Heterogeneous integration of III-V materials onto silicon photonics has experienced enormous progress in the last few years, setting the groundwork for the implementation of complex on-chip optical systems that go beyond single device performance. Recent advances on the field are expected to impact on next generation optical communications to attain low power, high efficiency and portable solutions. To accomplish that aim, intense research on hybrid lasers, modulators and photodetectors is being done to implement optical modules and photonic integrated networks with specifications that match the market demands. Similarly, important advances on packaging and thermal management of hybrid photonic integrated circuits (PICs) is currently in progress. In this paper, we report our latest results on hybrid III-V on Si transmitters, receivers and packaged optical modules for high-speed optical communications. In addition, a review of recent advances in this field will be provided for benchmarking purposes.

Silicon photonics is one of the most prominent technology platforms for integrated photonics and can support a wide variety of applications. As we move towards a mature industrial core technology, we present the integration of silicon nitride (SiN) material to extend the capabilities of our silicon photonics platform. Depending on the application being targeted, we have developed several integration strategies for the incorporation of SiN. We present these processes, as well as key components for dedicated applications. In particular, we present the use of SiN for athermal multiplexing in optical transceivers for datacom applications, the nonlinear generation of frequency combs in SiN micro-resonators for ultra-high data rate transmission, spectroscopy or metrology applications and the use of SiN to realize optical phased arrays in the 800–1000 nm wavelength range for Light Detection And Ranging (LIDAR) applications. These functionalities are demonstrated using a 200 mm complementary metal-oxide-semiconductor (CMOS)-compatible pilot line, showing the versatility and scalability of the Si-SiN platform.

In this paper we present the hybrid III-V/Si photonic platform developed in CEA-LETI. The overall integration is done in a fully CMOS compatible 200mm technology, scalable to 300mm wafers, leveraging the large scale integration capabilities of silicon photonics. III-V material is integrated on top of a mature silicon photonic front-end wafer through direct molecular bonding enabling the monolithic integration of light sources. DFB and DBR laser reference designs are used as test vehicules for the process validation. A modular approach is used in order to minimize the impact on the already qualified silicon-based devices. Collective III-V die bonding is proposed in this platform. CMOS compatible metallizations are used to form ohmic contact on n-InP and P-InGaAs leading to contact resistivity in the range of $10^{-6}\Omega$ .cm2. A planarized 2-metal level BEOL is used to connect the device, leading to a drastic reduction of series resistance. Finally, the funcitonnality of both types of lasers is demonstrated with SMSR up to 50dB and maximum output power of 5mW.

Recent advances on hybrid III–V/Si lasers and semiconductor optical amplifiers using wafer bonding are reported. Hybrid optical amplifiers exhibit 28 dB internal gain, 9 dBm saturation power in the output silicon waveguide, and 10–11 dB of internal noise factor. Moreover, using optical amplifiers as optical gates, we demonstrate a successful switching operation of optical packet/burst without penalties compared to classical optical amplifiers. The hybrid silicon lasers allow single mode operation and wavelength tunability over 30 nm by exploiting silicon ring resonators thermo-optical effect. Moreover transmission over 60 km single-mode fiber at 10 Gb/s from a directly modulated III–V on Silicon hybrid laser is also demonstrated. Finally, we achieved 21.4 Gb/s modulation over 12 wavelengths using a high-speed directly modulated silicon hybrid laser with improved E/O bandwidth.

Optical modulators are key components to realize photonic circuits, and Mach-Zehnder modulators (MZM) are often used for high speed short reach interconnects. In order to maximize the tolerable path loss of a transmission link at a given bitrate, the MZM needs to be optimized. However, the optimization can be complex since the overall link performance depends on various parameters, and, for the MZM in particular, implies several trade-offs between efficiency, losses, and bandwidth. In this work, we propose a general and rigorous method to optimize silicon MZM. We first describe the optical link, and the numerical method used for this study. Then we present the results associated to the active region for 1310 nm applications. An analytical model is generated, and allows us to quickly optimize the p-n junction depending of the targeted performances for the MZM. Taking into account the required optical link parameters, the maximum tolerable path losses for different length of MZM is determined. By applying this method, simulations show that the optimum MZM length for 25 Gbps applications is 4 mm with an efficiency of 1.87 V·cm, 0.52 dB/mm of losses. A tolerable path loss of more than 25 dB is obtained.

We report on a fully integrated hybrid III-V on silicon distributed feedback (DFB) laser integrated with a ring resonator. We demonstrate an enhanced extinction ratio up to 5 dB at 25 Gb/s of the distributed feedback laser when the ring-resonator is finely tuned. We validated the transmitter with a 20 km transmission with only 2.5 dB penalty and 20 dB power budget.