Showing papers in "IEEE Journal of Selected Topics in Quantum Electronics in 2010"
TL;DR: In this article, a theoretical analysis of the dual-polarization constant modulus algorithm is presented, where the control surfaces several different equalizer algorithms are derived, including the decision-directed, trained, and the radially directed equalizer for both polarization division multiplexed quadriphase shift keyed (PDM-QPSK) and 16 level quadrature amplitude modulation (PDm-16-QAM).
Abstract: Digital coherent receivers have caused a revolution in the design of optical transmission systems, due to the subsystems and algorithms embedded within such a receiver. After giving a high-level overview of the subsystems, the optical front end, the analog-to-digital converter (ADC) and the digital signal processing (DSP) algorithms, which relax the tolerances on these subsystems are discussed. Attention is then turned to the compensation of transmission impairments, both static and dynamic. The discussion of dynamic-channel equalization, which forms a significant part of the paper, includes a theoretical analysis of the dual-polarization constant modulus algorithm, where the control surfaces several different equalizer algorithms are derived, including the constant modulus, decision-directed, trained, and the radially directed equalizer for both polarization division multiplexed quadriphase shift keyed (PDM-QPSK) and 16 level quadrature amplitude modulation (PDM-16-QAM). Synchronization algorithms employed to recover the timing and carrier phase information are then examined, after which the data may be recovered. The paper concludes with a discussion of the challenges for future coherent optical transmission systems.
772 citations
TL;DR: A platform for real-time binding assays on sensor arrays based on silicon ring resonators is presented in this article, where an array of 32 sensors is interrogated simultaneously and 24 simultaneous binding curves are produced.
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.
553 citations
TL;DR: In this paper, the authors give an overview of recent progress in passive spectral filters and demultiplexers based on silicon-on-insulator photonic wire waveguides: ring resonators, interferometers, arrayed waveguide gratings, and echelle diffraction gratings.
Abstract: We give an overview of recent progress in passive spectral filters and demultiplexers based on silicon-on-insulator photonic wire waveguides: ring resonators, interferometers, arrayed waveguide gratings, and echelle diffraction gratings, all benefit from the high-index contrast possible with silicon photonics. We show how the current generation of devices has improved crosstalk levels, insertion loss, and uniformity due to an improved fabrication process based on 193 nm lithography.
470 citations
TL;DR: In this paper, the authors report sub-nanometer linewidth uniformity in silicon nanophotonics devices fabricated using high-volume CMOS fabrication tools, using wavelength-selective devices such as ring resonators, Mach-Zehnder interferometers, and arrayed waveguide gratings to assess the device nonuniformity within and between chips.
Abstract: We report subnanometer linewidth uniformity in silicon nanophotonics devices fabricated using high-volume CMOS fabrication tools. We use wavelength-selective devices such as ring resonators, Mach-Zehnder interferometers, and arrayed waveguide gratings to assess the device nonuniformity within and between chips. The devices were fabricated using 193 or 248 nm optical lithography and dry etching in silicon-on-insulator wafer technology. Using 193 nm optical lithography, we have achieved a linewidth uniformity of 2 nm (after lithography) and 2.6 nm (after dry etch) over 200 mm wafer. Furthermore, with the developed fabrication process, using wavelength-selective devices, we have demonstrated a linewidth control better than 0.6 nm within chip and better than 2 nm chip-to-chip. The necessity for high-resolution optical lithography is demonstrated by comparing device nonuniformity between the 248 and 193 nm optical lithography processes.
311 citations
TL;DR: In this paper, a low-thermal-budget postepitaxy anneal was introduced to improve the performance of the Ge photodetectors, thus resulting in significantly improved dark current.
Abstract: Si modulators and Ge photodetectors are monolithically integrated on Si-on-insulator. The carrier-depletion-type Si modulators achieved high modulation efficiency and speed (V ? L ? = 2.56 V·cm, 10 Gb/s). Low-voltage operation (V RF = 1 V pp) was also demonstrated. Introducing a low-thermal-budget postepitaxy anneal improves the performance of the Ge photodetectors, thus resulting in significantly improved dark current. The responsivity and speed in the low-voltage regime are also enhanced, which enhances low-voltage or even short-circuit (V Bias = 0 V) operation.
275 citations
TL;DR: In this article, the trends, architecture, and performance of wavelength-selective switches (WSS) are analyzed in the context of their application to reconfigurable optical add/drop multiplexer (ROADM)-based optical networks.
Abstract: The trends, architecture, and performance of wavelength-selective switches (WSS) are analyzed in the context of their application to reconfigurable optical add/drop multiplexer (ROADM)-based optical networks. The resulting analyses define the requirements for the latest generation of ROADM systems and provide insight into the critical specifications of this technology. In addition, the current trends for WSS technology are reviewed in the context of synergies with the strengths of different switching technologies.
199 citations
TL;DR: The performance of advanced modulation schemes for spectrally efficient data transmission is reviewed, targeting short-range intensity-modulated optical channels with direct detection and it is found that even symmetrically clipped discrete multitone suffers from its large crest factor in the peak-power-limited channel and that pulse-amplitude modulation provides higher link margins for the same target bit-error probability.
Abstract: The performance of advanced modulation schemes for spectrally efficient data transmission is reviewed, targeting short-range intensity-modulated optical channels with direct detection. Hereby, the focus lies on the performance of multilevel pulse-amplitude modulation combined with electronic equalization and, as an alternative modulation scheme, discrete multitone. A comprehensive statistical analysis of clipping noise is presented and exact expressions for the performance of symmetrically clipped discrete multitone are derived. It is shown that the clipping noise is impulsive and obeys a generalized Laplace distribution. The bit-error probability due to clipping is studied in detail, and it is found that the impact of clipping noise is reduced for an increasing number of subchannels. Finally, the optical link margins of multilevel pulse-amplitude modulation in combination with electronic equalization and that of discrete multitone in combination with margin-adaptive bit loading are compared. It is found that even symmetrically clipped discrete multitone suffers from its large crest factor in the peak-power-limited channel and that, in many instances, pulse-amplitude modulation provides higher link margins for the same target bit-error probability.
184 citations
TL;DR: In this paper, a new silicon depletion-mode vertical p-n junction phase-modulator implemented in Mach-Zehnder modulator configuration, enabling an ultralow measured V? L of only ~ 1 V·cm.
Abstract: Through rigorous process, electrical, and optical simulations, we develop a new silicon depletion-mode vertical p-n junction phase-modulator implemented in Mach-Zehnder modulator configuration, enabling an ultralow measured V ? L of only ~ 1 V·cm. Further, in a 500-?m-long lumped element device, we demonstrate a 10-Gb/s nonreturn-to-zero data transmission with wide-open complementary output eye diagrams without the use of signal preemphasis.
184 citations
TL;DR: Recent state-of-the-art research on the enabling technologies needed to realize future WDM-PON and WDM/TDM-Pon systems are reviewed, and future directions toward practical PON systems are discussed.
Abstract: Wavelength-division multiplexing (WDM) technologies are expected to play a key role in realizing the next generation scalable and flexible passive optical networks (PONs). One candidate is WDM-PON, in which each optical network unit (ONU) uses a different wavelength, i.e., a unique wavelength, in each direction to communicate with the optical line terminal. Another candidate is WDM/time-division multiplexing (TDM)-PON; it combines WDM with TDM technology. This paper reviews recent state-of-the-art research on the enabling technologies needed to realize future WDM-PON and WDM/TDM-PON systems, and discusses future directions toward practical PON systems.
171 citations
TL;DR: In this paper, a simple electric-circuit description of the split-ring resonator is used to give a basic introduction to the cross terms, and mathematical details of the effective parameter retrieval are presented.
Abstract: In metamaterials, electric (magnetic) dipoles can be excited by the electric (magnetic) component of the incident light field. Moreover, in the description of bianisotropic metamaterials, cross terms occur, i.e., magnetic dipoles can also be excited by the electric-field component of the incident light and vice versa. For the cross terms, in the general bianisotropic case, the exciting field and dipole vectors include an arbitrary angle. For the special case of chirality, the angle is zero. In the spirit of a brief tutorial, a very simple electric-circuit description of the split-ring resonator is used to give a basic introduction to the cross terms. Mathematical details of the effective parameter retrieval are presented. Furthermore, we briefly review recent experiments on bianisotropic metamaterials operating at optical frequencies.
167 citations
TL;DR: An overview of digital equalization algorithms for coherent receivers and derive expressions for their complexity is given, which compare single-carrier and multicarrier approaches, and investigates blind equalizer adaptation as well as training-symbol-based algorithms.
Abstract: Digital signal processing has completely changed the way optical communication systems work during recent years. In combination with coherent demodulation, it enables compensation of optical distortions that seemed impossible only a few years ago. However, at high bit rates, this comes at the price of complex processing circuits and high power consumption. In order to translate theoretic concepts into economically viable products, careful design of the digital signal processing algorithms is needed. In this paper, we give an overview of digital equalization algorithms for coherent receivers and derive expressions for their complexity. We compare single-carrier and multicarrier approaches, and investigate blind equalizer adaptation as well as training-symbol-based algorithms. We examine tradeoffs between parameters like sampling rate and tracking speed that are important for algorithm design and practical implementation.
TL;DR: Si-based plasmonics have the potential to not only reduce the size of photonic components to deeply subwavelength scales, but also to enhance the emission, detection, and manipulation of optical signals in Si.
Abstract: Silicon-based photonic devices dissipate substantially less power and provide a significantly greater information bandwidth than electronic components. Unfortunately, large-scale integration of photonic devices has been limited by their large, wavelength-scale size and the weak optical response of Si. Surface plasmons may overcome these two limitations. Combining the high localization of electronic waves with the propagation properties of optical waves, plasmons can achieve extremely small mode wavelengths and large local electromagnetic field intensities. Si-based plasmonics has the potential to not only reduce the size of photonic components to deeply subwavelength scales, but also to enhance the emission, detection, and manipulation of optical signals in Si. In this paper, we discuss recent advances in Si-based plasmonics, including subwavelength interconnects, modulators, and emission sources. From scales spanning slab waveguides to single nanocrystals, we show that Si-based plasmonics can enable optical functionality competitive in size and speed with contemporary electronic components.
TL;DR: The authors' measurements suggest the integrated chip is capable of transmitting data at an aggregate rate of 200 Gb/s, which represents a key milestone on the way for fabricating terabit per second transceiver chips to meet the demand of future terascale computing.
Abstract: We review recent advances in the development of silicon photonic integrated circuits for high-speed and high-capacity interconnect applications. We present detailed design, fabrication, and characterization of a silicon integrated chip based on wavelength division multiplexing. In such a chip, an array of eight high-speed silicon optical modulators is monolithically integrated with a silicon-based demultiplexer and a multiplexer. We demonstrate that each optical channel operates at 25 Gb/s. Our measurements suggest the integrated chip is capable of transmitting data at an aggregate rate of 200 Gb/s. This represents a key milestone on the way for fabricating terabit per second transceiver chips to meet the demand of future terascale computing.
TL;DR: In this article, the state of the art in advanced InP photonic ICs is reviewed for the 1.3-1.6 m wavelength optical fiber optical fiber. And the authors present a survey of the state-of-the-art in InP ICs.
Abstract: InP is an ideal integration platform for optical generation, switching, and detection components operating in the range of 1.3-1.6 m wavelength, which is preferred for data transmission in the most prevalent silica-based optical fiber. We review the current state of the art in advanced InP photonic ICs.
TL;DR: In this article, a summary of recent experiments showing how various nonlinear phenomena are enhanced due to slow light in silicon photonic crystal waveguides is presented, including self-phase modulation (SPM), two-photon absorption (TPA), free-carrier related effects, and third-harmonic generation.
Abstract: We present a summary of our recent experiments showing how various nonlinear phenomena are enhanced due to slow light in silicon photonic crystal waveguides. These nonlinear processes include self-phase modulation (SPM), two-photon absorption (TPA), free-carrier related effects, and third-harmonic generation, the last effect being associated with the emission of green visible light, an unexpected phenomenon in silicon. These demonstrations exploit photonic crystal waveguides engineered to support slow modes with a range of group velocities as low as c/50 and, more crucially, with significantly reduced dispersion. We discuss the potential of slow light in photonic crystals for realizing compact nonlinear devices operating at low powers. In particular, we consider the application of SPM to all-optical regeneration, and experimentally investigate an original approach, where enhanced TPA and free-carrier absorption are used for partial regeneration of a high-bit rate data stream (10 Gb/s).
TL;DR: Investigating the influence of the atmosphere, background light, and flight qualification requirements on system design, it is explained why the data rates in free-space optical communications are still significantly below those possible in today's terrestrial fiber-based systems.
Abstract: This paper contains a review of technologies, theoretical studies, and experimental field trials for optical communications from and to high-altitude platforms (HAPs). We discuss the pointing, acquisition, and tracking of laser terminals and describe how laser beams with low divergence can be used to transmit data at multi-Gigabits per second. Investigating the influence of the atmosphere, background light, and flight qualification requirements on system design, we explain why the data rates in free-space optical communications are still significantly below those possible in today's terrestrial fiber-based systems. Techniques like forward-error correction, adaptive optics, and diversity reception are discussed. Such measures help to increase the data rate or link distance while keeping the bit error ratio and outage probability of the optical HAP communication system low.
TL;DR: The performance of the receiver using a digital backpropagation algorithm with varying nonlinear step size is characterized to determine an upper bound on the suppression of intrachannel nonlinearities in a single-channel system.
Abstract: Coherent detection with receiver-based DSP has recently enabled the mitigation of fiber nonlinear effects. We investigate the performance benefits available from the backpropagation algorithm for polarization division multiplexed quadrature amplitude phase-shift keying (PDM-QPSK) and 16-state quadrature amplitude modulation (PDM-QAM16). The performance of the receiver using a digital backpropagation algorithm with varying nonlinear step size is characterized to determine an upper bound on the suppression of intrachannel nonlinearities in a single-channel system. The results show that for the system under investigation PDM-QPSK and PDM-QAM16 have maximum step sizes for optimal performance of 160 and 80 km, respectively. Whilst the optimal launch power is increased by 2 and 2.5 dB for PDM-QPSK and PDM-QAM16, respectively, the Q-factor is correspondingly increased by 1.6 and 1 dB, highlighting the importance of studying nonlinear compensation for higher level modulation formats.
TL;DR: In this article, the effect of strain, doping, and temperature on the direct-gap optical gain in germanium was discussed and compared with the results from fabricated Ge/Si heterojunction LEDs.
Abstract: It has been demonstrated theoretically and experimentally that germanium, with proper strain engineering and n-type doping, can be an efficient light emitter and a gain medium at its direct bandgap within the third optical communication window ( ~1520-1620 nm). In this paper, we systematically discuss the effect of strain, doping, and temperature on the direct-gap optical gain in germanium. For electrically pumped devices, properties and design guidelines of Ge/Si heterojunction are also analyzed and compared with the results from fabricated Ge/Si heterojunction LEDs.
TL;DR: Experimental measurements on fabricated silicon photonic devices verify the feasibility of the proposed system architecture, while previous works have verified its efficacy.
Abstract: The stringent on- and off-chip communications demands of future-generation chip multiprocessors require innovative and potentially disruptive technology solutions, such as chip-scale photonic transmission systems. A space-switched, wavelength-parallel photonic network-on-chip has been shown to equip users with high-bandwidth, low-latency links in an energy-efficient manner. Here, experimental measurements on fabricated silicon photonic devices verify a large set of the components needed to construct these networks. The proposed system architecture is reviewed to motivate the demanding performance requirements of the components. Then, systems-level investigations are delineated for multiwavelength electrooptic modulators and photonic switching elements arranged in 1 × 2, 2 × 2, and 4 × 4 formations. Compact (~10 ?m), high-speed (4 Gb/s) modulators, having a large degree of channel scalability (four channels demonstrated), are demonstrated with excellent data integrity (bit error rates (BERs) 10 dB). Data integrity is also verified for the switches (BERs < 10-12) with power penalty measurements amid dynamic operation. These network component demonstrations verify the feasibility of the proposed system architecture, while previous works have verified its efficacy.
TL;DR: Optical microangiography is a recently developed volumetric imaging technique that is capable of producing 3-D images of dynamic blood perfusion within microcirculatory tissue beds in vivo and its recent developments that use a constant modulation frequency introduced in the spectral interferograms to achieve the blood perfusions imaging are discussed.
Abstract: Optical microangiography (OMAG) is a recently developed volumetric imaging technique that is capable of producing 3-D images of dynamic blood perfusion within microcirculatory tissue beds in vivo . The imaging contrast of OMAG image is based on the intrinsic optical scattering signals backscattered by the moving blood cells in patent blood vessels, thus, it is a label-free imaging technique. In this paper, I will first discuss its recent developments that use a constant modulation frequency introduced in the spectral interferograms to achieve the blood perfusion imaging. I will then introduce its latest development that utilizes the inherent blood flow to modulate the spectral interferograms to realize the blood perfusion imaging. Finally, examples of using OMAG to delineate the dynamic blood perfusion, down to capillary level resolution, within living tissues are given, including cortical blood perfusion in the brain of small animals and blood flow within human retina and choroids.
TL;DR: Assessment of the composition of atherosclerotic plaques, imaging of macrophages within the plaque, and molecular imaging of biomarkers associated with formation and development of plaques are presented.
Abstract: Intravascular photoacoustic (IVPA) imaging is a catheter-based, minimally invasive, imaging modality capable of providing high-resolution optical absorption map of the arterial wall. Integrated with intravascular ultrasound (IVUS) imaging, combined IVPA and IVUS imaging can be used to detect and characterize atherosclerotic plaques building up in the inner lining of an artery. In this paper, we present and discuss various representative applications of combined IVPA/IVUS imaging of atherosclerosis, including assessment of the composition of atherosclerotic plaques, imaging of macrophages within the plaques, and molecular imaging of biomarkers associated with formation and development of plaques. In addition, imaging of coronary artery stents using IVPA and IVUS imaging is demonstrated. Furthermore, the design of an integrated IVUS/IVPA imaging catheter needed for in vivo clinical applications is discussed.
TL;DR: Currently, optimized probe approaches are showing efficacy in clinical trials, and fully commercialized imaging systems are emerging, which will clearly help to lead adoption into neurosurgical practice.
Abstract: Fluorescence imaging in neurosurgery has a long historical development, with various biomarkers and biochemical agents being used, and numerous technological approaches. This review focuses on contrast agents, summarizing endogenous fluorescence, exogenously stimulated fluorescence, and exogenous contrast agents, and then on tools used for imaging. It ends with a summary of key clinical trials that lead to consensus studies. The practical utility of protoporphyrin IX (PpIX) as stimulated by administration of δ-aminolevulinic acid has had substantial pilot clinical studies and basic science research completed. Recently, multicenter clinical trials using PpIX fluorescence to guide resection have shown efficacy for improved short-term survival. Exogenous agents are being developed and tested preclinically, and hopefully hold the potential for long-term survival benefit if they provide additional capabilities for resection of microinvasive disease or certain tumor subtypes that do not produce PpIX or help delineate low-grade tumors. The range of technologies used for measurement and imaging varies widely, with most clinical trials being carried out with either point probes or modified surgical microscopes. Currently, optimized probe approaches are showing efficacy in clinical trials, and fully commercialized imaging systems are emerging, which will clearly help to lead adoption into neurosurgical practice.
TL;DR: This preliminary pilot clinical trial results on in vivo virtual biopsy of human skin by using higher harmonic generation microscopy indicate a superior viability performance of the developed system, but also a much improved penetrability in different skin types.
Abstract: Higher harmonic generation microscopy (HHGM), combining both second- and third-harmonic generation (SHG and THG) modalities, is a new paradigm for in vivo noninvasive virtual biopsy. With the ability to achieve noninvasiveness, high resolution, and high penetrability at the same time, HHGM is a promising tool for future noninvasive diagnosis of skin diseases. In this paper, we report our preliminary pilot clinical trial results on in vivo virtual biopsy of human skin by using HHGM. In vivo virtual biopsy imaging has been performed on 21 volunteers' inside and outside forearm skin along with the damage evaluation. Together with an embryo viability study, our results not only indicate a superior viability performance of the developed system, but also a much improved penetrability in different skin types. Ex vivo studies further confirm the capability of the developed virtual biopsy system to pathohistologically distinguish different skin diseases. Our in vivo HHGM biopsy study of human skin with different colors also reveals the central role of melanin in the epi-THG resonance enhancement and attenuation. With a unique capability to molecular image the melanin distribution, epi-THG microscopy is also highly valuable for diagnosing and screening early melanocytic lesions.
TL;DR: The Twente photoacoustic mammoscope (PAM) as discussed by the authors uses pulsed light at 1064 nm to excite PA signals and uses a planar 590-element ultrasound sensor matrix.
Abstract: The Twente photoacoustic mammoscope (PAM) uses pulsed light at 1064 nm to excite PA signals. Detection is using a planar 590-element ultrasound (US) sensor matrix. Image reconstruction uses a delay-and-sum beamforming algorithm. Measurements are performed in the forward mode, with mild compression of the breast against the detector with US coupling gel. We consolidate the most important specifications of the system. Furthermore, we discuss in detail the results of imaging two cases of infiltrating ductal carcinoma and one case of a cyst. We critically discuss the features of the present embodiment and present plans for its improvement.
TL;DR: This paper describes the achievements in optical intersatellite communication based on technology developments that started in Europe more than 30 years ago and established an inters satellite link between the near-field infrared experiment and TerraSAR-X satellites already based on the second generation of laser communication technology.
Abstract: This paper describes the achievements in optical intersatellite communication based on technology developments that started in Europe (European Space Agency) more than 30 years ago. In 2001, the world-first optical intersatellite communication link was established (between the SPOT-4 and Advanced Relay and TEchnology MIssion Satellite (ARTEMIS) satellites), proving that optical communication technologies can be reliably mastered in space. In 2006, the Japanese Space Agency (JAXA) demonstrated a bidirectional optical link between its Optical Inter-Orbit Communications Engineering Test Satellite and ARTEMIS, and in 2008, the German Space Agency (DLR) established an intersatellite link between the near-field infrared experiment and TerraSAR-X satellites already based on the second generation of laser communication technology.
TL;DR: The laboratory characterization and in vivo biocompatibility studies support further development and characterization of a fracture healing system based on implantable nested SRR.
Abstract: We designed, fabricated, and characterized metamaterial-based RF-microelectromechanical system (RF-MEMS) strain sensors that incorporate multiple split ring resonators (SRRs) in a compact nested architecture to measure strain telemetrically. We also showed biocompatibility of these strain sensors in an animal model. With these devices, our bioimplantable wireless metamaterial sensors are intended, to enable clinicians, to quantitatively evaluate the progression of long-bone fracture healing by monitoring the strain on the implantable fracture fixation hardware in real time. In operation, the transmission spectrum of the metamaterial sensor attached to the implantable fixture is changed when an external load is applied to the fixture, and from this change, the strain is recorded remotely. By employing telemetric characterizations, we reduced the operating frequency and enhanced the sensitivity of our novel nested SRR architecture compared to the conventional SRR structure. The nested SRR structure exhibited a higher sensitivity of 1.09 kHz/kgf operating at lower frequency compared to the classical SRR that demonstrated a sensitivity of 0.72 kHz/kgf. Using soft tissue medium, we achieved the best sensitivity level of 4.00 kHz/kgf with our nested SRR sensor. Ultimately, the laboratory characterization and in vivo biocompatibility studies support further development and characterization of a fracture healing system based on implantable nested SRR.
TL;DR: In this paper, progress on the gold-nanoparticle-enhanced photothermal therapy is reviewed, and the effects of various parameters on the therapeutic efficiency and mechanisms of gold nanoparticles assisted cancer therapy are discussed.
Abstract: In this paper, progress on the gold-nanoparticle-enhanced photothermal therapy is reviewed. Size- and shape-dependent optical absorption of gold nanoparticles, the effects of various parameters on the therapeutic efficiency, and the mechanisms of gold-nanoparticle-assisted cancer therapy are discussed. Future research directions of gold-nanoparticle-assisted cancer photothermal therapy are also suggested.
TL;DR: In this paper, the authors numerically analyze the characteristics of silicon-based microring modulators consisting of a single-ring resonator and show that cavity dynamics significantly affect the modulation properties.
Abstract: We numerically analyze the characteristics of silicon-based microring modulators consisting of a single-ring resonator. Performance of the devices as digital intensity modulators is examined in terms of extinction ratio, pulsewidth, frequency chirp, spectral broadening, and signal quality. Three types of the modulators built in single-waveguide under-/overcoupling and dual-waveguide configurations are discussed. We show that cavity dynamics significantly affect the modulation properties. Data transmission performance over single-mode fibers is also presented. A silicon microring modulator with negative chirp could achieve 0.8 dB power penalty in 80-km fiber transmission without dispersion compensation.
IBM1
TL;DR: This paper reviews recent progress on CMOS-integrated optical receivers for on-chip interconnects, which have become attractive for achieving communication bandwidth well beyond terabit-per-second with low-power consumption.
Abstract: This paper reviews recent progress on CMOS-integrated optical receivers for on-chip interconnects, which have become attractive for achieving communication bandwidth well beyond terabit-per-second with low-power consumption. The design of optical receivers and the performance metrics required from the photodetector (PD) for a low-power receiver is discussed. The progress in waveguide-integrated germanium PDs is reviewed in depth by exploring various optical/electrical designs, and the associated integration approaches for Ge films and metal contacts. The impact of design and integration on PD performance is evaluated by comparing reported results. Finally, the challenges of monolithic integration of PDs within standard CMOS process are discussed.
TL;DR: In this paper, a mode-evolution-based polarization rotator in silicon waveguide was designed to provide the polarization rotation with polarization extinction ratio of 15 dB, the insertion loss at the transition region was less than 1 dB.
Abstract: A mode-evolution-based polarization rotator in silicon waveguide was designed. The rotator's performance was studied under different launching conditions. The rotator with minimum length of 40 ?m was demonstrated to provide the polarization rotation with polarization extinction ratio of 15 dB. The insertion loss at the transition region was less than 1 dB.