TE/TM mode splitters on InGaAsP/InP

Abstract

In a monolithic heterodyne polarization diversity receiver, mode splitters which effectively separate the TE and TM polarization of the optical wave are required. For this purpose, a directional coupler which utilizes a metal cladding on one of its branches to separate both polarizations was investigated. The polarization splitters can act in two distinct modes of operation, depending on the degree of lateral confinement of the optical rib waveguide before an asymmetric coupler. For weak confinement, the metallized waveguide is guiding for TE- but nonguiding for TM-polarization, and negligible TM-crosstalk results

Ultrasmall integrated devices based on silicon nanowires for optical communications

“…This usually makes the channel spacing polarizationdependent in a conventional AWG (based on Si nanowires). Therefore, the polarization compensation methods for an AWG based on micrometric waveguides [52,53] which can only compensate the polarization sensitivity of the central channel wavelength, are not suitable for an AWG based on Si nanowires. We have given a design of polarizationinsensitive Si-nanowire-based AWG by carefully choosing the geometrical parameters of the arrayed waveguides and the FPRs [45].…”

Mach-Zehnder interferometer polarization splitter in InGaAsP/InP

“…A metal layer applied directly on top of a ridge waveguide causes a very strong reduction in the TM effective index [6], with a small decrease in the TE effective index and a large attenuation for both polarizations. The inclusion of a (low-index) dielectric layer between the waveguide and the metal can compensate the TE index decrease and bring the propagation losses to acceptable levels [9], while still The red and imaginary part of the effective indices were calculated for both by using the Effective Index Method with complex refractive indices for the metal layers [lo].…”

“…The polarization-dependent phase shift in a pair of length-compensated nitride-loaded silicon-based waveguides was exploited in an interferometer polarization splitter [5]. Polarization splitters based on metal-cladded directional couplers in InGaAsPDnP were demonstrated [6]. More recently, a mode evolution splitter has been reported [7] which exploits the large birefringence of first-order modes in ridge waveguides.…”

Design of a Compact Polarization Splitter by Using Identical Coupled Silicon Nanowires

“…Small material birefringence of GaAs was exploited to design a 3000 m long PS [9]. Metal clad can introduce strong modal birefringence and Albrecht et al reported a 1600 m long metal clad InP rib waveguide based asymmetrical directional coupler [10] and later on Rajarajan et al reported a more compact 230 m PS [11]. On the other hand, silicon waveguide can directly provide stronger shape birefringence Kiyat et al reported an even more compact 120 m PS using silicon rib waveguide [12].…”