Polymer waveguides are successfully fabricated by a simple method, which is incorporated with a lithography-galvanic (LIGA)-like and micromolding process. The refractive index of the UV polymer used in these experiments is changed by an extremely low electric field. The measured propagation loss is 0.32 dB/cm for 1.3 µm and 0.30 dB/cm for 1.55 µm. This process is easy, simple, and suitable for mass production.
This paper describes a simple and inexpensive technique to design and fabricate polygon microlens array using thermal pressing technique. Polygon microlens array molds were fabricated by using lithography and electroforming process. Microlens pattern was designed on a photomask and transferred to a substrate through photoresist patterning. The electroforming technology was used to convert the photoresist microlens patterns into metallic molds. A hot pressing machine was used to replicate microlens array in PC substrate. The compression pressure, temperature, and pressing time were key parameters to design and manufacture microlens array. The optical properties of these microlenses have been characterized by measuring their focal lengths. The average cylindrical microlenses radii of curvature were 315μm~420μm and the average sag heights were 2.98μm~4.03μm.
In this talk, we propose a novel tunable optical add/drop multiplexer (OADM), based on Asymmetric Bragg Coupler (ABC) and the liquid crystal as the active layer material. The asymmetric Bragg coupler is made of OG series polymer ridged waveguide. The liquid crystal is filled to cover the waveguide structure, which sandwiches between upper and bottom electrodes. When the external voltage applied, the index of liquid crystal changes to adjust effective index of coupler and inherently tunes the transmission spectrum of the device precisely. The transmission bandwidth is about 32.5GHz, and the tunable range is about 250GHz centered at 1.55nm.
This article describes a mass fabrication method for integrated microlens arrays mold by using UV lithography, thermal reflow, and electroforming process. The designed microlens array can be used for back light modules to enhance panel illumination. Refractive microlens with diameter 30 and 70 ?m in array are designed in certain layout. Lithographic fabrication of photoresist cylinder is applied by using the designed microlens array patterns. Thermal reflow resulted in photoresist melting and diameter shrinkage. Due to surface tension the shape of the photoresist cylinders changes to spherical shape. The sags of microlens with diameter 30 and 70 ?m are 7.5 and 25 ?m, respectively. The cross-section profile of microlens is measured by the Taylor Hobson’s profiler. It proved that thermal reflow can produce microlens array in photoresist materials. Replication process is applied by using electroforming process. Ni-Co composite electroforming can make metallic mold with hardness Hv 500 which is close to ordinary mold materials. Sputtering silver as a seed layer is applied onto microlens array in photoresist. Electroforming can start a “build-up” process to make required microlens array mold or mold insert. Refractive microlens arrays with high dense 700 lenses per mm2 were fabricated. The surface roughness of microlens arrays is less than Ra 0.02 ?m that adapt to the conventional lens surface roughness. Since the higher accuracy and lower cost of microlens fabrication methods are needed to meet the rapid growth of micro-optical devices, the contributed fabrication techniques are essential for the industry.
This paper presents a micromachining technique to solve the precision machining difficult for multi-fiber ferrule production. The LIGA technology is applied to make 1.2 mm thick V-groove mold inserts with dimensional tolerance 1 micrometers . It stars with x-ray mask fabrication, x-ray exposure, Ni-Co electroforming, and planarization to complete the metallic ferrule mold inserts. X-ray mask is developed here in low cost and accessible in Taiwan. The absorber thickness can be achieved to 30 micrometers in straightness. The single x- ray exposure can generate 1.2 mm thick PMMA after development process. This development proves the feasibility of many applications in x-ray micromachining. In the optical fiber passive components, connectors play a joint role int he whole system. Ferrule i the key part of a fiber connector. Since the development of the LIGA technology, high precision micro-components such the ferrule is considered to be applied. All multi-fiber ferrules require the same accuracy of pitch distance between two channels. The mold insert for ferrule fabrication becomes the most important part. Conventional precision machining has certain limitations on machining micro-components due to machining tool size and material wears. The LIGA technique can overcome these problems. It utilizes x-ray to penetrate polymer material and create molds, then applies electroforming to make metallic molds. These molds can be applied for molding process in mass production.
Micro-electro-mechanical system technology offers a wide number of applications for the military, industrial, and consumer markets. The miniaturization of components is a common objective for all studies. Refractive microlens array with density 400 lenses per cm2 are fabricated in three minutes by using hot embossing. The higher accuracy and lower cost of microlens fabrication methods are needed to meet the rapid growth of commercial devices. Higher density of microlens is achievable by a higher density mesh mold. Microlens diameters of 250-380 micrometers are shaped with various molds. Focal lengths of 185-225 micrometers are obtained by changing compression pressure and working temperature which are discovered in this experiment. Molding temperature effects on the surface tension in lens material as explored is essential. From accuracy of microlens arrays are less than Rt 0.1 micrometers that adapt to the form accuracy of the lenses. This article describes a mass fabricating method for microlens array by using hot embossing and the experimental results show its feasibility for practice.