Vertically Integrated Systems (Germany)

Vertical-cavity surface-emitting laser (VCSEL)-based transmission over multimode fiber (MMF) has achieved data rates of 100G per lane and is progressing towards 200G/lane, which demands more modal bandwidth from MMF to ensure adequate transmission reach. We address the needs of higher modal bandwidth from the point of view of engineering VCSEL launch conditions. We explore the options for using subsets of 10 standard-based launch conditions by analyzing the measured encircled fluxes from commercial VCSEL transceivers over two options. By utilizing experimentally measured MMF data, we demonstrated a significant improvement in modal bandwidth with these options. The launch conditions also impact the wavelength dependence of modal bandwidth for VCSELs operating at wavelengths longer than 850 nm. We conducted detailed Monte Carlo simulation of the wavelength dependence of modal bandwidth over MMFs. For one launch condition option using a smaller area, the modal bandwidths are improved over the effective modal bandwidth (EMB), and favor very high data rate transmission by allowing the use of a smaller area photodetector.

In this work we investigate the ultrabroadband dynamics of transverse coupled cavity VCSELs. This study is based on a multimode rate equation model, whose parameters are directly provided by a full-wave vectorial electromagnetic solver. This approach sets a step towards the comprehensive physicsbased modeling of transverse-coupled cavity VCSELs, providing a relation between the features of the optical supermodes and the enhancements of the intensity modulation response. The approach emphasizes how the bandwidth enhancement, ascribable to a photon-photon resonance picture, can be triggered by forcing asymmetries in the bias and modulation contacting scheme of the device, and the importance of collecting the fields from each single cavity, providing an interpretation of recent experimental observations and paving the way towards more systematic design strategies.

In this paper we report high frequency (50 – 100GHz range) optical field intensity oscillations in a laterally-coupled-cavity vertical cavity surface-emitting laser. The oscillating frequency is defined by the photon energy splitting of the coupled states, each oscillating at a frequency defined by the related photon energy. As a result of constructive or destructive interference the optical field intensity reaches maximum either in the left or in the right aperture. As the frequency difference is small as compared to the averaged photon frequency, the cavities are quasi-resonant and the interference effect is strong, causing an intense resonance frequency with integrated intensity of at least 3-fold higher as compared to the resonance oscillation frequency feature. The effect is observed at low and at high current destinies. With proper design of the cavities, one should enable a simple and reliable solution for high-speed data transmission at data rates ~200 Gb/s and beyond. The effect coexists with spin-related frequency resonances allowing its combination with novel concepts in data transmission.

This paper demonstrates why VCSEL-based transmitter systems are not able to capitalize on higher-order PAM modulation formats (such as PAM-4) to push the link data rate towards 100 Gbit/s with BER of better than 10−5. First, the non-linear and biasing-dependent VCSEL behavior is analyzed in great detail to prove why state-of-the-art VCSELs with linear equalization are not able to reach these bandwidth targets. Consequently, based on an enhanced VCSEL model, a digital non-linear transmit equalizer is proposed to overcome voltage-dependent relaxation frequency shifts as well as data-dependent VCSEL bandwidth variations. The proposed digital non-linear equalizer is compared with a standard linear FFE structure using PAM-4 transmission experiments of 100 Gbit/s and beyond. This way, the proposed non-linear equalizer reveals a BER improvement of more than 30-fold compared to a linear FFE at a data rate of 80 Gbit/s. Finally, at 112 Gbit/s PAM-4 the non-linear equalizer was successfully demonstrated at a BER of 1.5·10−7.

We present the first true voltage-mode VCSEL driver achieving 60 Gbit/s at peak efficiency of 0.36pJ/bit with BER < 1e-12 improving the state-of-the-art by a factor of 2. Transmission experiments showcase error-free 56 Gbit/s transmission up to 100 m fiber. Advanced demonstration enables even 224 Gbit/s when using SWDM at a total efficiency of 0.4 pJ/bit.

The paper presents multi-aperture single mode 850nm VCSEL with optical modulation bandwidth exceeding 30GHz and narrow optical spectrum width enabling long distance highspeed data transmission exceeding 800m over OM4 multi-mode fiber.

We demonstrate parallel high speed data transmission over single multimode fiber using VCSELs operating in the SWDM wavelength range (850 nm – 940 nm). Total demonstrated throughput of such system reaches 500 Gbit/s with 4-PAM modulation and 600 Gbit/s with DMT modulation.

Electrically-pumped optical microcavity single photon sources based on single quantum dots are investigated by numerical modelling techniques. Design of electrically driven 1.3 μm-range single photon source with intra-cavity contacts and multiply oxide aperture layers is proposed. About two times improvement in photon coupling efficiency into the single-mode fiber is demonstrated as compared with single photon source based on cylindrical micropillar.

Recent advances in VCSELs and VCSEL-based links are reviewed. The impact of the VCSEL bandwidth extension from 22 GHz to 28 GHz on the performance of energy-efficient link capable of operating above 71 Gbit/s in NRZ modulation is studied.

International audience