672 research outputs found
High-speed low-voltage electro-optic modulator with a polymer-infiltrated silicon photonic crystal waveguide
No full textThe paper concerns the design and the study of a silicon-based electro-optical modulator, using a photonic crystal waveguide containing a slot which is infiltrated with a nonlinear polymer. The research topic is important for the physics of photonic systems and for applications to integrated optics and to telecommunications.
Abstract: A novel electro-optic silicon-based modulator with a bandwidth of 78GHz, a drive voltage amplitude of 1V and a length of only 80 μm is proposed. Such record data allow 100Gbit/s transmission and can be achieved by exploiting a combination of several physical effects. First, we rely on the fast and strong nonlinearities of polymers infiltrated into silicon, rather than on the slower free-carrier effect in silicon. Second, we use a Mach-Zehnder interferometer with slotted slow-light waveguides for minimizing the modulator length, but nonetheless providing a long interaction time for modulation field and optical mode. Third, with this short modulator length we avoid bandwidth limitations by RC time constants. The slow-light waveguides are based on a photonic crystal. A polymer-filled narrow slot in
the waveguide center forms the interaction region, where both the optical mode and the microwave modulation field are strongly confined to. The waveguides are designed to have a low optical group velocity and negligible dispersion over a 1THz bandwidth.With an adiabatic taper we significantly enhance the coupling to the slow light mode. The feasibility of broadband slow-light transmission and efficient taper coupling has been previously demonstrated by us with calculations and microwave model experiments, where fabrication-induced disorder of the photonic crystal was taken into account
Simultaneous processing of 43 Gb/s WDM channels by a fiber-based dispersion-managed 2R regenerator
No full textWe demonstrate 43 Gb/s multi-channel 2R regeneration in a single dispersion-managed fiber, based on SPM-induced spectral broadening and subsequent offset filtering
All-fiberized dispersion-managed multi-channel regeneration at 43 Gb/s
No full textWe report on the simultaneous 2R regeneration of up to three 42.7 Gb/s wavelength-division-multiplexing channels in a simple dispersion-managed fiber section with signal quality improvements higher than 1.7 dB. The regenerator relies on self-phase modulation-induced spectral broadening of the optical channels inside the fiber section and subsequent bandpass filtering at shifted wavelengths, and it is experimentally investigated in single-, dual-, and three-channel operation using optical pulses of 33% duty cycle
Tunable Diode-Laser Absorption Spectroscopy for Trace-Gas Measurements with High Sensitivity and Low Drift
No full textThis book discusses the mechanical and opto-electronic design of laser spectrometers for measuring two very important atmospheric gases, namely water vapor and its isotopic ratios, and formaldehyde. For measuring water vapor, shot-noise limited sensitivity has been achieved by a careful choice of system components and data processing. For measuring formaldehyde, a selective sample modulation exploiting the Stark effect has been used to greatly improve the sensitivity
Optically Powered Highly Energy-efficient Sensor Networks
No full textIn optically powered networks, both, communication signals and power for remotely located sensor nodes, are transmitted over an optical fiber. Key features of optically powered networks are node operation without local power supplies or batteries as well as operation with negligible susceptibility to electro-magnetic interference and to lightning. In this book, different kinds of optically powered devices and networks are investigated, and selected applications are demonstrated
Nanophotonic Devices for Linear and Nonlinear Optical Signal Processing
No full textHigh index-contrast nanophotonic devices are key components for future board-to-board and chip-to-chip optical interconnects: The strong confinement of light enables dense integration, and nonlinear effects can be exploited at low power levels. Cheap large-scale production is possible by using highly parallel microfabrication techniques, and semiconductor-based nanophotonic devices can be integrated together with electronic circuitry on a common chip. Particularly intense research is carried out to realise optical devices on silicon substrates, using mature complementary metal-oxide-semiconductor (CMOS) fabrication techniques.
This book discusses the modelling, fabrication and characterization of linear and nonlinear nanophotonic devices. Roughness-related scattering loss in high index-contrast waveguides is investigated both theoretically and experimentally, and methods of loss reduction are developed. Novel silicon-based devices for electro-optic modulation and for all-optical signal processing are presented. Nonlinear dynamics in active quantum-dot devices are studied, and resonant field enhancement is exploited to improve the efficiency of nonlinear interaction
Millimeter-Precision Laser Rangefinder Using a Low-Cost Photon Counter
No full textIn this book we successfully demonstrate a millimeter-precision laser rangefinder using a low-cost photon counter. An application-specific integrated circuit (ASIC) comprises timing circuitry and single-photon avalanche diodes (SPADs) as the photodetectors. For the timing circuitry, a novel binning architecture for sampling the received signal is proposed which mitigates non-idealities that are inherent to a system with SPADs and timing circuitry in one chip
Efficient modulation cancellation using reflective SOAs
No full textModulation cancellation and signal inversion are demonstrated within reflective semiconductor optical amplifiers. The effect is necessary to implement colorless optical network units for network end-users, where downstream signals need to be erased in order to reuse the carrier for upstream transmission. The results presented here indicate that reflective semiconductor optical amplifiers possess the perfect high-speed all-optical gain saturation characteristics to completely cancel the downstream modulation at microwatt optical power levels and are thus the prime candidate to be constituents of future optical network units. Theoretical considerations are supported by experiments that show the cancellation of signals with a 6 dB extinction ratio at 2.5 Gbit/s. © 2012 Optical Society of America
Slow-light photonic crystal devices for high-speed optical signal processing
No full textThis book discusses design, modeling, and the characterization of slow-light photonic crystal waveguides. Guidelines are developed to obtain slow-light waveguides with broadband characteristics and with low disorder-induced losses. Three functional devices are proposed and studied: A tunable dispersion compensator, a tunable optical delay line, and a high-speed electro-optic modulator. Optical and microwave measurements confirm the designs
Pattern effect mitigation techniques for all-optical wavelength converters based on semiconductor optical amplifiers
No full textAll-optical wavelength converters (AOWC) are considered key to overcome wavelength blocking issues in next generation transparent networks. The focus of this book is on semiconductor optical amplifiers (SOA), a mature nonlinear element with very favorable nonlinear characteristics, and on a discussion of various filter configurations as well as on their adaptations for providing optimum performance matched to the nonlinear element working in high-speed all-optical wavelength converters
- …
