Browsing by Author "Tien, CH"

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Design and fabrication of fiberlenses for optical recording applications
(2002-03-01)
Tien, CH
;
Lai, YC
;
Milster, TD
;
Shieh, HPD
;
光電工程學系
The novel design and fabrication of a microlens on the front end of a single-mode fiber is described. The beam quality and spot size for optical recording applications are analyzed. A hyperbolic-shaped microlens on a single-mode fiber with focused spot of 1/e(2) = 0.82 mum (x-direction) and 0.89 mum (y-direction) at similar to 145 mum working distance was achieved by a simple fabrication procedure.
Double-corrugated C-shaped aperture for near-field recording
(2006-02-01)
Chen, YC
;
Fang, JY
;
Tien, CH
;
Shieh, HPD
;
光電工程學系
We applied surface corrugations surrounding the C-aperture on both incident and exit interfaces of the metal film, which can generate surface plasmon (SP) waves coupling to the propagation mode and function as a focusing grating, respectively. Compared with a 60 nm square aperture, the double-corrugated C-aperture can enhance power throughput by five orders of magnitude and reduce spot area by 30%.
Effects of aperture wall on the readout signal of erasable thermal phase change super resolution (EPSR) disks
(1999-03-01)
Liu, JR
;
Lu, YS
;
Tien, CH
;
Tang, NY
;
Shieh, HPD
A "below-diffraction-limited" aperture within the readout spot for high-density recording can be achieved on erasable thermal phase change super resolution (EPSR) disks. Compared to the large aperture wall formed by the DC detection method, the small aperture wall formed by pulse readout can not only increase the signal amplitude, but also suppress readout noise when detecting the EPSR disks. The small aperture wall width generated by pulse readout in the EPSR disk resulted in an 8 dB higher in carrier-to-noise (CNR) than that by DC readout in the conventional single-recording-layer phase change disk when reading the below-diffraction-limited marks of 0.4 mu m.
Fiber-lens-based module for optical recording applications
(2003-07-01)
Tien, CH
;
Chou, HL
;
Chiu, Y
;
Hsu, W
;
Milster, TD
An optical fiber-lens-type pickup with numerical aperture (NA) congruent to 0.27 was demonstrated for thermal recording of continuous 1.6-mum-wide lines on MO disks with 50% throughput efficiency. Moreover, a Si-micromachined near-field module integrated with a fiber lens, solid immersion lens (SIL), and submicron aperture was fabricated to improve the mechanical fragility and increase the NA of the optical-fiber-based pickup. The preliminary configuration design and measurement suggest the feasibility of the module as a submicron heat source for high-density optical data storage.
High-transmission hybrid-effect-assisted nanoaperture
(2006-03-01)
Chen, YC
;
Fang, JY
;
Tien, CH
;
Shieh, HPD
;
光電工程學系
We present a C-aperture encircled by a groove that makes possible the hybrid effect of coupling surface plasmen resonance to propagating waves. Compared to a single C aperture, the groove-encircled aperture can increase transmission by a factor of 2.45 in the near field and by a factor of 1.88 in the far field, showing good agreement with our theoretical calculation. (c) 2006 Optical Society of America.
Microlens array fabricated by excimer laser micromachining with gray-tone photolithography
(2003-03-01)
Tien, CH
;
Chien, YE
;
Chiu, Y
;
Shieh, HPD
;
光電工程學系
We demonstrate the fabrication of a refractive microlens array by using 249nm excimer laser micromachining with coded gray-tone mask photolithography. With pre-corrections to the nonlinear exposure process, the maximum deviation from the designed shape was below 5%. The fabricated hemispherical lens of 30 mum radius was used as a solid immersion lens (SIL) and combined with a 0.54 numerical aperture (NA) objective to achieve a 0.87 effective NA through the knife-edge scanning test. The. experimental results agreed with those of the simulation. Unlike the methods such as the thermal melting process, this one-step optical exposure method with a coded mask provides a relatively fast and cost-effective way to realize a microlens array in optical data storage, information processing, and optical interconnection applications.
Optical properties of surface micromachining with randomly distributed etch holes
(2006-02-01)
Tien, CH
;
Lee, CH
;
光電工程學系
;
顯示科技研究所
;
Department of Photonics
Optical micromachining or microelectromechanical systems (MEMS) typically require etch holes to reduce the time required to release the micromechanical structure during the sacrificial undercutting. However, high-order diffraction beams generated by the periodic etch-hole array often deteriorate the optical performance by generating noise and erroneous crosstalk signals in. most optical systems. In this study, we examined the diffraction from a perforated micromirror and proposed a random distributed etch-hole layout. Due to the superposition of cosine functions with random periods, noise caused by high-order beams can be averaged effectively.
Polarization analyses of readout signals by a solid immersion lens in phase change recording material
(2001-10-01)
Tien, CH
;
Lai, YC
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
Comprehensive analyses based on the rigorous vector diffraction theory were used to simulate the polarized readout signals using a solid immersion lens (SIL) in reading phase change (PC) disks. For an x-polarized incident beam, the signal contrast in x and y polarization was a different function of air gap between the bottom surface of the SIL and recording medium. Compared with conventional nonpolarized detection schemes for PC media, the x-polarized contrast is a factor 1.0 to 1.35 higher at different air gaps, at a small cost of total intensity loss. (C) 2001 Society of Photo-Optical Instrumentation Engineers.
Polarization analyses of readout signals in phase change material incorporating a Solid Immersion Lens (SIL)
(2000)
Tien, CH
;
Lai, YC
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
Comprehensive analyses based on rigorous vector diffraction theory have been presented to simulate the readout signal contrast using SIL in reading phase change recording disk. De-polarized reflected light (y-polarized from x-polarized incident beam) results in the reduction of total signal contrast, and becomes more obvious for high numerical aperture (NA) systems. Due to the signal degradation from de-polarized reflected light, filtering de-polarized light is applied to signal detection. The x-polarized contrast is a factor 1.0 to 1.35 higher than the conventional detection contrast (x+y polarized) at different gap widths, at a cost of 0 to 25 percent total intensity reduction.
Silicon-nitride based micro optical components for optical pickup application
(2005)
Lee, CH
;
Yi, C
;
Tien, CH
;
Shieh, HPD
;
光電工程學系
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%.
Thermal writing by long working distance Fiberlenses for Optical Recording Applications
(2002)
Tien, CH
;
Milster, TD
;
Chiu, Y
;
Shieh, HPD
;
光電工程學系