Programmable Space-Frequency Linear Transformations in Photonic Interlacing Architectures

TL;DR

This paper demonstrates a programmable silicon photonic circuit capable of performing linear transformations in both space and frequency domains, enabling advanced wavelength routing and filtering applications.

Contribution

The authors introduce a novel space-frequency transformation architecture in programmable photonics, expanding capabilities beyond traditional spatial-only linear operations.

Findings

Successfully implemented space-frequency linear transformations

Demonstrated wavelength demultiplexing and filtering

Reconfigurable frequency-dependent matrix operations

Abstract

Programmable photonic circuits are versatile platforms that route light through multiple interference paths using reconfigurable optoelectronic elements to perform complex discrete linear operations. These circuits offer the potential for high-speed and low-power photonic information processing in various applications. The mainstream research on programmable photonics has focused on implementing linear operations on discrete signals encoded in the modal amplitudes of an array of spatially separated single-mode waveguides. However, many photonic device applications require simultaneous transformations in the space-frequency domain, where information is encoded in both the spatial modes of waveguides and their spectral content. Here, we experimentally demonstrate linear space-frequency transformations using a $4 \times 4$-port programmable silicon photonic circuit with an alternating architecture. This design leverages the limited dispersion of coupled waveguide arrays to enable linear operations with reconfigurable frequency-dependent matrix elements. We utilize this device to perform wavelength demultiplexing and filtering. This architecture platform can pave the way for versatile devices with applications ranging from wavelength routing to programmable dispersion control.