Silicon photonics is now considered the photonics platform of choice for short-reach data center single mode pluggable transceivers. With the emergence of co-packaged optics concepts, it can also enable high performance computing with power-efficient interconnect, but also Lidar system integration or even optical quantum computing. In this paper we will present an overview of what can be achieved in state-of-the-art silicon photonics platforms and we will discuss some of the emerging technology trends. In particular, we will discuss the integration of LPCVD SiN in an active silicon photonics platform.

Mach-Zehnder interferometers (MZIs) are essential components that are used in a variety of wavelength division multiplexing (WDM) systems. Wavelength-sensitive straight directional couplers (DCs) are usually used as the beam splitter and combiner in traditional waveguide-based MZIs, which often limit the operational bandwidth and cause additional insertion loss. To overcome these challenges, we present an MZI based on bent DCs achieving $2.7\times $ increase in operational wavelength range, expanding the bandwidth from 36.7 nm in straight DC-based MZIs to at least 100 nm, while maintaining a large extinction ratio (ER) $\mathrm {\geq 18.4~dB}$ . The proposed MZI is robust across a 300 mm wafer, achieving minimum ER over 100 nm wavelength range of ${\mathrm {14.3 }}\sim {\mathrm {18.4~dB}}$ in all the 63 measured dies, significantly outperforming MZIs based on straight DCs, which exhibit minimum ER of ${\mathrm {4.2~ }}\sim {\mathrm {6.1~dB}}$ . Finally, the proposed MZI is theoretically proven to be highly efficient for more complex WDM systems. Transfer matrix method calculations for 16 −channel MZI-based WDM system demonstrate an improvement of the worst-channel isolation from 5.42 dB to 17.18 dB and the average insertion loss from 1.02 dB to 0.30 dB, as compared to the straight DC based counterpart. This underscores the potential of the proposed MZI to enable scalable and high-performance WDM systems.

We report the recent progress of waveguide-coupled O-band GeSi quantum confined stark effect electroabsorption modulators, monolithically integrated in a Si photonics platform on 300 mm Silicon-on-insulator wafers with 220 nm thick Si top layer. A wafer-scale analysis of static insertion loss (IL) and extinction ratio (ER) is presented, showing IL down to 7.5 dB with ER of 5 dB for a 36.8 µm long device, at drive voltages of 2 V peak-to-peak. Modulation bandwidths beyond 50 GHz are demonstrated, with an extracted junction capacitance of 57 fF and series resistance of 8.3 Ω. Finally, open eye diagrams are demonstrated for non-return-to-zero on-off keying (NRZ-OOK) modulation for data rates from 40 Gb/s up to 64 Gb/s, with dynamic extinction ratio of 2.5 dB, at 1320 nm wavelength.

We present a collective PIC die-to-wafer dielectric bonding process, enabling SiN waveguide-based die-to-wafer evanescent couplers with insertion losses of 0.36 ±0.18dB at 1310nm wavelengths, paving the way to optically interconnected 300mm wafer-scale multi-chip compute systems.

A color mixing light-emitting diode (LED) light engine that can replace 2-kW halogen–Fresnel spotlight with high-luminous flux in excess of 20,000 lm is reported for applications in professional stage and studio lighting. The light engine focuses and mixes the light from 210 LEDs of five different colors through a microlens array (MA) at the gate of $Ø50mm$. Hence, it produces homogeneous color-mixed tunable white light from 3000 to 6000 K that can be adjustable from flood to spot position providing 10% translational loss, whereas the corresponding loss from the halogen–Fresnel spotlight is 37%. The design, simulation, and optimization of the light engine is described and compared to the experimental characterization of a prototype. The light engine is optimized through the simulated design of reflector, total internal reflection lens, and MA, as well as the number of LEDs. An optical efficiency of 59% and a luminous efficacy of $33lm/W$ are achieved, which is three times higher than the 2-kW halogen–Fresnel spotlight. In addition to having color rendering of color rendering index $Ra>85$ and television lighting consistency index $12>70$, the dimmable and tunable white light can be color controlled during the operational time.

A collective die-to-wafer (CoD2W) assembly process is demonstrated enabling low-loss die-to-wafer evanescent optical coupling, paving the way to future wafer-level optically interconnected multi-XPU compute systems. As a proof-of-concept demonstrator, PIC chiplets and an optical interconnect wafer were co-designed and fabricated, each having embedded SiN waveguides (WG) and evanescent couplers (EVC). Frontside and backside alignment structures were included to enable accurate alignment of the PIC dies to the interconnect wafer. Before assembly, the PIC dies were thinned to 100 μm and subsequently transferred from a temporary carrier to the target interconnect wafer. After the full process, we realized an assembly yield of up to 96% of mostly void-free dies with die-to-target wafer alignment of 2.4 μm (m+3s), resulting in die-to-wafer optical coupling losses below 0.5 dB at 1310 nm for 76% of the dies.