arXiv subjects

Geert Van Steenberge

Publications and source records attributed to Geert Van Steenberge.

4 recordsLinked to original sources

arXiv2026

Polarization Dynamics in VCSELs Under Sinusoidal Signal Modulation around the Polarization Switching point

Vertical-Cavity Surface-Emitting Lasers (VCSELs) combine compact geometry, low threshold current, and ease of integration, making them central to modern photonic systems. However, their polarization behavior remains a critical factor affecting performance, as the emission state can switch between orthogonally polarized modes around the so-called polarization switching point. This regime exhibits high sensitivity, where small perturbations induce abrupt polarization changes and nonlinear responses. In this work, the polarization dynamics of VCSELs under sinusoidal current modulation around the switching point are numerically investigated using the Spin-Flip Model. The study examines the influence of modulation frequency, amplitude, and bias current, revealing distinct dynamical regimes including polarization locking, periodic and irregular switching. The observed transitions between regimes elucidate the interplay between modulation and polarization stability, providing insight into the control of VCSEL dynamics for high-speed optical communication and sensing applications.

physics.optics↗

arXiv2025

A 3D-integrated BiCMOS-silicon photonics high-speed receiver realized using micro-transfer printing

Meeting the escalating demands of data transmission and computing, driven by artificial intelligence (AI), requires not only faster optical transceivers but also advanced integration technologies that can seamlessly combine photonic and electronic components. Traditional approaches struggle to overcome the parasitic limitations arising from fabricating those components using different processes. Here, we report a novel 3D heterogeneously integrated optical receiver based on micro-transfer printing (μTP), enabling the co-integration of a compact bipolar CMOS (BiCMOS) electronic chiplet (0.06 mm2) directly onto a silicon photonic integrated circuit (SiPIC). While previous μTP demonstrations have focused primarily on photonic integration, our work pioneers the direct integration of electronics and photonics, significantly enhancing performance and scalability. The resulting optical receiver achieves 224 Gb/s four-level pulse amplitude modulation (PAM-4) operation, delivering -5.2 dBm optical modulation amplitude(OMA) sensitivity at a bit-error rate (BER) of 2.4 x 10-4, a record-small footprint, and an excellent power efficiency of 0.51 pJ/b. This demonstration not only showcases the potential of μTP for high-density, cost-efficient integration but also represents a critical step toward next-generation optical interconnects in the AI era.

physics.optics↗

arXiv2025

Low-Loss Integration of High-Density Polymer Waveguides with Silicon Photonics for Co-Packaged Optics

Co-Packaged Optics applications require scalable and high-yield optical interfacing solutions to silicon photonic chiplets, offering low-loss, broadband, and polarization-independent optical coupling while maintaining compatibility with widely used approaches for electrical redistribution. We present two heterogeneous integration techniques that enable high-density electrical and optical I/O connections, utilizing adiabatic coupling between on-chip silicon nitride (SiN) waveguides and package-level polymer optical waveguides. In the first approach, polymer waveguides are patterned using standard lithography directly on the surface of the photonic chip, ensuring compatibility with chip embedding as commonly employed in chip-first fanout wafer-level packaging. In the second approach, photonic chips are flip-chip bonded to the package substrate. Both techniques have been experimentally validated, achieving a coupling efficiency near 1 dB between SiN and polymer waveguides in O-band, for both TE and TM polarizations. SiN tapers were designed using the "Mono" method to optimize phase-matching conditions between the two waveguides, a critical requirement for integrating diverse optical components. These results demonstrate the potential of polymer waveguides in Co-Packaged Optics applications, achieving sub-2 dB chip-to-chip and chip-to-fiber coupling losses.

physics.optics↗

arXiv2024

Wavelength tuning of VCSELs via controlled strain

Besides major advantages for telecommunication applications, VCSELs have attracted interest for their potential for neuro-inspired computing, frequency comb generation or high-frequency spin oscillations. In the meantime, strain applied to the laser structure has been shown to have a significant impact on the laser emission properties such as the polarization dynamics or birefringence. In this work, we further explore the influence of strain on VCSELs and how this effect could be used to fine tune the laser wavelength. Through a comprehensive investigation, we demonstrate consistent wavelength shift up to 1 nm and report a sensitivity between 0.12 to 0.18 nm / millistrain. We also record birefringence values up to 292 GHz. Our results show that controlled strain level could be considered for fine wavelength tuning and possibly alleviate the selection of VCSEL for precise wavelength requirements.

physics.optics↗