ORIGINAL PAPER Ultra-short novel transverse magnetic to transverse electric polarization rotator in hybrid integration of InGaAsP/silicon-on-insulator technologies M Nikoufard* and M Hatami Department of Electronics, Faculty of Electrical and Computer Engineering, University of Kashan, 87317-51167 Kashan, Iran Received: 25 January 2015 / Accepted: 14 May 2015 / Published online: 8 July 2015 Abstract: This article describes a full-vectorial two- and three-dimensional analysis of a novel polarization rotator (transverse magnetic to transverse electric polarization) using the finite element method. The core, substrate, and cladding of the polarization rotator are InGaAsP, SiO 2 , and SiO 2 /air materials, respectively, suitable in an InP-based membrane technology. The effects of several parameters such as refractive index of core, the ratio of the width to height of the polarization rotator, and wavelength of incident light on the rotation angle, polarization conversion length, and polarization conversion efficiency are investigated. The simulation results show that the rotation length is \ 1 lm at 1.55 lm wave- length and a maximum rotation of 89° can be achieved to have a linear polarization at the output end of polarization rotator. Keywords: Polarization rotator; Polarization converter; Triangular waveguide; Finite element method; Full-vectorial analysis PACS No.: 42.82.-m 1. Introduction Silicon technology has been developed for a few decades to very large-scale integrated (VLSI) electronic circuits. This technology has the disability of the fabrication of optical sources due to the indirect bandgap of silicon [1]. Mean- while, InP-based technology benefits using direct bandgap materials at 1.55-lm wavelength window. Hybrid inte- gration of InP and silicon-on-insulator (SOI) technologies can present very compact devices [2, 3]. For a decade, the technology of InP-membrane-on-silicon (IMOS) has got attention of researchers in some photonic laboratories [4]. Several very compact active and passive devices such as photodetectors [5], lasers [6], and polarization converters (PCs) [7] based on these technologies have been fabricated. PCs are required in communication system receivers which are sensitive to the transverse electric (TE) and transverse magnetic (TM) polarizations. In such systems, the polarization of incident light can be changed in the passive or active devices which are monolithically integrated with lasers or photodetectors. Besides, each wavelength can be utilized twice for both TE and TM polarization states in an optical transmitter [8, 9]. PC is a device which converts the TE polarization light into the TM light and vice versa [10]. Various PCs have been reported on semi-insulating insulator (SOI) and InP platforms with different configurations of the periodic asymmetric loaded waveguide [8], slanted sidewall [11], and asymmetric cross-sectional bend waveguide [12]. An ultra-short PC with the sloped sidewall of 45° and a 2-lm- long device has been proposed [13] which is highly sen- sitive to the sloped sidewall angle. The polarization rotation behavior is determined by the imaginary-distance beam-propagation method (BPM) and finite-difference time-domain (FDTD) method on SOI technology at 1.55 lm wavelength [13]. Recently, an ultra- short PC in InP membrane with a total length of 7.5 lm long has been fabricated with high tolerance to the fabrication errors due to the use of wet chemical etch to create a 35° angled sidewall with respect to the crystallographic plane of (001) [4]. So far, the full-vectorial beam-propagation method [14], film mode-matching (FMM) [4], and FDTD [15] have been *Corresponding author, E-mail: mnik@kashanu.ac.ir Indian J Phys (February 2016) 90(2):211–217 DOI 10.1007/s12648-015-0724-6 Ó 2015 IACS