Geometry optimization of unidirectional integrated ring laser

Ring lasers, evanescently coupled to an adjacent optical waveguide, are essential components for the upcoming generation of integrated sources. In an ideally symmetric resonator, emission occurs from the both clockwise and counter-clockwise directions, resulting in a potential waste of emitted optical power, while unidirectional emission has been reported in different configurations, for example when asymmetric external reflectivities are used for the coupling waveguide. In the integrated form, a common approach consists in the inserting an S-bend waveguide in the ring, in such a way that the field propagating in the direction that we want to suppress is reinjected in the other direction. The S-bend waveguide must be carefully designed to reduce optical losses and to ensure a sufficient suppression of the undesired field. Using 2D finite- difference time-domain simulations performed with Synopsys RSof

S-shaped waveguide-induced asymmetry between counter-propagating modes in a racetrack resonator

Ongoing progress in photonic integrated circuits necessitates the integration of semiconductor ring lasers (SRLs) with high performance and predictable behavior, which can be achieved when the symmetry of the SRL, which supports both clockwise and counterclockwise beam propagation, is unbalanced through loss mechanisms inside the resonator. In this work, numerical simulations were carried out on the symmetric layout of the racetrack resonator equipped with an asymmetric S-shaped internal waveguide. The simulations results were compared with the ones of analogue structures without internal waveguide showing the benefit induced by this additional element in term of the unidirectionality of the SRL

Integrated multi-band WSS: from design to performance evaluation

Modern day optical communications require ever-increasing bandwidths and capacity, in order to keep up with the growth of traffic and resource-intensive applications. This increase in network capacity can be achieved through the use of the residual capacity of current-day infrastructure, although this requires switching and routing devices capable of wide-band operation in multiple transmission windows. In this work, we describe the design principle, architecture, and performance simulation of a photonic integrated circuit (PIC) based multi-band WSS, which is envisioned to operate on the S+C+L windows. While the architecture is scalable to an arbitrary channel and port count, we showcase a 24-channel implementation deployed on the 400ZR standard, providing both the penalty evaluation through DSP simulations, as well as a footprint evaluation based on the components design

Simplex algorithm for band structure calculation of noncubic symmetry semiconductors: Application to III-nitride binaries and alloys

A set of software tools for the determination of the band structure of zinc-blende, wurtzite, 4H, and 6H semiconductors is presented. A state of the art implementation of the nonlocal empirical pseudopotential method has been coupled with a robust simplex algorithm for the optimization of the adjustable parameters of the model potentials. This computational core has been integrated with an array of Matlab functions, providing interactive functionalities for defining the initial guess of the atomic pseudopotentials, checking the convergence of the optimization process, plotting the resulting band structure, and computing detailed information about any local minimum. The results obtained for wurtzite-phase III-nitrides (ALN, GaN, InN) are presented as a relevant case study