Worldwide demand for digital interconnections is driven both by increasing data exchanges and by an increasing number of human and non-human users. Optical communications are commonly used to answer this demand, exploiting the network of optical fibers deployed to interconnect data centers and users alike. The data streams across this planet-scale infrastructure are routed at high-speed by multiple electronic-photonic transducer nodes, located everywhere from inside data centers to inside users’ homes (FTTH). Each node in turn requires multiple high performance optical transceivers, to transmit and receive the information along the network.
Photonic Integrated Circuits (PIC) have been a promising technology for low-power & high-performance optical functions in low-volume systems.The availability of relatively low-cost optical telecommunication devices, such as telecom lasers and optical modulators, has gained the interest of other fields of science and technology, working with infrared light. Photonic circuits can be tuned to function at wavelengths centered on spectral absorption rays of gases of interest (H2O, CO, CO2), for sensing purposes.

III-V Lab and CEA-LETI recently demonstrated selective area growth (SAG) of III-V materials on Silicon, a key process enabling the fabrication of different frequency-tailored quantum wells simultaneously. However, to address future needs, the performances of actual III-V on Silicon modulators need to be improved.
This thesis aims at the development of advanced modulators, in order to demonstrate state of the art transceivers, which could be implemented in the future using the previously developed SAG technology.
Such devices based on III-V waveguides on silicon will be modelled, designed, fabricated and tested towards high-speed light phase and intensity modulation.
This work will require opto-electronic optimizations of the InP-based III-V stack and coupling to the SOI waveguides in order to reach low losses, low absorption, and a higher phaseshift per volt, for high bandwidth capabilities reaching 100 GHz.
High-speed phase modulators will be demonstrated in coherent communication systems, targeting beyond 16QAM modulation schemes for 400 Gbps/lane.
High-precision frequency modulation will be demonstrated in single-sideband modulation (oSSBM), for 100 GHz frequency shifting in sensing applications.

The PhD will be based at CEA-LETI (Grenoble), within the Silicon Photonics Integration Laboratory, in the framework of the R&D Photonics Program existing between CEA and III-V Lab that will co-supervise the thesis work.