David Bouville

40 Gbit/s low-loss silicon optical modulator based on a pipin diode

40 Gbit/s low-loss silicon optical modulators are demonstrated. The devices are based on the carrier depletion effect in a pipin diode to generate a good compromise between high efficiency, speed and low optical loss. The diode is embedded in a Mach-Zehnder interferometer, and a self-aligned fabrication process was used to obtain precise localization of the active p-doped region in the middle of the waveguide. Using a 4.7 mm (resp. 0.95 mm) long phase shifter, the modulator exhibits an extinction ratio of 6.6 dB (resp. 3.2 dB), simultaneously with an optical loss of 6 dB (resp. 4.5 dB) at the same operating point.

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.

High extinction ratio 10 Gbit/s silicon optical modulator

High speed and high extinction ratio silicon optical modulator using carrier depletion is experimentally demonstrated. The phase-shifter is a 1.8 mm-long PIPIN diode which is integrated in a Mach Zehnder interferometer. 8.1 dB Extinction Ratio at 10 Gbit/s is obtained simultaneously with optical loss as low as 6 dB.

Sharp bends and Mach-Zehnder interferometer based on Ge-rich-SiGe waveguides on SiGe graded buffer.

The integration of germanium (Ge)-rich active devices in photonic integrated circuits is challenging due to the lattice mismatch between silicon (Si) and Ge. A new Ge-rich silicon-germanium (SiGe) waveguide on graded buffer was investigated as a platform for integrated photonic circuits. At a wavelength of 1550 nm, low loss bends with radii as low as 12 µm and Multimode Interferometer beam splitter based on Ge-rich SiGe waveguide on graded buffer were designed, fabricated and characterized. A Mach Zehnder interferometer exhibiting a contrast of more than 10 dB has been demonstrated.

Strong quantum-confined Stark effect from light hole related direct-gap transitions in Ge quantum wells

A strong quantum-confined Stark effect (QCSE) from light hole related transitions at the Γ point (LH1-cΓ1) in Ge/Si0.15 Ge 0.85 multiple quantum wells is demonstrated from both photocurrent and optical transmission measurements. Our experimental results show a large and sharp optical absorption peak due to LH1-cΓ1 transitions, and its associated strong absorption change based on the QCSE. By exploiting LH1-cΓ1 transitions, optical modulators with improved compactness and competitive extinction ratio and optical loss can be envisioned for low energy chip-scale optical interconnect applications.

Ge quantum-well waveguide modulator at 1.3μm

We report on the developments of Ge/SiGe quantum well (QW) waveguide modulators operating at 1.3 μm. First we studied QW structures grown on a 13-μm SiGe buffer on bulk silicon. Light was directly coupled and propagated in the active region. Using a 3-μm wide and 50-μm long modulator, an extinction ratio larger than 4 dB was obtained for a drive voltage lower than 5 V in a 15 nm wavelength range. Then simulations were performed to evaluate the performances of an integrated modulator on silicon on insulator (SOI) platform. An eigenmode expension method was used to model the vertical optical coupling between SOI waveguide and Ge/SiGe devices. It is shown that a reduction of the thickness of the buffer leads to a significant improvement in the performances (extinction ratio, insertion loss) and footprint of the waveguide-integrated devices.

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.

High speed silicon modulators and germanium detectors

40Gbit/s optical modulators based on carrier depletion effect and germanium photodetectors integrated in silicon waveguides have been demonstrated at a wavelength of 1.55μm.