arXiv subjects

Manuel Kohli

Publications and source records attributed to Manuel Kohli.

2 recordsLinked to original sources

arXiv2026

VCSEL-based CPO for Scale-Up in A.I. Datacenter. Status and Perspectives

The drastic increase of bandwidth demands in AI datacenters requires new solutions with low power consumption and high bandwidth densities. Further increasing the total bandwidth with copper interconnects is challenging, thus it is crucial to introduce optics into the scale-up network. For this purpose, the most important metrics are the energy efficiency of the total link in addition to the spatial bandwidth-density and reach. With the inefficiency of copper traces at high speeds, transitioning to co-packaged optics is no longer optional but essential. Here, we show that the mature VCSEL technology offers the ideal combination of low-cost, low-latency, high-reliability, and energy efficiency at all bitrates, thanks to their unique versatility and high wall-plug-efficiency. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.

physics.optics↗

arXiv2024

Barium Titanate and Lithium Niobate Permittivity and Pockels Coefficients from MHz to Sub-THz Frequencies

The Pockels effect is essential for controlling optical signals at the highest speeds, particularly for electro-optic modulators in photonic integrated circuits. Lithium niobate (LN) and barium titanate (BTO) are two excellent Pockels materials to this end. Here, we measure the Pockels coefficients and permittivity in LN and BTO over a continuous frequency range from 100 MHz to 330 GHz. These properties are constant across this frequency range in LN but have a significant frequency dependence in BTO. Still, our measurements show that BTO has remarkably large electro-optic properties compared to LN. Furthermore, we show how BTO devices can be designed with a flat electro-optic frequency response despite the Pockels coefficient dispersion. Finally, we expound our method for broadband characterization of these vital electro-optic properties, utilizing specialized integrated electro-optic phase shifters. Altogether, this work empowers the design of high-speed BTO devices and the development of new electro-optic materials.

physics.optics↗