Lih-Gen Sheu

Diffuser array for a light-emitting diode backlight system

A novel light-emitting diode backlight module applied in liquid crystal displays is demonstrated. With microgrooves on the bottom surface and diffusive dots on the upper surface of the light guide plate (LGP), most of the incident backlight is utilized effectively and the dispersion of light is decreased obviously. The design procedure of optimization for the backlight module is accomplished by the TracePro optical simulation software. Relationship between the dimensions of microgrooves and diffusive dots are investigated and discussed in detail. By using the structure of microgrooves and diffusive dots on the LGP, the incident light satisfies the total internal reflection conditions and reflects from the bottom surface then spread by the diffusive dots. Compared to the conventional backlight devices, the light uniformity and light intensity for the LGP are improved by our design.

Phenomenon of hygroscopicity in a fiber fabry-Pérot interferometer with an absorbent polymer cavity

We experimentally measure the hygroscopicity of liquid by using ultracompact fiber Fabry-Pérot interferometers (FFPIs) with an absorbent polymer-microcavity in a hollow-core-fiber. Experimental results of adsorption and desorption behaviors show a hysteresis phenomenon during the processes.

Optical fiber design for slanted grating filters with narrow-band symmetric response

Analysis concerning slanted FBGs written in the designed fiber with various inner-cladding parameters is presented. The properties of slanted FBGs fabricated in a standard photosensitive-cladding fiber and in a special designed fiber are experimentally compared.

All-optical gain-clamped erbium-doped fiber amplifier using a DWDM demultiplexer

A simple gain-clamped erbium-doped fiber amplifier using a DWDM demultiplexer is proposed. The amplified DWDM signals are separately exported without the lasing power, while the low noise-figure is obtained.

The tunable dispersion of side-polished fiber Bragg gratings

The chromatic dispersion and polarization dispersion of a side-polished fiber Bragg grating encapsulated in a polymer-half-filled metal cylinder is experimentally demonstrated to have the tuning ability by adjusting the applied pressure.

Common-path interferometer for dispersion measurement of fiber Bragg gratings

A common-path-interference dispersion-measurement scheme for fiber Bragg gratings is experimentally demonstrated. The group delay is obtained by processing the interference spectrum and the results excellently match the data from an optical network analyzer.

Gain and Noise Figure Measurement for Optical Fiber Amplifiers by Using an ASE Source and DWDM Filters

We propose a low-cost scheme for characterizing optical amplifiers. By linearly fitting the input/output optical spectra measured with an ASE source and DWDM filters, the results excellently match the data obtained by the TDE method.

A simple dispersion measurement of fiber gratings by interferometric technique

A simple dispersion measurement of fiber gratings using an un-balanced Michelson interferometer is proposed. A broadband source and an optical spectrum analyzer are used to scan the interference spectrum, and then the group time delay can be obtained rapidly by Fourier transform processing the interference spectrum. We measured the group time delays of a uniform-period FBG, a chirped FBG, an arrayed-waveguide grating interleaver, and a thin-film filter type OADM by an un-balanced Michelson and Mach-Zehnder interferometers, respectively. The experimental results excellent match the measured results of the optical network analyzer. The experimental repeatability is shown to be better than 1ps.

Multi-channel dispersion compensating fiber grating by single-period overlap-step-scan exposure

We theoretically demonstrate a high-quality multi-channel dispersion-compensating fiber grating can be fabricated by a properly designed single-period overlap-step-scan exposure method. A practical design example and a detailed discussion of this new fabrication method are given.

Complex fiber grating structures fabricated by sequential writing with polarization control

We propose a flexible method for fabricating complex fiber grating structures based on the sequential writing for fiber gratings with the polarization control of the UV exposure beam. By simultaneously rotating the angle of the half-wave plate when the fiber is scanned, pure apodized as well as phase-shifted fiber gratings can be fabricated in a single scan. Experimental examples of raised-cosine /spl and/2 apodized and /spl pi/ phase-shifted fiber gratings are given to demonstrate the feasibility of this method.