Browsing by Author "Sheu, Lih-Gen"

Now showing 1 - 7 of 7

All-Optical Gain-Clamped Erbium-Doped Fiber Amplifier Using a DWDM Demultiplexer
(2009-01-01)
Huang, Ting-Tsan
;
Sheu, Lih-Gen
;
Chi, Sien
;
光電工程學系
;
Department of Photonics
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.
Fabrication of complex fiber grating structures by use of sequential writing with polarization control
(2005-07-14)
Chuang, Kai-Ping
;
Sheu, Lih-Gen
;
Tsai, Meng-Chang
;
Lai, Yinchieh
The present invention provides a fabrication method of complex fiber grating structures that can be combined with prior fabrication methods including a phasemask or a two-beam interferometer. By using a rotatable half-wave plate with a polarization beam splitter in the optical path and precisely scanning the relative fiber position, we can expose true complex fiber gratings in a single scan by simultaneously rotating the angle of the half-wave plate.
Fabrication of true apodized fiber bragg grating using a new two-beam interferometer with polarization control
(2005-07-14)
Chuang, Kai-Ping
;
Sheu, Lih-Gen
;
Tsai, Meng-Chang
;
Lai, Yinchieh
The present invention provides a two-beam interference exposure system that can be simply adjusted by rotating only one mirror. By placing a half-wave plate in one of the interference arms and precisely scanning the relative fiber position, the present invention can expose true apodized fiber Bragg gratings in a single scan by simultaneously rotating the angle of the half-wave plate. By rotationally switching the fast and slow axes of the half-wave plate, the present invention can also expose n-phase-shifted fiber grating by the same system.
Measurement of multi-wavelength optical amplifier by using the I/O power-curve fitting technique
(2009-06-15)
Huang, Ting-Tsan
;
Sheu, Lih-Gen
;
Chi, Sien
;
光電工程學系
;
Department of Photonics
A low-cost and accurate measurement scheme for characterizing multi-wavelength optical amplifiers is experimentally demonstrated by using an amplified spontaneous emission source and a DWDM multiplexer. By linearly fitting the input and output optical spectral densities, the gain and noise figure of the optical amplifier are determined. The measured results agree well with the data obtained by time-domain-extinction method. (C) 2009 Elsevier B.V. All rights reserved.
Method for sequentially writing fiber bragg grating by using real-time side-diffraction optical fiber position monitoring
(2006-11-23)
Hsu, Kuei-Chu
;
Sheu, Lih-Gen
;
Chuang, Kai-Ping
;
Chang, Shu-Hui
;
Lai, Yinchieh
The present invention provides a fiber Bragg Grating sequential writing method with real-time optical fiber position monitoring, characterized in that the relative phase between a fiber grating and a writing interference beam at each positioning point is determined by an interferometric side-diffraction method, and writing is sequentially performed. Accuracy in fabricating a long and complex fiber grating structure can be increased by decreasing or avoiding accumulative errors caused by long-term scan of monitoring optical fiber position, or by a means for fabricating a wanted reference fiber Bragg grating with similar settings.
Methods of achieving linear index-change response for narrow-band fiber Bragg grating sequential writing
(2007-09-15)
Hsu, Kuei-Chu
;
Sheu, Lih-Gen
;
Hsiang, Wei-Wei
;
Lai, Yinchieh
;
光電工程學系
This investigation elucidates the refractive index-change response of the photosensitive optical fiber to exposed UV flux. The nonlinear U-V photosensitivity deforms the index profile of FBGs on the tail edges where the writing UV flux is low. Pre-UV treatment eliminates the nonlinear index-change response and ensures the linearity of the response of subsequent grating writing. A new method that involves interference between two unequal beams in a single writing scan is proposed and demonstrated to be able to improve the index profile and the spectral response of fabricated FBGs. The procedure is stable for writing weak fiber Bragg gratings with pre-designed index profiles. (c) 2007 Elsevier B.V. All rights reserved.
Optical power equalization for upstream traffic with injection-locked Fabry-Perot lasers in TDM-PON
(2010-10-15)
Huang, Ting-Tsan
;
Sheu, Lih-Gen
;
Chi, Sien
;
光電工程學系
;
Department of Photonics
An optical power equalization of upstream traffic in time-division-multiplexed passive optical network (TDM-PON) based on injection-locked Fabry-Perot lasers has been experimentally investigated. The upstream transmitters with stable spectrum are achieved by using an external injection light source in the optical line terminal (OLT). The different upstream powers can be equalized by injection locking a Fabry-Perot laser diode (FP-LD) biased below threshold current in OLT. The dynamic upstream power range from -8.5 to -19.5 db m is reduced to a 1.6 dB maximal power variation, when the uplink signal is directly modulated at 1.25 Gb/s. (C) 2010 Elsevier B.V. All rights reserved.