Author(s): Lu, ZQ (Lu, Ziqing); Han, Q (Han, Qin); Ye, H (Ye, Han); Wang, S (Wang, Shuai); Xiao, F (Xiao, Feng)

Source: PHOTONICS Volume: 7 Issue: 2 Article Number: 26 DOI: 10.3390/photonics7020026 Published: JUN 2020

Abstract: An optical 90 degrees hybrid based on an InGaAsP/InP deep-ridged 4 x 4 multimode interference (MMI) coupler is proposed and fabricated. Manufacturing tolerances on structural parameters of the 90 degrees hybrid including multimode waveguide width and length, waveguide core thickness, and refractive index are analyzed over the whole C-band using a three-dimensional beam propagation method (3D BPM). The simulation results show that the 90 degrees hybrid is insensitive to the interference length with a deviation of 10 mu m. However, the width fluctuations produce far stronger performance variations than length fluctuations. The common-mode rejection ratios (CMRRs) are always above 40 dB, and the phase error (PE) is always below 2.5 degrees with the fluctuations of the refractive index by 0.01 and the thickness by 0.1 mu m of the core layer. The fabricated device exhibited a quadrature phase response with a high common-mode rejection ratio of more than 25 dB and a small phase error of less than 5 degrees from 1545 nm to 1560 nm.

Accession Number: WOS:000551229300008

eISSN: 2304-6732

Full Text: https://www.mdpi.com/2304-6732/7/2/26