Amy C. Turner-Foster

Bio: Amy C. Turner-Foster is an academic researcher from Cornell University. The author has contributed to research in topics: Silicon photonics & Silicon. The author has an hindex of 17, co-authored 47 publications receiving 2621 citations. Previous affiliations of Amy C. Turner-Foster include University College London & Columbia University.

CMOS-compatible multiple-wavelength oscillator for on-chip optical interconnects

Abstract: Silicon photonics enables the fabrication of on-chip, ultrahigh-bandwidth optical networks that are critical for the future of microelectronics1,2,3 Several optical components necessary for implementing a wavelength division multiplexing network have been demonstrated in silicon However, a fully integrated multiple-wavelength source capable of driving such a network has not yet been realized Optical amplification, a necessary component for lasing, has been achieved on-chip through stimulated Raman scattering4,5, parametric mixing6 and by silicon nanocrystals7 or nanopatterned silicon8 Losses in most of these structures have prevented oscillation Raman oscillators have been demonstrated9,10,11, but with a narrow gain bandwidth that is insufficient for wavelength division multiplexing Here, we demonstrate the first monolithically integrated CMOS-compatible source by creating an optical parametric oscillator formed by a silicon nitride ring resonator on silicon The device can generate more than 100 new wavelengths with operating powers below 50 mW This source can form the backbone of a high-bandwidth optical network on a microelectronic chip A monolithically integrated CMOS-compatible source is demonstrated using an optical parametric oscillator based on a silicon nitride ring resonator on silicon Generating more than 100 wavelengths simultaneously and operating at powers below 50 mW, scientists say that it may form the basis of an on-chip high-bandwidth optical network

Silicon-chip-based ultrafast optical oscilloscope.

Abstract: The latest state-of-the-art oscilloscopes can achieve single-shot waveform measurements with a resolution of about 30 picoseconds. But ever greater telecommunication data rates and an expanding interest in ultrafast chemical and physical phenomena mean that there is now a demand for devices that measure optical waveforms with subpicosecond resolution. The sensitivity of conventional oscilloscopes is limited by the electronic bandwidth of photodetectors and circuits. Now Foster et al. demonstrate an all-optical method for real-time measurement of temporal optical waveforms with a resolution a hundredfold higher than electronic techniques. The heart of the device is a silicon photonic chip made with the same materials and techniques as standard microprocessors but which manipulates photons instead of electrons. The potential integration of this device in microelectronics could produce an instrument that could be used in many branches of science where simple measurements of optical waveforms are required. With the realization of faster telecommunication data rates and an expanding interest in ultrafast chemical and physical phenomena, it has become important to develop techniques that enable simple measurements of optical waveforms with subpicosecond resolution1. State-of-the-art oscilloscopes with high-speed photodetectors provide single-shot waveform measurement with 30-ps resolution. Although multiple-shot sampling techniques can achieve few-picosecond resolution, single-shot measurements are necessary to analyse events that are rapidly varying in time, asynchronous, or may occur only once. Further improvements in single-shot resolution are challenging, owing to microelectronic bandwidth limitations. To overcome these limitations, researchers have looked towards all-optical techniques because of the large processing bandwidths that photonics allow. This has generated an explosion of interest in the integration of photonics on standard electronics platforms, which has spawned the field of silicon photonics2 and promises to enable the next generation of computer processing units and advances in high-bandwidth communications. For the success of silicon photonics in these areas, on-chip optical signal-processing for optical performance monitoring will prove critical. Beyond next-generation communications, silicon-compatible ultrafast metrology would be of great utility to many fundamental research fields, as evident from the scientific impact that ultrafast measurement techniques continue to make3,4,5. Here, using time-to-frequency conversion6 via the nonlinear process of four-wave mixing on a silicon chip, we demonstrate a waveform measurement technology within a silicon-photonic platform. We measure optical waveforms with 220-fs resolution over lengths greater than 100 ps, which represent the largest record-length-to-resolution ratio (>450) of any single-shot-capable picosecond waveform measurement technique6,7,8,9,10,11,12,13,14,15,16. Our implementation allows for single-shot measurements and uses only highly developed electronic and optical materials of complementary metal-oxide-semiconductor (CMOS)-compatible silicon-on-insulator technology and single-mode optical fibre. The mature silicon-on-insulator platform and the ability to integrate electronics with these CMOS-compatible photonics offer great promise to extend this technology into commonplace bench-top and chip-scale instruments.

Ultrashort free-carrier lifetime in low-loss silicon nanowaveguides

Abstract: We demonstrate reduction of the free-carrier lifetime in a silicon nanowaveguide from 3 ns to 12.2 ps by applying a reverse bias across an integrated p-i-n diode. This observation represents the shortest free-carrier lifetime demonstrated to date in silicon waveguides. Importantly, the presence of the p-i-n structure does not measurably increase the propagation loss of the waveguide. We derive a figure of merit demonstrating equal dependency of the nonlinear phase shift on free-carrier lifetime and linear propagation loss.

Frequency conversion over two-thirds of an octave in silicon nanowaveguides.

Abstract: We demonstrate ultrabroad-bandwidth low-power frequency conversion of continuous-wave light in a dispersion engineered silicon nanowaveguide via four-wave mixing. Our process produces continuously tunable four-wave mixing wavelength conversion over two-thirds of an octave from 1241-nm to 2078-nm wavelength light with a pump wavelength in the telecommunications C-band.

Ultrafast waveform compression using a time-domain telescope

Abstract: Photonic systems provide access to extremely large bandwidths, which can approach a petahertz1. Unfortunately, full utilization of this bandwidth is not achievable using standard electro-optical technologies, and higher (>100 GHz) performance requires all-optical processing with nonlinear-optical elements. A solution to the implementation of these elements in robust, compact and efficient systems is emerging in photonic integrated circuits, as evidenced by their recent application in various ultrahigh-bandwidth instruments2,3,4. These devices enable the characterization of extremely complex signals by linking the high-speed optical domain with slower speed electronics. Here, we extend the application of these devices beyond characterization and demonstrate an instrument that generates complex and rapidly updateable ultrafast optical waveforms. We generate waveforms with 1.5-ps minimum features by compressing lower-bandwidth replicas created with a 10 GHz electro-optic modulator. In effect, our device allows for ultrahigh-speed direct 270 GHz modulation using relatively low speed devices and represents a new class of ultrafast waveform generators. By exploiting the nonlinearity of on-chip silicon nanowaveguides, a parametric temporal imaging system that can compress optical waveforms in time is demonstrated, enabling generation of complex and rapidly updatable ultrafast optical waveforms.

Microresonator-Based Optical Frequency Combs

Abstract: The series of precisely spaced, sharp spectral lines that form an optical frequency comb is enabling unprecedented measurement capabilities and new applications in a wide range of topics that include precision spectroscopy, atomic clocks, ultracold gases, and molecular fingerprinting. A new optical frequency comb generation principle has emerged that uses parametric frequency conversion in high resonance quality factor (Q) microresonators. This approach provides access to high repetition rates in the range of 10 to 1000 gigahertz through compact, chip-scale integration, permitting an increased number of comb applications, such as in astronomy, microwave photonics, or telecommunications. We review this emerging area and discuss opportunities that it presents for novel technologies as well as for fundamental science.

Temporal solitons in optical microresonators

Abstract: Temporal dissipative solitons are observed in a nonlinear, high-finesse, optical microresonator driven by a continuous-wave laser. This approach enables ultrashort pulses to be generated in spectral regimes lacking broadband laser gain media and saturable absorbers, making it potentially useful for applications in broadband spectroscopy, telecommunications, astronomy and low-phase-noise microwave generation.

New CMOS-compatible platforms based on silicon nitride and hydex for nonlinear optics

Abstract: Nonlinear photonic chips can generate and process signals all-optically with far superior performance to that possible electronically — particularly with respect to speed. Although silicon-on-insulator has been the leading platform for nonlinear optics, its high two-photon absorption at telecommunication wavelengths poses a fundamental limitation. We review recent progress in non-silicon CMOS-compatible platforms for nonlinear optics, with a focus on Si3N4 and Hydex®. These material systems have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement. We highlight their potential future impact as well as the challenges to achieving practical solutions for many key applications. This article reviews recent progress in the use of silicon nitride and Hydex as non-silicon-based CMOS-compatible platforms for nonlinear optics. New capabilities such as on-chip optical frequency comb generation, ultrafast optical pulse generation and measurement using these materials, and their potential future impact and challenges are covered.

Nonlinear silicon photonics

Abstract: The nonlinearities in silicon are diverse. This Review covers the wealth of nonlinear effects in silicon and highlights the important applications and technological solutions in nonlinear silicon photonics. The increasing capability for manufacturing a wide variety of optoelectronic devices from polymer and polymer–silicon hybrids, including transmission fibre, modulators, detectors and light sources, suggests that organic photonics has a promising future in communications and other applications.

Dissipative Kerr Solitons in Optical Microresonators

Abstract: The development of compact, chip-scale optical frequency comb sources (microcombs) based on parametric frequency conversion in microresonators has seen applications in terabit optical coherent communications, atomic clocks, ultrafast distance measurements, dual-comb spectroscopy, and the calibration of astophysical spectrometers and have enabled the creation of photonic-chip integrated frequency synthesizers. Underlying these recent advances has been the observation of temporal dissipative Kerr solitons in microresonators, which represent self-enforcing, stationary, and localized solutions of a damped, driven, and detuned nonlinear Schrodinger equation, which was first introduced to describe spatial self-organization phenomena. The generation of dissipative Kerr solitons provide a mechanism by which coherent optical combs with bandwidth exceeding one octave can be synthesized and have given rise to a host of phenomena, such as the Stokes soliton, soliton crystals, soliton switching, or dispersive waves. Soliton microcombs are compact, are compatible with wafer-scale processing, operate at low power, can operate with gigahertz to terahertz line spacing, and can enable the implementation of frequency combs in remote and mobile environments outside the laboratory environment, on Earth, airborne, or in outer space.