Optimal design of error-tolerant reprogrammable multiport interferometers

Abstract

Photonic information processing often demands programmable multiport interferometers capable of implementing arbitrary transfer matrices, for which planar meshes of tunable Mach-Zehnder interferometers (MZIs) are usually exploited. However, these MZI-based interferometers require balanced static beam-splitter (BSs) that make them sensitive to manufacturing errors. Here, we abandon the error-sensitive MZI and propose an alternative design that uses a single static BS and a variable phase shift as the building block of the interferometer mesh. Our BS-based design has been shown to possess superior resilience to manufacturing errors, which is achieved without addition of extra elements into the schemes. Namely, the power transmissivities of the static BSs constituent the interferometers can take arbitrary values in the range from ≈ 1/2 to ≈ 4/5.

Stability of Self-Configuring Large Multiport Interferometers

“…This may lead to a fundamental limit on size, closely tied to the transition between ballistic and diffusive transport of light [20]. For such extreme sizes, entirely new crossing designs [21] or mesh architectures [25][26][27][28]38] may be required.…”

“…In both cases, the circuit can be laid out on a regular grid of 2 × 2 elements (Fig. 1(a)) without any waveguide crossings, a major advantage compared to competing designs [25][26][27][28]. The input-output matrix of the mesh is accordingly a product:…”

Emergence of biased errors in imperfect photonic circuits

“…Pioneering work in this scope was done by Miller, who proposed solutions for automatic alignment, configuration and compensation 28 . Recent works have focused on various other approaches, including numerical techniques 25,29,30 , port allocation and compilation 31 , and architecture refinements 25,[32][33][34] . Our analysis addresses issues related to error propagation in photonic circuits, so that they can be better addressed by the above strategies.…”

Waveguide lattice based architecture for multichannel optical transformations

“…The established way of implementing programmable multichannel schemes exploits the lumped-parameter approach, in which the schemes come in the form of meshes of building blocks, each of which performs only single discrete function over a subset of channels. There exist several decomposition methods using this approach that enable construction of programmable photonic circuits capable of implementing a range of linear transformations covering all [13,14] or almost all possible [15,16] transfer matrices. Most often, the meshes' building blocks are the Mach-Zehnder interferometers (MZIs) [13,14].…”