Multilevel asymmetric coupler MAC field rotator for LP11 mode in few mode fiber

Abstract

In this work, we present a new design for an integrated optical field rotator for the mode LP11a to the mode LP11b and vice versa using planar Silica over silicon technology. The structure is designed using a Multilayer Asymmetric Coupler. The coupling efficiency of the coupler could be as high as 99% when its length is about 1 mm. For a shorter coupler of length 550 microns and a coupling efficiency of 91%, a complete structure is designed to couple 2 few mode fibers of diameters 15.4 microns through an inverted taper from one side and a Y junction with two inverted tapers from the other side. The fiber to fiber insertion loss of the proposed structure is less than 3 dB over about 190 nm spectral range around 1550 nm. The 3 dB bandwidth of the structure is greater than 360 nm as demonstrated by the Beam Propagation Method BPM simulation.

Optical coupling into deeply etched Si waveguide

“…We may identify 3 different depths for the grating region, waveguide WGa and waveguide WGb. These different depths are now available through the Multi-level technology that uses different Si etching depths [11][12][13]. The dimensions of waveguides WGa and WGb are illustrated in table 1.…”

Investigating changes in the electric field profiles of transverse modes in fibres due to bending

“…Prior to this, reports have been presented in the field of the electric field of beams inside fibres, encompassing spatial distribution of the mode fields of both straight and bent fibres. Additionally, valuable experimental and theoretical works on this subject, including the analysis of beam modes, have been published [25][26][27][28][29][30][31]. Also, due to reasons such as microscopic bends, voids and cracks, the variation in the diameter and density fluctuation, the transition from one mode to another mode during propagation in the fibre is possible.…”