interactions. Chapter 3 shows the demonstration of tunable microlenses prepared by the method used in Chapter 2. In this chapter the microlenses are subjected to various pH and temperature in aqueous solutions. Chapter 4 describes that the microlens arrays constructed on Au nanoparticle-functionalized glass substrates by self-assembly display dramatic changes in lensing power in response to an impingent frequency-doubled Nd:YAG laser. The microlens photoswitching is highly reversible, with sub-millisecond lens switching times. Chapter 5 describes the development of bioresponsive hydrogel microlenses as a new protein detection technology. The microlens method is shown to be very specific for the target protein, with no detectable interference from nonspecific protein binding. Chapter 6 describes the use of bioresponsive hydrogel microlenses as a label-free biosensing scaffolding. These microstructures simultaneously act as the biosensors scaffolding/immobilization architecture, transducer, amplifier, and also allow for broad tunability of the analyte concentration to which the microlens is sensitive.

For the shortage of energy and the environmental issues, the development of solar cells has become an important technology. However, solar cells have low efficiency of energy conversion due to their high surface reflection on a flat Si substrate which is 38 %. To decrease the surface reflectance of the silicon solar cells, anti-reflection coatings (ARCs) are proposed on the solar cells. We use Lighttools software to investigate several kinds of ARCs to decrease the surface reflectance. We first consider the reflectance of the single-layer ARC with quarter wavelength. It can effectively decrease about 30 % surface reflection as compared with a flat Si substrate. The half-cylinder texture and the wave texture are designed on a PMMA single-layer coating. It is found that the half-cylinder ARC and the wave ARC can usefully diminish the surface reflectance for perpendicular light. Low reflectance can be achieved in the hemispherical microlens ARCs over an extended spectral region for omnidirectional incident light. The impact of the microlens sizes, periods, and arrangements are investigated. The lowest normal reflectance of the closely-packed triangular-lattice hemispherical microlens ARC is 4.8%. By adding smaller hemispherical microlenses, the surface reflectance of the hemispherical microlens ARC can be as low as 1.86 %. To obtain the lowest average surface reflectance, both-sided patterned surface texture ARCs are designed. Their lowest average surface reflectance is 2.24%. Finally, we simulate the reflectance of the nanowire ARCs. The influence of the wire length and the angle of inclination are discussed for high-efficiency and low-cost solar cells.

A study of double-variable-curvature microlenses (DVCM) for promoting coupling efficiency between the high-power 980-nm pumping laser diodes and the single-mode fibers has been proposed. In comparison with the previous works on asymmetric fiber microlenses fabricated by the multi-step processes with complicated fabrication, the advantages of the DVCM structure for achieving high coupling are a single-step fabrication, a reproducible process, and a high-yield output. In the fusing procedure, the slight arc fusion was mainly applied for fine polishing merely instead of reshaping for the reason that the fabricated double-variable-curvature fiber endface (DVCFE) was very close to the ideal shape. Hence, the fabrication time was reduced and the yield was promoted due to the withdrawn step of tip elimination. In this study, the geometric center of the fiber was defined through, the cladding diameter and the core diameter, for comparison to measure the offset. The offset measured by the core diameter was more accurate and coincidence with the coupling efficiency in the experiment. In the fabricated 45 DVCMs, to achieve the average coupling efficiencies higher than 84%, the offsets were ought to be controlled in merely less than 0.6£gm with the curvature radii in the minor axis ranged from 2.4 to 2.9£gm (with tolerance of 0.5£gm). Alternatively, the offsets were ought to be controlled in less than 0.3£gm though the curvature radii in the minor axis ranged from 2.4 to 3.7£gm (with larger tolerance of 1.3£gm). However, it was more difficult to control over the offsets than the curvature radii in the minor axis while fabricating the DVCMs. In conclusion, to achieve higher yield, it was relatively practical to control the offsets of fiber microlenses to be less than 0.6£gm with 2.4 to 2.9£gm curvature radius. As a result, the coupling efficiencies were all higher than 80%.

Computer-aided design and simulation software are used in this thesis. AutoCAD is used to create pattern and mask; Pro/E is applied to build 3D model. TracePro software is used to simulate the optical performance. We use software for simulation and analysis. The data from simulation and analysis will be helpful to increase the strike-rate in process. Photolithography process is applied in this thesis for gapless crack polygonal lens array fabrication. In this process, photo resistance, AZ-4620 is spun on the substrate, and expose it after mask alignment, followed by the developing process. The cylinder column with the same size in diameter is formed after this process. Next, apply heat to photo resist. The cylinder structure becomes semi-sphere due to surface tension effect. Then, sputter silver layer on the semi-sphere. The semi-sphere becomes metal mold after nickel electroforming. Nickel alloy core is formed after electroplaing. Then, apply UV cuve resin on the nickel alloy core, and spinning out the extra UV glue. Then, cure it with UV light. Gapless crack polygonal lens array is completed after this series process. The result shows that it can be applied on different optical devices.

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In this paper, we searched the parameter of BEF (Brightness enhancement film) using commercial FRED server for backlight module. The pattern analysis was carried out to understand its characteristic. The current structures used in LCD backlight are double-layer BEF. In addition, BEF of 3M takes the lion¡¦s share. But this may increase the thickness and cost of backlight module. In order to avoid those disadvantages, we tried to design single-layer BEF and characterize the effect through parameters study by using FRED software simulation. pyramid-shaped microlens array of BEF was constructed. Therefore, the effect of the variation of the structure parameters can be analyzed, such as prismatic degree (£c), prismatic structure on the brightness enhancement. It can be found from the result of simulation that the changes of the prismatic degree (£c) of 85 degree influence the brightness enhancement the most.

A study of double-variable-curvature microlenses (DVCM) for promoting coupling efficiency between the high-power 980-nm laser diodes and the single-mode fibers has been proposed. The purpose of the fiber microlens fabrication was to make the mode field match between the laser beam and the fiber as the beam propagating through the fiber microlens. To make the mode match, the shapes of the fiber microlens demanded nothing else but the offset and the curvature radii in minor and major axes. The double-variable-curvature fiber endface (DVCFE) was manufactured through a single-step fully automation grinding process and had less average offset of 0.3£gm, consequently. The radii of curvature in minor and major axis were controlled as an average of 1.2£gm and 33.6£gm, respectively. In the fusing procedure, the slight arc fusion was mainly applied for fine polishing merely instead of reshaping for the reason that the fabricated DVCFE was very close to the ideal shape. Hence, the fabrication time was reduced and the yield was promoted due to the withdrawn step of tip elimination. Furthermore, while the fusion parameters were set to be: fusing distance: 10£gm, arc intensity: 3bits, and fusing time: 200ms in the slight fusion process, the offset was reduced to 0.2£gm due to the shape constraint and surface tension of the DVCFE. And the radii of curvature increased 1.7£gm to 2.9£gm in the minor axis and increased 4.5£gm to 38.1£gm in the major axis, respectively. Owing to the controls of the fully automated grinding procedure and the omission of the tip elimination, the coupling efficiency and yield were improved. As a result, in the experiment, the average and maximum coupling efficiency of 83% and 88% were demonstrated, respectively. And the coupling efficiencies of the 20 samples were higher than 80%. In other words, the proposed DVCM structure of this study was a high coupling efficiency, a high yield output, and reproducible and fully automated single-step grinding process.

Two new schemes of fiber microlenses for coupling between the high-power 980nm laser diodes and single-mode fibers (SMFs) are proposed. The quadrangular-pyramid-shaped fiber microlens (QPSFM) is fabricated by grinding a quadrangular-pyramid-shaped endface and then through heating in a fusing splicer to form an elliptical microlens endface. In comparison to the traditional wedge-shaped fiber microlens, the QPSFM structure can control two axial curvatures to form an elliptical microlens endface, and then control the aspect ratio of fiber far-field pattern to match the elliptical mode fields of lasers. The coupling efficiency of 83% for the QPSFM has been demonstrated. Another scheme of fiber microlens is the conical-wedge-shaped fiber microlens (CWSFM). The CWSFM is fabricated by grinding a conical-shaped fiber endface, then grinding a pair of wedge planes on the conical-shaped fiber endface, and finally through heating in a fusing splicer to form a good elliptical microlens endface. The coupling efficiency of 84% for CWSFM has been demonstrated. The fabrication of QPSFM requires five-step grinding processes. The range of grinding offset is 0.5~3.0£gm, and the average of grinding offset is 1.5£gm. The fabrication yield of QPSFM is low due to the large grinding offset. The fabrication of CWSFM requires only three-step grinding processes. The range of grinding offset is 0.3~1.5£gm, the average of grinding offset is 0.8£gm. The fabrication yield of CWSFM is high due to the small grinding offset. The fabrication yield is about 60% for 70% coupling efficiency; whereas the fabrication yield becomes 96% for 60% coupling efficiency. The laser-to-SMFs coupling of the fiber microlens was modeled based on the diffraction theory. The coupling efficiency, the tolerance of alignment, and the tolerance of fiber microlens offset were calculated according to this model. There is a good agreement between the simulation and the experiment values. In this study, two new scheme of fiber microlenses of the QPSFM and CWSFM with high coupling efficiency have been demonstrated. The CWSFM structure has the benefits of simple process and high yield that is suitable for use in commercial high power laser module.