Nanophotonic Pockels modulators on a silicon nitride platform (1805.05437v2)

Abstract: Silicon nitride (SiN) is emerging as a competitive platform for CMOS-compatible integrated photonics. However, active devices such as modulators are scarce and still lack in performance. Ideally, such a modulator should have a high bandwidth, good modulation efficiency, low loss, and cover a wide wavelength range. Here, we demonstrate the first electro-optic modulators based on ferroelectric lead zirconate titanate (PZT) films on SiN, in both the O- and the C-band. Bias-free operation, bandwidths beyond 33 GHz and data rates of 40 Gbps are shown, as well as low propagation losses ($\alpha\approx 1$ dB/cm). A $V_\pi L\approx$ 3.2 Vcm is measured. Simulations indicate that values below 2 Vcm are achievable. This approach offers a much-anticipated route towards high-performance phase modulators on SiN.

Nanophotonic Pockels Modulators on a Silicon Nitride Platform

This paper, authored by researchers from Ghent University, explores the development of electro-optic modulators using ferroelectric lead zirconate titanate (PZT) films on silicon nitride (SiN) platforms, aiming to enhance performance in integrated photonic circuits. Silicon nitride has emerged as a key player in CMOS-compatible photonics owing to its advantages over silicon-on-insulator (SOI) platforms, such as broader transparency range and lower propagation and nonlinear losses. However, the development of active components like modulators on SiN has been limited due to its insulating and centrosymmetric nature, which poses challenges for traditional modulation techniques used in silicon platforms.

Research Overview

The paper details a novel approach to modulator design by leveraging the Pockels effect in thin-film PZT deposited onto SiN. The authors demonstrate modulators operational across both O- and C-bands, achieving bias-free operation, bandwidths exceeding 33 GHz, and data rates reaching 40 Gbps. Propagation losses as low as 1 dB/cm have been recorded, and the half-wave voltage-length product ($V_\pi L$) is measured at approximately 3.2 Vcm, with simulations suggesting further optimization potential to reduce this value below 2 Vcm.

Strong Numerical Results

The strong numerical results showcased in the paper include bandwidths beyond 33 GHz and data rates of 40 Gbps, alongside low propagation losses ($\alpha \approx 1$ dB/cm). The $V_\pi L$ measurement of 3.2 Vcm suggests an efficient electro-optic response, signifying potential for high-performance modulation on SiN.

Implications

The implications of these findings are extensive, suggesting that SiN platforms could be pivotal in advancing photonics, particularly in fields like quantum optics, microwave photonics, and optical phased arrays. The ability to leverage PZT films on SiN also opens avenues for complex encoding schemes like QPSK, which are challenging with absorption modulation techniques. Practically, these developments could transition integrated photonic circuits towards higher efficiency, scalability, and operational bandwidths.

Future Developments

Future developments may focus on optimizing the waveguide configurations and exploring additional deposition techniques to further reduce propagation losses and enhance electro-optic response. Additionally, the potential scalability of this approach suggests opportunities for broader integration with electronic systems, offering pathways towards hybrid photonic-electronic devices.

In summary, this work represents significant progress in the field of integrated photonics, particularly for SiN-based platforms, offering a promising route to high-performance phase modulation with practical applications across various advanced fields. The insights provided here underscore the potential of SiN as a foundational material for next-generation photonic devices, encouraging further exploration and development within the scientific community.