Shengbo Xu

Demonstration of wavelength conversion at 40 Gb/s data rate in silicon waveguides

We report an efficient wavelength conversion via four-wave-mixing in reverse biased silicon-on-isolator p-i-n rib waveguides and demonstrate, for the first time, the conversion of a high-speed optical pseudo-random bit sequence data at 40 Gb/s. Results give a wavelength conversion efficiency of -8.6dB using a 8cm long waveguide with clear open eye on the wavelength converted signal . Conversion efficiency as functions of pump power and bias voltages has also been investigated. We show a slope efficiency close to 2 as predicted by theory.

Monolithic integrated Raman silicon laser

We present a monolithic integrated Raman silicon laser based on silicon-on-insulator (SOI) rib waveguide race-track ring resonator with an integrated p-i-n diode structure. Under reverse biasing, we achieved stable, single mode, continuous-wave (CW) lasing with output power exceeding 30mW and 10% slope efficiency. The laser emission has high spectral purity with a measured side mode suppression exceeding 70dB and laser linewidth of <100 kHz. This laser architecture allows for on-chip integration with other silicon photonics components to provide a highly integrated and scaleable monolithic device.

Multichannel dispersion compensation using a silicon waveguide-based optical phase conjugator.

We experimentally demonstrate dispersion compensation using a silicon-based optical phase conjugator. We achieve simultaneous transmission of four dense wavelength division multiplexing (DWDM) channels spaced at 100 GHz and operating at 10 Gbits/s over 320 km of standard fiber. The measured power penalty at bit error rate of 10(-9) is less than 0.3 dB.

Raman amplification of 40 Gb/s data in low-loss silicon waveguides

We demonstrate on-chip Raman amplification of an optical data signal at 40 Gb/s in a silicon-on-insulator p-i-n rib waveguide. Using 230 mW of coupled pump power, on/off gain of up to 2.3 dB is observed, while signal integrity is maintained. In addition, the gain is measured as a function of signal wavelength detuning from the Stokes wavelength. The Lorentzian linewidth of the Raman gain profile is determined to be approximately 80 GHz. This provides applicability for the selective amplification of individual DWDM optical channels.

Integrated silicon photonics for optical networks [Invited]

Feature Issue on Nanoscale Integrated Photonics for Optical Networks Fiber optic communication is well established today in long-haul, metro, and some data communication segments. Optical technologies continue to penetrate more into the network owing to the increase in bandwidth demands; however, they still suffer from too expensive solutions. Silicon photonics is a new technology developing integrated photonic devices and circuits based on the unique silicon material that has already revolutionized the face of our planet through the microelectronics industry. This paper reviews silicon photonics technology at Intel, showing how using the same mature, low-cost silicon CMOS technology we develop many of the building blocks required in current and future optical networks. After introducing the silicon photonics motivation for networks, we discuss the various devices--waveguides, modulators, Raman amplifiers and lasers, photodetectors, optical interconnects, and photonic crystals--from the points of view of applications, principle of operation, process development, and performance results.

Tunable ring resonators for silicon Raman laser and amplifier applications

Recently, low threshold Raman silicon lasers based on ring resonator architecture have been demonstrated. One of the key elements of the laser cavity is the directional coupler that couples both pump and signal light in and out of the ring resonator from the bus waveguide. The coupling coefficients are crucial for achieving desired laser performance. In this paper, we report design, fabrication, and characterization of tunable silicon ring resonators for Raman laser and amplifier applications. By employing a tunable coupler, the coupling coefficients for both pump and signal wavelength can be tailored to their optimal values after the fabrication, which significantly increases the processing tolerance and improves the device performance.

Monolithic integrated ring resonator Raman silicon laser and amplifier

We present a chip-scale ring resonator Raman silicon laser and amplifier based on a silicon-on-insulator rib waveguide with an integrated p-i-n diode structure. The laser cavity consists of a race-track shaped ring resonator connected to a straight bus waveguide via a directional coupler which couples both pump and signal laser light into and out of the cavity. The optical propagation loss of the ring resonator is reduced to <0.3 dB/cm on average and the effective free carrier lifetime in the waveguide can be shortened to <1 ns under reverse biasing, which efficiently reduces the nonlinear loss due to two-photon absorption induced free carrier absorption. We achieve continuous-wave, single-mode lasing with threshold of <20 mW and slope efficiency of >23%. Based on the same ring resonator architecture, we build a compact, chip-scale Raman amplifier that takes advantage of the cavity enhancement effect to lower the pump power and reduce the device size. We achieve over 3 dB amplification with 3 times less pump power in a 3 cm ring resonator compared to a straight waveguide of the same length. Our experimental results agree with simulations. The ring resonator based laser and amplifier can be integrated on chip with other silicon photonics components to provide a monolithic integrated photonic device.

Recent development on silicon-based Raman lasers and amplifiers

We present a monolithic integrated Raman silicon laser and amplifier based on silicon-on-insulator rib waveguide race-track ring resonator with an integrated p-i-n diode structure. Under reverse biasing, we efficiently reduced the nonlinear loss due to two-photon absorption induced free carrier absorption and achieved continuous-wave net gain and stable, single-mode lasing with output power exceeding 30mW and 10% slope efficiency. The laser emission has high spectral purity with a side mode suppression exceeding 70dB and a laser linewidth of <100 kHz. This ring resonator architecture allows for on-chip integration with other silicon photonics components to provide a highly integrated and scaleable monolithic device. Using the ring resonator architecture, we can build a compact, chip scale Raman amplifier that takes advantage of the resonance effect to increase the effective pump power and reduce the device size. Our simulations suggest that a 3dB net gain can be achieved with 4dB less pump power in a 3cm ring compared to a straight waveguide of the same length.

Silicon based chip-scale nonlinear optical devices: Laser, amplifier, and wavelength converter

Taking advantage of the high optical nonlinearity and strong light confinement in silicon waveguides, chip-scale nonlinear devices such as Raman lasers, amplifiers, and wavelength converters are realized. Performance and application potential of these devices are presented.

Recent Development on Silicon Raman Lasers and Amplifiers

Silicon photonics has made rapid progress in recent years achieving several key breakthroughs. Chip-scale silicon lasers and amplifiers based on stimulated Raman scattering have been successfully demonstrated. Recent development of Raman silicon lasers and amplifiers based on ring resonator architecture enables dimension scalability and monolithic integration with other photonics components