In this paper, we developed a nonsilicon surface- micromachining technique that uses a thick photoresist film and a spattered copper layer as two sacrificial layers and uses the electroplated ferronickel (FeNi) as the structure material. The proposed nonsilicon micromachining process is simpler, with relatively low temperature, and more flexible for various materials. By using such technique, silica or glass can be used as an optical material. Several out-of- plane multilevel diffractive optical elements (DOE's) including gratings, phase Fresnel lenses and some other optical components supported by FeNi microstructures are successfully constructed on the silicon wafer. Those DOE's are fabricated by several steps both of photolithography and reactive ion etching on the spattered silica layer. This technology offers a new approach to fabricate high quality phase micro-optical elements for free-space integrated micro-optics and other applications.
In this paper, a novel optimization algorithm, termed genetic local search algorithm (GLSA), that combines a genetic algorithm (GA) with a local search technique is proposed to design DOE's. This hybrid algorithm performs an improved, more goal-oriented search compare to a purely GA. A 1:17 cross pattern fan out grating and a uniform focal plane intensity profile generator are designed to demonstrate the algorithm we proposed. Numerical results proved that the proposed algorithm are highly robust and efficient. High-quality DOE's are achieved by using the algorithms we proposed.
For many MEMS devices, silicon including polysilicon so far is the most idea materials, therefore the silicon micromachining technology has been well developed. However, for some MOEMS devices and systems, using other materials such as glasses, quartz, dielectric and ferroelectric crystals or ceramics, compound semiconductors, metals and alloys are also available or unique. As a result, it is necessary to develop the nonsilicon micromachining technology. In this paper, the nonsilicon micromachining process and some devices such as different kinds of micro- hinges will be reported.
The combination of micro-optics and integrated optics with microelectronics and micromechanics to create a broader class of micro-opto-electro-mechanical system (MOEMS), various thin films and related technologies such as the bulk and surface micromachining and LIG technology for the elementary structures and devices of MEOMS are discussed.
Based on the discussion of general principles and fundamental phenomena in nonlinear guided-wave optics, this article presents a review of second-order and third-order nonlinear optical waveguide devices including second harmonic generation, nonlinear directional coupler, nonlinear grating reflector, nonlinear M-Z interferomenter, etc.; the analysis and comparison of nonlinear waveguide materials and measurement techniques; and an review of the research fields and prospects of nonlinear integrated optics.
Resonance-enhanced anti-stokes of stimulated four photon mixing is demonstrated for the first time in an Er3+ doped silica fiber under the excitation of a 1064 nm laser. The enhancement of 977 nm anti-stokes of stimulated four-photon mixing by the excited state 4I11/2 of Er3+ has been observed. After the fiber being prepared for efficient SHG, the spectra of stokes and anti-stokes stimulated four-photon mixing were measured again and found to have shifted 2 nm, respectively. We attribute this phenomenon to photo induced refractive-index changes in the fiber: one is caused by the short wavelength light absorptions of GeO, and the other is by the change of intensity-dependent Er3+ population in excited states.
Magnetic recording now dominates the data, video, and audio storage for both professional and consumer applications. The technology has improved immensely as understanding of the physics of recording and reproducing processes is gained. Advances in recording materials and processes for fabricating components, especially with the thin film media and heads, have contributed in a major way to extending the performance of magnetic recording technology into different industries. Some examples of magnetic thin films applicating for recording media and heads studied in Information Storage Research Centre of Shanghai Jiao Tong University are described.
High quality epitaxial YBa2Cu3O7-(delta) films prepared by d.c. magnetron sputtering are single crystalline containing mosaic blocks, the boundaries of which consist of arrays of dislocations piling up into walls. Low temperature oxygenation in the orthorhombic phase is carried out by pipe diffusion in the basal planes. An equation has been derived from the dislocation model of low angle tilting grain boundary which predicts a linear relationship between the oxygen increase 1-(delta) and t3/4, where t is the diffusion time. Two straight lines were established for oxygen anneal respectively at 300 degree(s)C and 350 degree(s)C and these verified the proposed model explicitly. From slops of these two straight lines, an activation energy of 1.18 eV for lattice diffusion of oxygen is obtained.
Surface emitting laser diodes (SELD) are characterized by the fact that light is emitted vertically from the surface of the chip. The hemispherical resonator consists of one spherical mirror and one flat mirror placed approximately at the center of curvature of the sphere. In the past, the InGaAsP/InP SELD with hemispherical etched mirror was demonstrated at 77K. The authors have made theoretical calculations, considering material losses, resonator losses and angle deviation from the axis of cavity. The theoretical calculations indicate that in the case of the cavity length L more than 10 micrometers , the InGaAsP/InP SELD with hemispherical resonator is featured by having lower threshold current density Jth than with plane parallel resonator and will be possible in room temperature cw operation by using R equals (root)R1 (DOT) R2 equals 0.75 (Jth is congruent to 80 KA/cm2) or R equals 0.9(Jth is congruent to 25 KA/cm2), L equals 50 micrometers , d equals 1 micrometers and B 1, R2 are reflectivities of planar and hemispherical mirrors separately, d is the active layer thickness and B is the angle deviation from axis of cavity.
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