Elliptical Birefringent Rib‐Channel Chirowaveguides for Quasicircularly Polarized Light Applications in Integrated Photonics

Abstract

Polarization in photonic‐integrated circuits (PICs) is governed by transverse electric (TE) and magnetic (TM) polarizations due to the planar structure of the chips. Therefore, all states of polarization (SOPs) other than TE and TM, in particular circular polarization, cannot be routed without modification across the chips. Herein, the realization of rib‐channel chirowaveguides supporting elliptically polarized guided modes by combining linear and circular birefringences as predicted by the coupled mode approach is shown. The sol–gel process and the imprint technique to make channel chirowaveguides with different sizes and consequently modulate ellipticity of the eigenmodes from linear to quasicircular are used. Circularly polarized light propagates therefore with a low polarization beating and in particular without handedness inversion. These results open the field of application of PICs to all domains where circularly polarized light is relevant.

Effect of Humidity on of Sol-Gel Glass Chirowaveguide Thin Films and Microstructures

“…In our previous study, single-mode chirowaveguides have been characterized as elliptical birefringent devices. The degree of their polarization ellipticity is governed by the interplay between circular and linear birefringence [4]. In all our measurements, we never observed any dichroisms.…”

Collimating the growth of twisted crystals of achiral compounds

“…To test waveguiding in our materials, we must switch from making optical chiroptical measurements of banded spherulites normal to the radial growth direction 22,34,55 to make measurements along the radial growth direction, for example as in Scheme 2 53 . We have previously shown that the CR directed along twisted fibrils of polymers can be especially high at the very center of the polycrystalline ensemble where the fibers are parallel to the wavevector of light 56 .…”

“…Optical fibers conventionally transmit linear polarization as transverse electric (TE) and transverse magnetic (TM) modes 41 . Waveguiding with circularly polarized modes is attractive for a variety of applications 50 and can be achieved with a chiral medium 51–53 . Though likely only marginally relevant to spherulitic growth of molecular crystals, helically twisted photonic bundles of silica fibers exploit their dissymmetry to control the orbital angular momentum of light 54 …”

“…41 Waveguiding with circularly polarized modes is attractive for a variety of applications 50 and can be achieved with a chiral medium. [51][52][53] Though likely only marginally relevant to spherulitic growth of molecular crystals, helically twisted photonic bundles of silica fibers exploit their dissymmetry to control the orbital angular momentum of light. 54 To test waveguiding in our materials, we must switch from making optical chiroptical measurements of banded spherulites normal to the radial growth direction 22,34,55 to make measurements along the radial growth direction, for example as in Scheme 2.…”

Optical Study of Humidity Effect on Sol-Gel Glass Chirowaveguide Thin Films and Microstructures

“…We have developed the synthesis of a chiral ormosil precursor composed of an enantiopure binaphthyl unit covalently connected to a trialkoxysilane. Highly concentrated sols of this precursor in organic solvents, like dichloromethane or tetrahydrofuran, with PEG200 as an anti-cracking agent, can be coated as a thin film [2,3] and even micro-structured to produce rib optical waveguides [4]. The chirality of the gels introduces circular birefringence (CB) in the optical waveguides, leading to the formation of chirowaveguides [5].…”