Showing papers by "Michael Hochberg published in 2010"

Label-Free Biosensor Arrays Based on Silicon Ring Resonators and High-Speed Optical Scanning Instrumentation

Abstract: A platform for performing rapid, real-time binding assays on sensor arrays based on silicon ring resonators is presented in this paper. An array of 32 sensors is interrogated simultaneously. Using eight sensors as controls, 24 simultaneous binding curves are produced. The bulk refractive index sensitivity of the system was demonstrated down to 7.6 × 10-7 and sensor-to-sensor variability is 3.9%. Using an 8-min incubation, real-time binding was observed over 8-logs of concentration down to 60 fM using immobilized biotin to capture streptavidin diluted in bovine serum albumin solution. Multiplexing in complex media is demonstrated with two DNA oligonucleotide probes. Time to result and repeatability are demonstrated to be adequate for clinical applications.

Towards fabless silicon photonics

Abstract: Silicon photonic devices can be built using commercial CMOS chip fabrication facilities, or 'fabs'. However, nearly all research groups continue to design, build and test chips internally, rather than leveraging shared CMOS foundry infrastructure.

Silicon-on-sapphire integrated waveguides for the mid-infrared.

Abstract: Silicon waveguides are now widely used to guide radiation in the near-infrared, mainly in the wavelength range of 1.1 – 2.2 µm. While low-loss waveguides at longer wavelengths in silicon have been proposed, experimental realization has been elusive. Here we show that single-mode integrated silicon-on-sapphire waveguides can be used at mid-infrared wavelengths. We demonstrate waveguiding at 4.5 µm, or 2222.2 cm−1, with losses of 4.3 ± 0.6 dB/cm. This result represents the first practical integrated waveguide system for the mid-infrared in silicon, and enables a range of new applications.

Demonstration of a low V pi L modulator with GHz bandwidth based on electro-optic polymer-clad silicon slot waveguides.

Abstract: We demonstrate a near-infrared electro-optic modulator with a bandwidth of 3 GHz and a VπL figure of merit of 0.8 V-cm using a push-pull configuration. This is the highest operating speed achieved in a silicon-polymer hybrid system to date by several orders of magnitude. The modulator was fabricated from a silicon strip-loaded slot waveguide and clad in a nonlinear polymer. In this geometry, the electrodes form parts of the waveguide, and the modulator driving voltage drops across a 200 nm slot.

Silicon waveguides and ring resonators at 5.5 μm

Abstract: We demonstrate low loss ridge waveguides and the first ring resonators for the mid-infrared, for wavelengths ranging from 5.4 to 5.6 μm. Structures were fabricated using electron-beam lithography on the silicon-on-sapphire material system. Waveguide losses of 4.0±0.7 dB/cm are achieved, as well as Q-values of 3.0 k.

Silicon Waveguides and Ring Resonators at 5.5 {\mu}m

Abstract: We demonstrate low loss ridge waveguides and the first ring resonators for the mid-infrared, for wavelengths ranging from 5.4 to 5.6 {\mu}m. Structures were fabricated using electron-beam lithography on the silicon-on-sapphire material system. Waveguide losses of 4.0 +/- 0.7 dB/cm are achieved, as well as Q-values of 3.0 k.

Design of transmission line driven slot waveguide Mach-Zehnder interferometers and application to analog optical links

Abstract: Slot waveguides allow joint confinement of the driving electrical radio frequency field and of the optical waveguide mode in a narrow slot, allowing for highly efficient polymer based interferometers. We show that the optical confinement can be simply explained by a perturbation theoretical approach taking into account the continuity of the electric displacement field. We design phase matched transmission lines and show that their impedance and RF losses can be modeled by an equivalent circuit and linked to slot waveguide properties by a simple set of equations, thus allowing optimization of the device without iterative simulations. We optimize the interferometers for analog optical links and predict record performance metrics (Vπ = 200 mV @ 10 GHz in push-pull configuration) assuming a modest second order nonlinear coefficient (r33 = 50 pm/V) and slot width (100 nm). Using high performance optical polymers (r33 = 150 pm/V), noise figures of state of the art analog optical links can be matched while reducing optical power levels by approximately 30 times. With required optical laser power levels predicted at 50 mW, this could be a game changing improvement by bringing high performance optical analog link power requirements in the reach of laser diodes. A modified transmitter architecture allows shot noise limited performance, while reducing power levels in the slot waveguides and enhancing reliability.

Low-loss strip-loaded slot waveguides in silicon-on-insulator.

Abstract: Electro-optic polymer-clad silicon slot waveguides have recently been used to build a new class of modulators, that exhibit very high bandwidths and extremely low drive voltages. A key step towards making these devices practical will be lowering optical insertion losses. We report on the first measurements of low-loss waveguides that are geometrically suitable for high bandwidth slot waveguide modulators: a strip-loaded slot waveguide. Waveguide loss for undoped waveguides of 6.5 ± 0.2 dB/cm was achieved with 40 nm thick strip-loading, with the full silicon thickness around 220 nm and a slot size of 200 nm, for wavelengths near 1550 nm.

Silicon waveguides and ring resonators at 5.5 µm

Abstract: We fabricate and characterize silicon waveguides and ring resonators around 5.5 µm on the Silicon-on-Sapphire (SOS) platform. The waveguide loss is 4.1 ± 0.7 dB/cm, and a Q value of 1.4k is achieved.

Silicon-graphene waveguide photodetectors, optically active elements and microelectromechanical devices

Abstract: Systems and methods for modulating light with light in high index contrast waveguides clad with graphene. Graphene exhibits a large nonlinear electro-optic constant χ 3 . Waveguides fabricated on SOI wafers and clad with graphene are described. Systems and methods for modulating light with light are discussed. Optical logic gates are described. Waveguides having closed loop structures such as rings and ovals, Mach-Zehnder interferometer, grating, and Fabry-Perot configurations, are described. Optical signal processing methods, including optical modulation at Terahertz frequencies, are disclosed. Optical detectors are described. Microelectromechanical and nanoelectromechanical systems using graphene on silicon substrates are described.

Geometries for electrooptic modulation with χ2 materials in silicon waveguides

Abstract: An apparatus for providing electrooptic modulation. The apparatus includes electrical contacts, a waveguide coupled between the electrical contacts, and a nonlinear optical material positioned in the slot region. The waveguide includes a first arm and a second arm that are each arranged to define a slot region for confining an optical mode. The slot region has a height, t 1 , and each of the first arm and the second arm include a strip load region having a height that is less than the height, t 1 , of the slot region. Each of the first arm and the second arm is configured to provide an electrical signal to the slot region via at least one of the electrical contacts. In one embodiment, the nonlinear optical material includes a χ 2 -based material. In another embodiment, each of the first arm and the second arm have an “L”-type shape.

Sub-Volt Silicon-Organic Electrooptic Modulator

Abstract: Lowering the operating voltage of electrooptic modulators is desirable for a variety of applications, most notably in analog photonics , and digital data communications . In particular for digital systems such as CPUs, it is desirable to develop modulators that are both temperature-insensitive and compatible with typically sub-2V CMOS electronics ; however, drive voltages in silicon-based MZIs currently exceed 6.5V . Here we show an MZI modulator based on an electrooptic polymer-clad silicon slot waveguide, with a halfwave voltage of only 0.69V, and a bandwidth of 500 MHz. We also show that there are also paths to significantly improve both the bandwidth and drive voltage . Our silicon-organic modulator has an intrinsic power consumption less than 0.66 pJ/bit, nearly an order of magnitude improvement over the previous lowest energy silicon MZI .

Nanogap quantum dot photodetectors with high sensitivity and bandwidth

Abstract: We report high-performance nanoscale photodetectors utilizing annealed nanocrystal quantum dots (QDs) within a nanoscale metal electrode gap. By optimizing the nanogap size and fabrication process, the device demonstrates a significantly better sensitivity (noise equivalent power=7.76×10−14 W/Hz1/2) and bandwidth (≥125 kHz) than previously reported nanoscale photodetectors. Furthermore, by utilizing a lateral photoconduction structure and a self-assembled layer of QDs, the detector fabrication is highly compatible with many substrates and device architectures.

Silicon photonics: On-chip OPOs

Abstract: Optical parametric oscillators (OPOs) have now been realized in a CMOS-style process by exploiting nonlinear four-wave mixing. Such multiwavelength sources bring the prospect of ultrafast chip-to-chip optical data communications a step closer.

Effective χ2 on the basis of electric biasing of χ3 materials

Abstract: A method for controlling the nonlinear moments of a nonlinear optical material of an electrooptical device is disclosed. The method includes controlling an optical mode region of the electrooptical device by providing a time varying signal to the electrooptical device via one or more electrodes of the device and affecting the nonlinear moments of the nonlinear optical material of the electrooptical device by providing a time independent bias to the device. In one embodiment, the nonlinear optical material includes a χ 3 material. In another embodiment, the method includes employing the time independent bias to bias the χ 3 material such that the χ 3 material behaves in a manner analogous to a χ 2 material.

All-optical high bandwidth sampling device based on a third-order optical nonlinearity

Abstract: An all-optical sampling device using four-wave mixing in third-order optically nonlinear materials is described. The four-wave mixing based sampler comprises a waveguide combiner, which adds a gate optical signal to a signal of interest to be sampled. In a four-wave mixing region, a sampled signal at the output optical frequency is produced. All of the optical signals are sent to a passive optical filter, which preferentially discards the gate and signal optical frequencies, but preserves the sampled signal at the output optical frequency. The sampled signal at the output optical frequency can be observed, displayed, recorded or otherwise manipulated.

Theoretical Study of Optical Rectification at Radio Frequencies in a Slot Waveguide

Abstract: We present a theoretical study of optical rectification (OR) at radio frequencies (RF). OR is a process by which a second-order nonlinear optical material can directly convert an optical field into an RF electric field. The combination of high-index nanoscale waveguides and new optical materials allow this effect to be greatly enhanced. We develop a lumped-element equivalent circuit model for the OR process from first principles, which enables the power conversion and bandwidth of the effect to be predicted. We use our model to predict that significant amounts of RF power should be obtainable from a slot waveguide device clad in a nonlinear optical polymer. Based on our model, we estimate that OR-based photodetectors may be possible, operating at speeds of 400 GHz, with responsivities on the order of 9 mA/W.

A low V π L modulator with GHz bandwidth based on an electro-optic polymer-clad silicon slot waveguide

Abstract: We demonstrate a near-infrared modulator with a bandwidth exceeding 1GHz, based on a silicon strip-loaded slot waveguide clad in a nonlinear electro-optic polymer. Our device achieves a V π L figure of merit of 0.8V-cm.

Semiconductor travelling-wave evanescent waveguide photodetector

Abstract: An optoelectronic structure includes a waveguide region, a detector region that is weakly evanescently coupled to the waveguide region, and a dielectric layer interposed between the waveguide region and the detector region and configured to provide the weak evanescent coupling.

Low-noise and high bandwidth electric field sensing with silicon-polymer integrated photonics and low drive voltage modulator fiber-based antenna link

Abstract: An optical low drive voltage modulator electric field sensor device includes an electric field antenna. A low drive voltage modulator has an electrical voltage input electrically coupled to the electric field antenna, a light input, and a modulated light output. The optical low drive voltage modulator electric field sensor is configured to provide an optical output signal at the modulated light output having an optical parameter responsive to an electric field at the electric field antenna. The optical low drive voltage modulator electric field sensor device can also be configured to provide an RF output signal at a location physically remote from said antenna, where the RF output signal is responsive to an electromagnetic wave received at a remote antenna.

Fabricating waveguides in conjunction with interconnect fabrication in back-ends of integrated circuits and structures thereof

Abstract: Methods for fabricating waveguides in conjunction with interconnect fabrication in back-ends of integrated circuits and structures thereof are disclosed. One method for forming a waveguide in accordance with one embodiment of the disclosure comprises selectively etching a dielectric layer and forming of a core region of a waveguide at a back-end of an integrated circuit. The dielectric layer is material deposited during a cycle of fabrication of the back-end of the integrated circuit. The method further includes depositing a material having a dielectric constant that is suitable to be the core region of the waveguide cladded by the dielectric layer over the dielectric layer and into the etched feature for the core region of the waveguide, and planarizing a surface of the material.

Ultra-low V ? slot Waveguide Based Interferometers with ? 2 Nonlinear Polymers

Abstract: Slot waveguides allow joint confinement of the RF electrical and optical-fields in a narrow slot and enable ultra-low driving-voltage polymer-based modulators. We show recent progress with transmission line driven devices and application to analog-optical links.

Design of high-speed ultra-low V π slot waveguide modulators

Abstract: Slot waveguides allow joint confinement of the RF electrical and optical fields in a narrow slot and enable ultra-low driving voltage polymer based modulators with projected Vπ below 250 mV for 10 GHz devices.