Based on a finite-conjugate objective lens with numerical aperture of 0.62 for a 650-nm wavelength, an optical pickup head composed of a multifunction beamsplitter and a diffractive optical element is designed be used in a swing-arm-type optical pickup head. The diffractive optical element is a lens with an elliptical four-level phase profile to provide both focusing and astigmatism. It is also designed with the goal to simplify the overall optical configuration and provide linear characteristics for the focus error signal.
A pop-up binary-phase micrograting and a pop-up micro polarization beamsplitter, for potential use in micro-optical pickups, have been realized on a single silicon chip using a two-layer polysilicon and one-layer silicon nitride micromachining process. In the case of the micrograting, a diffraction efficiency ratio between 4 and 10 can be achieved provided that the duty cycle is between 0.4 and 0.6 and the depth between 455 and 485 nm, respectively. For a grating designed for a diffraction ratio of 7, the measured ratio is 8.31. The polarization beamsplitter is a silicon nitride thin film placed at the Brewster angle. The transmittance of the TM mode was measured to be more than 98.5%, while the reflectance of the TE mode was 21.4%.
A stress-induced curved \micro actuator with a grating attached at the end is demonstrated for recordable optical
storage applications. The actuator and the grating were fabricated using a two-layer poly-silicon and one-layer silicon
nitride micro-machining process. Three diffracted beams with equal intensity from the grating were generated when a
voltage is applied to the actuator to switch its position. The single-beam and multi-beam configurations can be used for
writing and reading data in the disc, respectively.
A novel bidirectional 2×2 optical switch technique, based on the conventional erbium-doped fibers (EDFs) with an operation of pumped or unpumped power level, is proposed and demonstrated experimentally. By using the amplification and absorption function of EDFs and a simply architecture design, the input signals can be switched to a suitable position. The response time of wavelength switching will approach about 2 ms. Moreover, the behavior and system performance of the proposed configuration also have been studied.
The design and fabrication of micro gratings and polarization beam splitters for potential use in micro optical pickups are presented. Silicon nitride is used as the optical material for its low absorption in the visible wavelength. The micro components are framed by a pop-up poly-silicon mechanism as in the standard surface micromachining technology.
The micro grating is a binary phase grating. The diffraction ratio between 4 and 10 can be achieved provided that the duty cycle is between 0.4 and 0.6 and the depth between 455nm and 485nm. For a grating designed for a diffraction ratio of 7, the measured ratio is 8.31.The polarizing beam splitter is a silicon nitride thin film placed at the Brewster angle. The transmittance of the TM mode of a micro polarization beam splitter was measured to be more than 98.50%.