Shih-Chiang Lin

NUMERICAL ANALYSIS OF APODIZED FIBER BRAGG GRATINGS USING COUPLED MODE THEORY

In this paper, the coupled mode theory is used to analyze apodized fiber Bragg gratings (FBGs). Since the profile of gratings varies with the propagation distance, the coupled mode equations (CMEs) of apodized FBGs are solved by the fourth-order Runge-Kutta method (RKM) and piecewise-uniform approach (PUA). We present two discretization techniques of PUA to analyze the apodization profile of gratings. A uniform profile FBG can be expressed as a system Corresponding author: H.-W. Chang (hchang@faculty.nsysu.edu.tw).

A New Look at Numerical Analysis of Uniform Fiber Bragg Gratings Using Coupled Mode Theory

The coupled mode theory (CMT) is used to analyze uniform Fiber Bragg gratings. The multi-mode CMT is expressed as the flrst-order vector ordinary difierential equations (ODEs) with coe-cients depending on the propagation distance. We show in this paper that by changing variables, the original couple mode equations (CMEs) can be re-casted as constant coe-cient ODEs. The eigenvalue and eigenvector technique (EVVT), the analytic method for solving constant coe-cient ODEs, is then applied to solve the coupled mode equations. Furthermore, we also investigate the application of Runge- Kutta method (RKM) to the calculation of the global transfer-function matrix for CMEs. We compare the transmission and the re∞ection

Analysis of an Ultrashort PCF-Based Polarization Splitter

We propose a new structure of polarization splitter based on a dual-elliptical-core photonic crystal fiber. The polarization splitter has a simple and symmetric directional coupler configuration. The vector boundary element method is used to investigate the propagation characteristics of the device under various conditions. Results of the numerical calculation relevant to the design conditions are presented. A 0.3-mm-long splitter with an extinction ratio of 23 dB is obtained.

Second-order fiber Bragg gratings

In this paper second-order fiber Bragg gratings are firstly experimentally demonstrated to have the characteristic of surface-normal radiation confirmed by measuring the radiation power of 0.012mW from the 2D far-field pattern.

Enhanced cascade ξ (2) SHG+DFG interactions based on chirp period quasi-phase-matched waveguide

A theoretic study about a 170% conversion efficiency enhancement of cascade chi(2) SHG+DFG interactions by using a chirp period quasi-phase-matched waveguide.

Enhanced Cascaded SHG+DFG Process of Femtosecond Pulses Using Chirp Quasi-Phase Matching Waveguide

This study presents a chirp quasi-phase matching (QPM) waveguide to increase the conversion efficiency of the cascaded SHG+DFG effect for femtosecond pulses. The coupled mode theory is used to analyze the cascaded SHG+DFG process. In this paper, a constructive interference zone (or cascaded SHG+DFG region) is defined as when the conversion wave and its coupling component constructively interfere with each other and have a phase difference ranging from 0 to 0.5pi or from 1.5 to 2pi. On the other hand, the region is called a destructive interference zone (or back conversion region) when the phase difference ranges from 0.5 to 1.5pi . The proposed chirp QPM waveguide is designed to extend constructive interference length and shorten destructive interference length over the waveguide. The simulation results demonstrate that for a pulsewidth of 0.6 ps, the maximum conversion efficiency of a 50-mm chirp QPM waveguide can be increased to 25 times that of a uniform QPM waveguide.

Phase dependent second-order fiber Bragg gratings

The phase dependent properties of a second-order FBG are presented. At the second Bragg condition, the radiated power of the second-order FBG varies by a factor of 2.4 as the phase changes by % radians.

Grating-Outcoupled Radiation in Second-Order Fiber Bragg Gratings

Abstract The experimental results of the radiation for second-order fiber Bragg gratings, which are made of a single-mode photosensitive fiber (PS-1500; Fiber-Core Corp.) and a single-mode fiber (SMF-28; Corning Inc.), by a phase mask writing fabrication technique are explored. For PS-1500 fiber Bragg gratings, the maximum radiation efficiency of −23.5 dB at resonance λ = 1,539.34 nm with a very narrow bandwidth (about 0.02 nm) are measured from a 10-mm-diameter photo-detector, while for SMF-28 fiber Bragg gratings, the maximum radiation efficiency is −34.6 dB (λ = 1,538.03 nm) with a bandwidth of 0.06 nm. The total efficiencies of the radiation are about −16.8 dB for PS-1500 fiber Bragg gratings and −28.1 dB for SMF-28 fiber Bragg gratings.

Phase dependent of DBR gratings

A novel double input DBR grating is presented in this paper. The length of the grating region and the phase difference of the inputs can determine the direction and the efficiency of the output power.th of the grating region and the phase difference of the inputs can determine the direction and the efficiency of the output power.

A novel approach for modal analysis of terahertz photonic crystal fibers

Vector boundary element method is proposed to analyze the guided modes of terahertz photonic crystal fibers. The results are evaluated the fundamental mode and high-order mode field distribution for terahertz photonic crystal fiber.