Dedi Irawan

Linear and triangle order of NX3 optical directional couplers: Variation coupling coefficient

Fabrication of single-mode fiber coupler has widely expands. However, directional fiber coupler geometry always affects the power propagation either two or three ports. This paper describes power launching by NX3 single mode fiber, examined using a matrix transfer for linear and triangle order, calculated from the eigenvalue and the eigenvector. This eigenvalue is referred to the coupling coefficient, where it can be expressed as an effective power transmitted to another fiber. The ratio of coupling coefficient between adjacent axial fibers varies, which can be achieved by adjusting separation of fiber and refractive index of core and cladding. A calculation has been shown in 3D that both power transmission and phase are affected by not only the geometry order, but also the variation of coupling coefficient, assuming the propagation constants, cross section, and separation of coupling length fiber axis are held constant. This calculation can be applied for any sources of wavelength and junction.

Modification of Coupling Power Parameters for High Accuracy Coupling Ratio of Weakly Coupled Fiber

The directional fiber couplers consist of multi fibers joint have been successfully fabricated by heating of torch flame at atmospheric pressure and pulling the fiber coupling region mechanically at micro scale. Good performance of the coupling coefficient and the coupling ratio was obtained by setting the initial parameter of coupler machine such as the coupling coefficient, pulling speed, pulling length, coupling ratio, Hidrogen gas flow and pressure and heating temperature during process. The Coupling coefficient of 3-dB fused directional fiber coupler was determined based on perturbation method and coupling mode. A good agreement between theoretical purposed and empirical coupling coefficient from experimental result was reported. The coupling coefficient between the waveguides is significantly induced by the distance of axial separation between parallel fibers and geometrical coupling region. It is exponentially decreases by increasing separation between fibers. However, by controlling the coupling coefficient, the desired coupling ratio can be easily attained.

Theoretical improvement of coupling parameters directional fiber coupler using Bessel function

We have investigated the optimum parameter to fabricate multi fiber of silica material for directional coupler based on fusion and elongation techniques. Coupling coefficient between the fibers was derived by using Bessel function. 476 Dedi Irawan et al. However, the fusion temperature was experimentally determined as function of elongation speed. Good performance of multi fiber coupler has been obtained for fabrication parameters of fusion temperature and elongation speed of 1350 C and 125 μm/s respectively. The proposed coupling coefficient shows a better accuracy with empirical one for various coupling length. It is exponentially increased by reducing the distance between fibers. Finally, the microscopic analysis of coupling region deformation has shown that the silica material was well dispersed and distributed.

Investigation of noise effects of CMS laser lineshape and frequency fluctuations

Lineshape and frequency fluctuations actually cause the optical field of current modulation semiconductor laser (CMS) laser beam to deviate from a pure sine wave [1]. This paper investigates the lineshape of a CMS laser for two distinct types of frequency noise. In the first case the investigation analyzes on the low-pass filter, the frequency noise level is a constant δo below a cutoff frequency but zero above this threshold. In the second case on high-pass filter the frequency noise level is a constant δo above a cutoff frequency but zero below this threshold. Investigations observed inspire us to focus for separation of the frequency noise spectrum into two regions wherein due to the effect of noise on the lineshape is radically different in the slow modulation area in a left side of the diagonal line where the noise contributes to the laser linewidth, with a Gaussian shape, and the other one the fast modulation area in a right side of the diagonal line, where the noise contributes only to the wings of the line (sidebands) and not to the linewidth, thus transforming the lineshape from Gaussian to Lorentzian.