Aurélie Souhaité

Low loss 40 Gbit/s silicon modulator based on interleaved junctions and fabricated on 300 mm SOI wafers

We demonstrate high-speed silicon modulators based on carrier depletion in interleaved pn junctions fabricated on 300 mm-SOI wafers using CMOS foundry facilities. 950 µm-long Mach Zehnder (MZ) and ring resonator (RR) modulator with a 100 µm radius, were designed, fabricated and characterized. 40 Gbit/s data transmission has been demonstrated for both devices. The MZ modulator exhibited a high extinction ratio of 7.9 dB with only 4 dB on-chip losses at the operating point.

DAPHNE silicon photonics technological platform for research and development on WDM applications

A new technological platform aimed at making prototypes and feasibility studies has been setup at STMicroelectronics using 300mm wafer foundry facilities. The technology, called DAPHNE (Datacom Advanced PHotonic Nanoscale Environment), is devoted at developing and evaluating new devices and sub-systems in particular for wavelength division multiplexing (WDM) applications and ring resonator based applications. Developed in the course of PLAT4MFP7 European project, DAPHNE is a flexible platform that fits perfectly R&D needs. The fabrication flow enables the processing of photonic integrated circuits using a silicon-on-insulator (SOI) of 300nm, partial etches of 150nm and 50nm and a total silicon etching. Consequently, two varieties of rib waveguides and one strip waveguide can be fabricated simultaneously with auto-alignment properties. The process variability on the 150nm partially etched silicon and the thin 50nm slab region are both less than 6 nm. Using a variety of different implantation configurations and a back-end of line of 5 metal layers, active devices are fabricated both in germanium and silicon. An available far back-end of line process consists of making 20 μm diameter copper posts on top of the electrical pads so that an electronic integrated circuit can be bonded on top the photonic die by 3D integration. Besides having those fabrication process options, DAPHNE is equipped with a library of standard cells for optical routing and multiplexing. Moreover, typical Mach-Zehnder modulators based on silicon pn junctions are also available for optical signal modulation. To achieve signal detection, germanium photodetectors also exist as standard cells. The measured single-mode propagation losses are 3.5 dB/cm for strip, 3.7 dB/cm for deep-rib (50nm slab) and 1.4 dB/cm for standard rib (150nm slab) waveguides. Transition tapers between different waveguide structures are as low as 0.006 dB.

Design of integrated capacitive modulators for 56Gbps operation

We present TCAD simulation results for the integration of capacitive modulators in a 300mm SOI platform. We show that tuning the capacitor oxide thickness improves the bandwidth and the component efficiency, leading to 860μm active length, 56Gbps data rate and low power consumption (1.2Vpp).

Impact of process variability of active ring resonators in a 300mm silicon photonic platform

We study the process variability impact of silicon ring modulators on resonance wavelength, which is a key parameter to design WDM communication systems based on those devices.

Progresses in 300mm DUV photolithography for the development of advanced silicon photonic devices

In this paper we report on advances in DUV dry photolithography both for etching and implantation of silicon photonic devices. We explain why silicon patterning is a critical building block in silicon photonics and what are the challenges related to that process. Furthermore, it also occurs that some silicon photonic devices need implantation lithographic conditions which are also specific to the technology. For that purpose, we developed a dedicated DUV 193nm implantation lithography to address that need.

40 Gbit/s silicon modulators fabricated on 200-mm and 300-mm SOI wafers

We present 40 Gbit/s optical modulators based on different types of phase shifters (lateral pn, pipin, and interleaved pn junction phase). Those structures were processed both on 200 and 300mm SOI wafers, available in large-scale microelectronic foundries. Both Ring Resonators (RR) and Mach Zehnder (MZ) modulators were fabricated. As an example, MZ modulator based on 0.95 mm long interleaved pn junction phase shifter delivered a high ER of 7.8 dB at 40 Gbit/s with low optical loss of only 4 dB. Ring modulator was also fabricated and characterized at high-speed, exhibiting 40 Gbit/s.

Introducing photonic devices for 40Gbits/s wavelength division multiplexing transceivers on 300-mm SOI wafers using CMOS processes

We demonstrate the feasibility of producing advanced silicon photonic devices for future data communication nodes at 40Gbps using CMOS compatible processes in a 300mm wafer fab. Basic building blocks are shown together with various wavelength division multiplexing solutions. All the devices presented are integrated on 220nm SOI or locally grown epitaxial germanium.