Ultrafast perturbation maps as a quantitative tool for testing of multi-port photonic devices

Kevin Vynck,Bigeng Chen,David J Thomson,Graham T Reed,Nicholas J Dinsdale,Philippe Lalanne,Roman Bruck,Ali Z Khokhar,Otto L Muskens,Lee Crudgington,Scott A Reynolds

doi:10.1038/s41467-018-04662-2

Abstract

Advanced photonic probing techniques are of great importance for the development of non-contact wafer-scale testing of photonic chips. Ultrafast photomodulation has been identified as a powerful new tool capable of remotely mapping photonic devices through a scanning perturbation. Here, we develop photomodulation maps into a quantitative technique through a general and rigorous method based on Lorentz reciprocity that allows the prediction of transmittance perturbation maps for arbitrary linear photonic systems with great accuracy and minimal computational cost. Excellent agreement is obtained between predicted and experimental maps of various optical multimode-interference devices, thereby allowing direct comparison of a device under test with a physical model of an ideal design structure. In addition to constituting a promising route for optical testing in photonics manufacturing, ultrafast perturbation mapping may be used for design optimization of photonic structures with reconfigurable functionalities.

Highlights

Advanced photonic probing techniques are of great importance for the development of noncontact wafer-scale testing of photonic chips
The most advanced tools for characterization of photonic devices rely on the use of a scanning perturbation placed in the near-field of the structure to infer information on the electromagnetic fields propagating within it[5]
ultrafast photomodulation spectroscopy (UPMS) measures the impact of a local refractive index variation, created by ultrafast excitation of free carriers in the semiconductor material, on the transmittance between two ports of a photonic structure at a given frequency

Summary

Introduction

Advanced photonic probing techniques are of great importance for the development of noncontact wafer-scale testing of photonic chips. Near-field optical techniques can provide very high resolution information on electromagnetic fields and are excellent research tools for detailed studies of new concepts. Their use in an industrial environment is less obvious due to the complexity of the nanoprobes and the requirement of near-field access. A new technique, named ultrafast photomodulation spectroscopy (UPMS), that allows the remote optical characterization of photonic devices was introduced[6]. A direct numerical resolution of the electromagnetic problem is not a viable strategy since, besides not bringing much physical insight, one should repeat the simulations as many times as the number of perturbation positions It becomes a very computationally heavy task for large photonic devices

Methods

Results

Conclusion