Power-conserving generation of arbitrary spatial photonic states

Active photonic state generators are fundamental components in the prototyping and testing of photonics integrated circuits (PICs). Although instruments offer solutions for optical switching, which is enough for PIC transmission characterization, some PICs exploit the analog nature of light and require specific complex photonic states to perform the intended operations, such as convolutional accelerators [1].

This work introduces and experimentally validates a compact and low-cost arbitrary photonic state generator component. The proposed solution is based on a multilayer architecture [2,3] comprising passive mixing waveguide arrays that create constructive interference by tuning active phase control elements. Numerical and experimental results validate that arbitrary states can be generated with a minimum number of two layers, regardless of the total number of ports. This poses an advantage compared to other solutions based on Mach-Zehnder interferometers, where the footprint scales in both dimensions according to the total number of ports. Furthermore, because of the unitary nature of the proposed architecture, light routing and distribution are achieved in a lossless manner, and no power leakage is required to target the desired photonic states. This paves the way for highly energy-efficient PIC control units.

[1] K Zelaya, MA Miri, Photonics Research 12 (8), 1828 (2024)

[2] M Markowitz, K Zelaya, MA Miri, PRA 110 (3), 033501 (2024)

[3] K Zelaya, M Markowitz, MA Miri, Sci. Reps. 14 (1), 10950 (2024)