Charles Baudot

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.

Silicon Photonics R&D and Manufacturing on 300-mm Wafer Platform

Industrial implementation of a silicon photonics platform using 300-mm SOI wafers and aiming at 100 Gb/s aggregate data-rate application is demonstrated. The integration strategy of electronic and photonic ICs, 300-mm process flow, and process variability are discussed, and performances of the passive and active optical devices are shown. An example of a low-cost LGA-based package together with a fiber assembly is given. RX and TX circuits operating at 25 Gb/s are demonstrated. Finally, the process evolution toward the integration of the backside reflector and multiple silicon etching level is demonstrated.

A 40 Gbit/s optical link on a 300-mm silicon platform

We demonstrated 40 Gbit/s optical link by coupling a silicon (Si) optical modulator to a germanium (Ge) photo-detector from two separate photonic chips. The optical modulator was based on carrier depletion in a pn diode integrated in a 950-µm long Mach-Zehnder interferometer. The Ge photo-detector was a lateral pin diode butt coupled to a silicon waveguide. The overall loss, which is mainly due to coupling (3 grating couplers times ~4 dB) was estimated to be lower than 18 dB. That also included modulator loss (4.9-dB) and propagation loss (<1 dB/cm). Both optoelectronic devices have been fabricated on a 300-mm CMOS platform to address high volume production markets.

Recent progress in Silicon Photonics R&D and manufacturing on 300mm wafer platform

A low cost 28Gbits/s Silicon Photonics platform using 300mm SOI wafers is demonstrated. Process, 3D integration of Electronic and Photonic ICs, device performance, circuit results and low cost packaging are discussed.

40Gbit/s germanium waveguide photodetector on silicon

We report a Germanium lateral pin photodiode integrated with selective epitaxy at the end of silicon waveguide. A very high optical bandwidth estimated at 120GHz is shown, with internal responsivity as high as 0.8A/W at 1550nm wavelength. Open eye diagram at 40Gb/s was obtained under zero-bias at wavelength of 1.55μm.

Applications of multi-walled carbon nanotube in electronic packaging

Thermal management of integrated circuit chip is an increasing important challenge faced today. Heat dissipation of the chip is generally achieved through the die attach material and solders. With the temperature gradients in these materials, high thermo-mechanical stress will be developed in them, and thus they must also be mechanically strong so as to provide a good mechanical support to the chip. The use of multi-walled carbon nanotube to enhance the thermal conductivity, and the mechanical strength of die attach epoxy and Pb-free solder is demonstrated in this work.

Schottky electroluminescent diodes with n-doped germanium

n-doped germanium can be used as an active material for the realization of an optical source under electrical pumping. We propose to use Schottky contacts for germanium electroluminescent devices, and we show that carrier injection and electroluminescence in these Schottky devices can be optimized by depositing a thin Al2O3 interfacial layer on top of n-doped germanium. In the latter case, hole injection is optimized due to the drastic decrease of interface trap densities and room-temperature electroluminescence can be observed at small current injection with a higher differential efficiency as compared to the standard Schottky sample.

Solubility, dispersion and bonding of functionalised carbon nanotubes in epoxy resins

Carbon nanotubes as fillers in an epoxy matrix for mechanical reinforcement and heat diffusion enhancement are tested. We demonstrate a method to covalently graft functional molecules on carbon nanotubes to alter the filler/matrix interface incompatibilities, making the carbon nanotubes become soluble in epoxies and allows better homogenisation of the fillers in the matrix. As a result, the carbon nanotubes will bond to the epoxy matrix during polymerisation, and thus create a better mechanical strength and heat transfer enhancement.

Design of Low-Loss Polarization Splitting Grating Couplers

We report polarization splitting grating couplers on double-SOI substrates with loss below 2 dB, optimized polarization dependence and excellent manufacturability. We illustrate the optimization of the scatterers with electromagnetic simulations.

Low voltage 25Gbps silicon Mach-Zehnder modulator in the O-band

In this work, a 25 Gb ps silicon push-pull Mach-Zehnder modulator operating in the O-Band (1260 nm - 1360 nm) of optical communications and fabricated on a 300 mm platform is presented. The measured modulation efficiency (VπLπ) was comprised between 0.95 V cm and 1.15 V cm, which is comparable to the state-of-the-art modulators in the C-Band, that enabled its use with a driving voltage of 3.3 Vpp, compatible with BiCMOS technology. An extinction ratio of 5 dB and an on-chip insertion losses of 3.6 dB were then demonstrated at 25 Gb ps.