A. Brimont

High-speed modulation of a compact silicon ring resonator based on a reverse-biased pn diode

We demonstrate high speed modulation based on a compact silicon ring resonator operating in depletion mode. Our device features an electrical small signal bandwidth of approximately 19 GHz, which is the fastest silicon ring resonator modulator reported to date.

Highly efficient crossing structure for silicon-on-insulator waveguides

A compact waveguide crossing structure with low transmission losses and negligible crosstalk is demonstrated for silicon-on-insulator circuits. The crossing structure is based on a mode expander optimized by means of a genetic algorithm leading to transmission losses lower than 0.2 dB and crosstalk and reflection losses below 40 dB in a broad bandwidth of 20 nm. Furthermore, the resulting crossing structure has a footprint of only 6x6 microm(2) and does not require any additional fabrication steps.

High speed silicon electro-optical modulators enhanced via slow light propagation

While current optical communication networks efficiently carry and process huge amounts of digital information over large and medium distances, silicon photonics technology has the capacity to meet the ceaselessly increasing demand for bandwidth via energy efficient, inexpensive and mass producible short range optical interconnects. In this context, handling electrical-to-optical data conversion through compact and high speed electro-optical modulators is of paramount importance. To tackle these challenges, we combine the attractive properties of slow light propagation in a nanostructured periodic waveguide together with a high speed semiconductor pn diode, and demonstrate a highly efficient and mass manufacturable 500 µm-long silicon electro-optical device, exhibiting error free modulation up to 20 Gbit/s. These results, supported by modulation rate capabilities reaching 40 Gbit/s, pave a foreseeable way towards dense, low power and ultra fast integrated networks-on-chip for future chip-scale high performance computing systems.

Ring-Assisted Mach–Zehnder Interferometer Silicon Modulator for Enhanced Performance

A high-speed ring-assisted Mach-Zehnder interferometer (RAMZI) silicon modulator is reported and experimentally demonstrated. The RAMZI optical structure relaxes the optimum coupling condition of the ring without degrading the modulator performance, which therefore improves the modulator robustness against fabrication deviations and could eventually lead to an enhanced modulation bandwidth. Hence, our RAMZI silicon modulator, based on carrier depletion in a pipin active structure, exhibits a 3 dB electro-optical bandwidth of 19 GHz, enabling up to 20 Gbit/s data transmission over a RF/optical interaction length of only ~200 μm.

CMOS Compatible Silicon-on-Insulator Polarization Rotator Based on Symmetry Breaking of the Waveguide Cross Section

A polarization rotator in silicon-on-insulator technology based on breaking the symmetry of the waveguide cross section is reported. The 25- μm-long device is designed to be integrated with standard grating couplers without the need for extra fabrication steps. Hence, fabrication is carried out by a 2-etch-step complementary metal-oxide-semiconductor compatible process using 193-nm deep ultraviolet lithography. A polarization conversion efficiency of more than -0.85 & dB with insertion losses ranging from -1 to -2.5 & dB over a wavelength range of 30 nm is demonstrated.

Group-index engineering in silicon corrugated waveguides.

We present experimental measurements of the group index in tailored silicon corrugated waveguides. Nearly constant group index as high as ng=14 ±0.5 in a 13 nm range was measured in a 50 µm long waveguide.

High-contrast 40 Gb/s operation of a 500 μm long silicon carrier-depletion slow wave modulator

In this Letter, we demonstrate a highly efficient, compact, high-contrast and low-loss silicon slow wave modulator based on a traveling-wave Mach-Zehnder interferometer with two 500 μm long slow wave phase shifters. 40  Gb/s operation with 6.6 dB extinction ratio at quadrature and with an on-chip insertion loss of only 6 dB is shown. These results confirm the benefits of slow light as a means to enhance the performance of silicon modulators based on the plasma dispersion effect.

Slow-Light-Enhanced Silicon Optical Modulators Under Low-Drive-Voltage Operation

The integration of nanophotonics components with advanced complementary metal-oxide-semiconductor (CMOS) electronics requires drive voltages as low as 1 V for enabling next-generation CMOS electrophotonics transceivers. Slow-light propagation has been recently demonstrated as an effective mechanism to enhance the modulation efficiency in free-carrier-based electrooptical silicon modulators. Here, we exploit the use of slow light to reduce the driving voltage of carrier-depletion-based Mach-Zehnder modulators. The slow-light phase shifter consists of a p-n junction positioned in the middle of a corrugated waveguide. A modulation efficiency as high as VπLπ ~ 0.6 V·cm is achieved, thus allowing data transmission rates up to 10 Gb/s with a 1.5-Vpp drive voltage and an insertion loss of ~12 dB. The influence of the drive voltage on the modulation speed as well as the variation of the insertion losses with a group index is also analyzed and discussed.

High linear ring-assisted MZI electro-optic silicon modulators suitable for radio-over-fiber applications

The linearity properties of ring-assisted MZI (RAMZI) electro-optic silicon modulators are investigated. When quadrature biased the RAMZI silicon modulator with Vbias,DC=1 V and applied a 1 GHz RF tone frequency, it is obtained a Spurious-Free Dynamic Range (SFDR) of 71.65 dB·Hz2/3, and an input intercept point IIP3=67 dBm. Measurements on QPSK and 16-QAM electrical modulated signals on a 1 GHz carrier also show an experimental error vector magnitude (EVM) lower than 10% and 14% for 20 Msymbol/s and 50 Msymbol/s modulation rates respectively, which corroborates their potential for RoF applications.

Increased sensitivity through maximizing the extinction ratio of SOI delay-interferometer receiver for 10G DPSK

We present an optimized design for a 10G- differential-phase-shift-keyed (DPSK) receiver based on a silicon-on-insulator (SOI) unbalanced tunable Mach-Zehnder interferometer (MZI) switch in sequence with a Mach-Zehnder delay interferometer (MZDI). The proposed design eliminates the limitation in sensitivity of the device produced by the waveguide propagation losses in the delay line. A 2.3 dB increase in receiver sensitivity at a bit-error-rate (BER) of 10(-9) is experimentally measured over a standard implementation. The enhanced sensitivity is achieved with zero power consumption by tuning the operating wavelength or with less than 5 mW for a fixed wavelength using microheaters. Also the foot-print of the device is minimized to 0.11 mm(2) by the use of compact spirals.