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Showing papers in "IEEE Journal of Selected Topics in Quantum Electronics in 2000"


Journal ArticleDOI
TL;DR: The evolution of the theory of mode-locking over the last three and a half decades is reviewed and some of the salient experiments are discussed in the context of theory as discussed by the authors, with two-cycle pulses of a mode-locked Ti:sapphire laser.
Abstract: The evolution of the theory of mode-locking over the last three and a half decades is reviewed and some of the salient experiments are discussed in the context of the theory. The paper ends with two-cycle pulses of a mode-locked Ti:sapphire laser.

1,227 citations


Journal ArticleDOI
TL;DR: The lithium-niobate external-modulator technology meets the performance and reliability requirements of current 2.5-, 10-Gb/s digital communication systems, as well as CATV analog systems, and multiple high-speed modulation functions have been achieved in a single device.
Abstract: The current status of lithium-niobate external-modulator technology is reviewed with emphasis on design, fabrication, system requirements, performance, and reliability. The technology meets the performance and reliability requirements of current 2.5-, 10-, and 40-Gb/s digital communication systems, as well as CATV analog systems. The current trend in device topology is toward higher data rates and increased levels of integration. In particular, multiple high-speed modulation functions, such as 10-Gb/s return-to-zero pulse generation plus data modulation, have been achieved in a single device.

1,221 citations


Journal ArticleDOI
TL;DR: In this paper, the authors report on advances in polymeric waveguide technologies developed worldwide for the telecom and datacom markets, and describe in detail one such technology developed at AlliedSignal.
Abstract: We report on advances in polymeric waveguide technologies developed worldwide for the telecom and datacom markets, and we describe in detail one such technology developed at AlliedSignal. Optical polymers are versatile materials that can be readily formed into planar single-mode, multimode, and microoptical waveguide structures ranging in dimensions from under a micrometer to several hundred micrometers. These materials can be thermoplastics, thermosets, or photopolymers, and the starting formulations are typically either polymers or oligomers in solution or liquid monomers. Transmission losses in polymers can be minimized, typically by halogenation, with state-of-the-art loss values being about 0.01 dB/cm at 840 nm and about 0.1 dB/cm at 1550 nm. A number of polymers have been shown to exhibit excellent environmental stability and have demonstrated capability in a variety of demanding applications. Waveguides can be formed by direct photolithography, reactive ion etching, laser ablation, molding, or embossing. Well-developed adhesion schemes permit the use of polymers on a wide range of rigid and flexible substrates. Integrated optical devices fabricated to date include numerous passive and active elements that achieve a variety of coupling, routing, filtering, and switching functions.

694 citations


Book ChapterDOI
Arthur Ashkin1
TL;DR: The history of optical trapping and manipulation of small-neutral particles is reviewed in this paper, from the time of its origin in 1970 up to the present, and the unique characteristics of this technique are having a major impact on the many subfields of physics, chemistry, and biology where small particles play a role.
Abstract: Reviews the history of optical trapping and manipulation of small-neutral particles, from the time of its origin in 1970 up to the present. As we shall see, the unique characteristics of this technique are having a major impact on the many subfields of physics, chemistry, and biology where small particles play a role.

626 citations


Journal ArticleDOI
TL;DR: In this article, the progress of the surface emitting laser and the vertical-cavity surface-emitting laser (VCSEL), covering the spectral band from infrared to ultraviolet by featuring its physics, materials, fabrication technology, and performances, such as threshold, output powers, polarizations, linewidth, modulation, reliability, and so on.
Abstract: The surface-emitting laser (SEL) is considered one of the most important devices for optical interconnects and LANs, enabling ultra parallel information transmission in lightwave and computer systems. We introduce its history, fabrication technology, and discuss the advantages. Then, we review the progress of the surface emitting laser and the vertical-cavity surface-emitting laser (VCSEL), covering the spectral band from infrared to ultraviolet by featuring its physics, materials, fabrication technology, and performances, such as threshold, output powers, polarizations, line-width, modulation, reliability, and so on.

619 citations


Journal ArticleDOI
TL;DR: In this paper, the progress from simple gates using cross-gain modulation and four-wave mixing to the integrated interferometric gates using a cross-phase modulation is reviewed, which is very efficient for high-speed signal processing and open up interesting new areas, such as all-optical regeneration and high-time logic functions.
Abstract: Semiconductor optical amplifiers are useful building blocks for all-optical gates as wavelength converters and OTDM demultiplexers. The paper reviews the progress from simple gates using cross-gain modulation and four-wave mixing to the integrated interferometric gates using cross-phase modulation. These gates are very efficient for high-speed signal processing and open up interesting new areas, such as all-optical regeneration and high-speed all-optical logic functions.

520 citations


Journal ArticleDOI
TL;DR: Several key techniques for modeling photonic devices, including several mode-solving techniques, the beam propagation method, the method of lines, and the finite-difference time-domain technique are reviewed.
Abstract: Accurate modeling of photonic devices is essential for the development of new, higher performance optical components required by current and future high-bandwidth communications systems. This paper reviews several key techniques for such modeling, many of which are used in commercial design tools. These include several mode-solving techniques, the beam propagation method, the method of lines, and the finite-difference time-domain technique.

461 citations


Journal ArticleDOI
TL;DR: In this article, the spectroscopic and laser kinetic properties of the trivalent ytterbium ion in various solid-state media are reviewed and compared with four-and quasi-three-level laser architectures, and various architectures suitable for use in high-brightness high-power Yb:YAG lasers are examined.
Abstract: The spectroscopic and laser kinetic properties of the trivalent ytterbium ion in various solid-state media are reviewed. Contrasts between four- and quasi-three-level lasers (e.g., Nd:YAG versus Yb:YAG) are highlighted. Various architectures suitable for use in high-brightness high-power Yb:YAG lasers are examined, and achieved laser performance levels are summarized. The properties of alternative ytterbium-doped laser gain media are reviewed, and early laser results are cited.

425 citations


Journal ArticleDOI
TL;DR: A brief historical summary of the development of the field of optical interconnects to silicon integrated circuits can be found in this paper, where the authors describe the evolution from early optical switching phenomena, through novel semiconductor and quantum well optical and optoelectronic physics and devices, to hybrid integrations of optical and silicon circuits.
Abstract: This paper gives a brief historical summary of the development of the field of optical interconnects to silicon integrated circuits. It starts from roots in early optical switching phenomena, proceeds through novel semiconductor and quantum well optical and optoelectronic physics and devices, first proposals for optical interconnects, and optical computing and photonic switching demonstrators, to hybrid integrations of optoelectronic and silicon circuits that may solve basic scaling and other problems for interconnections in future information processing and switching machines.

365 citations


Journal ArticleDOI
TL;DR: The focus shifts to widely tunable diode lasers, which would appear to be key enablers for future dense wavelength-division multiplexing and optical switching and networking systems.
Abstract: After over two decades of exploration, tunable diode lasers are beginning to find significant applications, driven largely by the huge demand for bandwidth that is guiding many developments in the optical fiber communication business today. In the paper, some of the history and key developments that have led to the technologies available today are reviewed from the perspective of the author. After discussion of some of the early work, the focus shifts to widely tunable diode lasers, which would appear to be key enablers for future dense wavelength-division multiplexing and optical switching and networking systems. The distinguishing characteristics of the current technological alternatives are summarized.

344 citations


Journal Article
TL;DR: The author summarizes some of the early breakthroughs in wavelength engineering of VCSELs and then concentrates on the designs and properties of micromechanical tunable V CSEL.
Abstract: Vertical-cavity surface-emitting lasers (VCSELs) are now key optical sources in optical communications. Their main application is currently in local area networks using multimode optical fibers. VCSELs are also being rapidly commercialized for single-mode fiber metropolitan area and wide area network applications. The advantages of VCSEL include simpler fiber coupling, easier packaging and testing, and the ability to be fabricated in arrays. In addition, VCSELs have an inherent single-wavelength structure that is well suited for wavelength engineering. All these advantages promise to lead to cost-effective wavelength-tunable lasers, which are essential for the future intelligent, all-optical networks. The author reviews the advances on wavelength-tunable VCSELs. She summarizes some of the early breakthroughs in wavelength engineering of VCSELs and then concentrates on the designs and properties of micromechanical tunable VCSEL.

Journal ArticleDOI
C. Stewen1, K. Contag, M. Larionov, A. Giesen, H Hugel 
TL;DR: In this paper, the authors presented an optimal laser design for the operation of a quasi-three-level laser active medium in the high power regime with high optical efficiency, and showed that operation with an output power up to 1 kW with an optical efficiency of 50% and more is possible at room temperature utilizing 16 absorption passes.
Abstract: The thin disc laser is presented as an optimal laser design for the operation of a quasi-three-level laser active medium in the high power regime with high optical efficiency. Numerical calculations of the laser output power show that operation with an output power up to 1 kW with an optical efficiency of 50% and more is possible at room temperature utilizing 16 absorption passes. Scaling of the output power can be realized by scaling the pumped area using one or more discs. The experimental investigations yield a maximum output power of 647 W at 51% optical efficiency for one crystal and of 1070 W with 48% optical efficiency for four crystals at a temperature of the cooling water of 15/spl deg/C.

Journal ArticleDOI
Elsa Garmire1
TL;DR: A review of nonlinear optics in semiconductors can be found in this article, where the focus is on nonlinear absorption and the refractive index that arises from the photo-induced excitation of free carriers.
Abstract: Semiconductors provide some of the most promising materials for nonlinear optics, because of large resonant nonlinearities, control of recombination time (from milliseconds to femtoseconds), well-developed fabrication technologies, and compatibility with other optoelectronic devices. The paper reviews some of the concepts and results that have come from the study of nonlinear optics in semiconductors. The emphasis is on nonlinear absorption and the refractive index that arises from the photo-induced excitation of free carriers. Mechanisms described include state-filling, carrier transport, and photorefractivity. Devices include optical bistability, reflective asymmetric Fabry-Perot all-optical absorptive switches, optically addressed spatial light modulators, and real-time holography. The paper's approach is to provide a basic engineering understanding of the principles, some of the historical details, and a snapshot of the state of the field today.

Journal ArticleDOI
TL;DR: In this article, an electrostatically driven silicon micro scanning mirror (MSM) for one-dimensional and two-dimensional deflection of light is presented, where a special configuration of the driving electrodes allows the use of small electrode gaps without restricting the plate geometrically.
Abstract: An electrostatically driven silicon micro scanning mirror (MSM) for one-dimensional (1-D) and two-dimensional (2-D) deflection of light is presented. A special configuration of the driving electrodes allows the use of small electrode gaps without restricting the deflection of the plate geometrically. In this paper, the starting of the oscillation and the operation of the scanner is discussed. Experimental results show that scan angles of up to 60/spl deg/ can be achieved at a driving voltage of only 20 V. The 2-D deflection of a laser beam is obtained by a gimbal mounting of the mirror plate. For the fabrication of the devices, SOI-wafers are used as the base material. The mechanical structures are defined by a deep silicon etch. For the electrical isolation of areas on the movable frame, polysilicon-filled trenches are used. The mechanical stability of the scanners is tested. The devices resist shocks of more than 1000 g and show no change of the resonance frequency even after long run tests of 7/spl times/10/sup 9/ periods.

Journal ArticleDOI
TL;DR: In this paper, a diode end-pumped Tm:LiYF/sub 4/ (Tm:YLF) laser was used to achieve high power (>36 W) with beam propagation factor M/sup 2/spl sim/2 in a dioder end-Pumped T m:Li YF/Sub 4/Tm-YLF laser generating output near the 1.91-/spl mu/m region.
Abstract: We report high power (>36 W) with beam propagation factor M/sup 2//spl sim/2 in a diode end-pumped Tm:LiYF/sub 4/ (Tm:YLF) laser generating output near the 1.91-/spl mu/m region. Using the 1.91-/spl mu/m emission and high brightness achieved with the Tm:YLF laser we resonantly end-pump the Holmium /sup 5/I/sub 7/ manifold in Ho:YAG and demonstrate /spl sim/19 W of continuous-wave (CW) output. The diode-to-Holmium optical to-optical conversion efficiency achieved is /spl sim/18%. Using a CW pumped and repetitively Q-switched configuration, the Tm:YLF pumped Ho:YAG laser achieves >16 W of output power with an M/sup 2//spl sim/1.48 at 15 kHz. A Q-switched frequency range of 9 to >50 kHz is also achieved.

Journal ArticleDOI
TL;DR: The key technologies, including ultrafast pulse generation, all-optical multiplexing/demultiplexing, and optical timing extraction techniques, are described, together with state-of-the-art performances and future prospects.
Abstract: Recent progress toward multiterabit/s optical transmission systems employing all-optical ultrafast signal-processing technologies is described. Focus is placed on optical time-division multiplexing (OTDM), as well as optical time- and wavelength-division multiplexing (OTDM/WDM) technologies leading to multiterabit/s transmission capacity. The key technologies, including ultrafast pulse generation, all-optical multiplexing/demultiplexing, and optical timing extraction techniques, are also described, together with state-of-the-art performances and future prospects.

Journal ArticleDOI
TL;DR: In this paper, a self-organized growth of QD's allowed the fabrication of dense arrays of coherent islands, uniform in shape and size, and, simultaneously, free from undesirable defects.
Abstract: Quantum-dot (QD) heterostructures are nanoscale coherent insertions of narrow-gap material in a single-crystalline matrix. These tiny structures provide unique opportunities to modify and extend all basic principles of heterostructure lasers and advance their applications. Despite early predictions, fabrication of QD heterostructure (QDHS) lasers appeared to be a much more challenging task, as compared to quantum well (QW) devices. The breakthrough occurred when techniques for self-organized growth of QD's allowed the fabrication of dense arrays of coherent islands, uniform in shape and size, and, simultaneously, free from undesirable defects. Recently, the figure of merit of QDHS lasers surpasses some of the key characteristics of QW devices in some of the most important applications.

Journal ArticleDOI
TL;DR: In this paper, a distributed feedback (DFB) geometry was used to achieve state-of-the-art performance in the mid-infrared range from 4 to 20 µm by using the thickness of the quantum wells in the active region.
Abstract: Recent advances and new directions in quantum cascade (QC) lasers are discussed. Invented in 1994 following many years of research on band-structure engineered semiconductors and devices grown by molecular beam epitaxy, this fundamentally new laser has rapidly advanced to a leading position among midinfrared semiconductor lasers in terms of wavelength agility as well as power and temperature performance. Because of the cascaded structure, QC lasers have a slope efficiency proportional to the number of stages. Devices with 100 stages having a record peak power of 0.6 W at room temperature are reported. QC lasers in the AlInAs-GaInAs lattice matched to InP material system can now be designed to emit in the whole midinfrared range from 4 to 20 /spl mu/m by appropriately choosing the thickness of the quantum wells in the active region. Using strained AlInAs-GaInAs, wavelengths as short as 3.4 /spl mu/m have been produced. New results on QC lasers emitting at 19 /spl mu/m, the longest ever realized in a III-V semiconductor laser, are reported. These devices use innovative plasmon waveguides to greatly enhance the mode confinement factor, thereby reducing the thickness of the epitaxial material. By use of a distributed feedback (DFB) geometry, QC lasers show single-mode emission with a 30-dB side-mode suppression ratio. Broad continuous single-mode tuning by either temperature or current has been demonstrated in these DFB QC lasers at wavelengths in two atmospheric windows (3-5 and 8-13 /spl mu/m), with continuous-wave linewidths <1 MHz when free running and /spl sim/10 KHz with suitable locking to the side of a molecular transition. These devices have been used in a number of chemical sensing and spectroscopic applications, demonstrating the capability of detecting parts per billion in volume of several trace gases. Sophisticated band-structure engineering has allowed the design and demonstration of bidirectional lasers. These devices emit different wavelengths for opposite bias polarities. The last section of the paper deals with the high-speed operation of QC lasers. Gain switching with pulse widths /spl sim/50 ps and active modelocking with a few picosecond-long pulses have been demonstrated. Finally, a new type of passive modelocking has been demonstrated in QC lasers, which relies on the giant and ultrafast optical Kerr effect of intersubband transitions.

Journal ArticleDOI
TL;DR: In this paper, the authors developed ultrashort pulse generation by the electrooptic modulation method, where continuous-wave laser light of any wavelength can be converted to trains of ultra-short optical pulses with a variable and high repetition frequency by means of an electro-optic phase modulator, and an optical group-delay-dispersion circuit or an optical synthesizer for the compression of the chirped light.
Abstract: We have developed ultrashort pulse generation by the electrooptic modulation method, where continuous-wave laser light of any wavelength can be converted to trains of ultrashort optical pulses with a variable and high repetition frequency by means of an electrooptic phase modulator for the generation of deeply chirped light, and an optical group-delay-dispersion circuit or an optical synthesizer for the compression of the chirped light. Adopting the technologies of domain inversion and guided-wave optics to this electrooptic modulation method, it will be possible to realize integrated ultrashort optical pulse generators.

Journal ArticleDOI
TL;DR: In this paper, the spectral hole-burning and carrier heating were investigated in detail in a set of InAs-InGaAs-GaAs quantum-dot (QD) amplifiers with femtosecond resolution.
Abstract: The ultrafast gain and index dynamics in a set of InAs-InGaAs-GaAs quantum-dot (QD) amplifiers are measured at room temperature with femtosecond resolution. The role of spectral hole-burning (SHB) and carrier heating (CH) in the recovery of gain compression is investigated in detail. An ultrafast recovery of the spectral hole within /spl sim/100 fs is measured, comparable to bulk and quantum-well amplifiers, which is contradicting a carrier relaxation bottleneck in electrically pumped QD devices. The CH dynamics in the QD is quantitatively compared with results on an InGaAsP bulk amplifier. Reduced CH for both gain and refractive index dynamics of the QD devices is found, which is a promising prerequisite for high-speed applications. This reduction is attributed to reduced free-carrier absorption-induced heating caused by the small carrier density necessary to provide amplification in these low-dimensional systems.

Journal ArticleDOI
TL;DR: In this paper, the combined effects of polarization-mode dispersion (PMD) and polarization dependent losses (PDL) in optical fiber networks were investigated and it was shown that the combination of PMD and PDL may lead to anomalous dispersion, which is not correctly described by a direct application of the Jones matrix eigenanalysis (JME) method.
Abstract: We review the formalism required to investigate the combined effects of polarization-mode dispersion (PMD) and polarization dependent losses (PDL) in optical fiber networks. The combination of PMD and PDL may lead to anomalous dispersion, which is not correctly described by a direct application of the Jones matrix eigenanalysis (JME) method. This calls for a careful assessment of PMD measurement methods in the presence of PDL. We also present a theoretical analysis of distortions in analog transmissions, and computer simulations of digital transmissions. These show that distributed PDL increases the power penalty of the transmission more than lumped PDL at the end of the channel.

Journal ArticleDOI
TL;DR: In this paper, an outline of planar lightwave circuits (PLCs) focusing on passive devices such as arrayed waveguide grating multiplexers is presented. But the authors do not discuss the role of PLCs in both optical dense wavelength-division multiplexing networks and optical access networks.
Abstract: Silica-based planar lightwave circuits (PLCs) are playing key roles in both optical dense wavelength-division multiplexing networks and optical access networks. This paper provides an outline of PLC technology focusing on passive devices such as arrayed waveguide grating multiplexers.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the historical evolution of spatial solitons from speculative creatures to one of the most fascinating features optics has to offer, and describe the history and evolution of the field of soliton research.
Abstract: Optical spatial solitons are self-trapped optical beams that exist by virtue of the balance between diffraction and nonlinearity. They propagate and interact with one another while displaying properties that are normally associated with real particles. Solitons, in general, manifest themselves in a large variety of wave/particle systems in nature: practically in any system that possesses both dispersion (in time or space) and nonlinearity. Solitons have been identified in optics, plasmas, fluids, condensed matter, particle physics, and astrophysics. Yet over the past decade, the forefront of soliton research has shifted to optics. In the paper, we describe the historical evolution of spatial solitons from speculative creatures to one of the most fascinating features optics has to offer.

Journal ArticleDOI
TL;DR: The critical technology and architecture issues to be addressed for the realization of wide-area space data networks of the future are discussed, and examples of high level designs are presented.
Abstract: Optical space communications is on the verge of becoming a reality. It will be a key building block for wide-area space data networks of the future. We discuss the critical technology and architecture issues to be addressed for the realization of these systems, and present examples of high level designs. Design methodologies treating these as complex engineering systems, and the technique to breakdown the systems into interacting but logically separate subsystems for design and analysis, are suggested. Fundamental limits of performance and avenues for promising future research and development are given.

Journal ArticleDOI
TL;DR: In this paper, the authors present the latest developments of diode-pumped Ti,Er:LiNbO/sub 3/ waveguide lasers emitting at wavelengths around 1.5 /spl mu/m.
Abstract: This paper reviews the latest developments of diode-pumped Ti,Er:LiNbO/sub 3/ waveguide lasers emitting at wavelengths around 1.5 /spl mu/m. In particular, harmonically mode-locked lasers, Q-switched lasers, distributed Bragg reflector (DBR)-lasers, and self-frequency doubling lasers are discussed in detail. Supermode stabilized mode-locked lasers have been realized using a coupled cavity concept; a side mode suppression ratio of 55 dB has been achieved at 10-GHz pulse repetition rate with almost transform limited pulses. Q-switched lasers with a high extinction ratio (>25 dB) intracavity electrooptic switch emitted pulses with a peak power level up to 2.5 kW and a pulsewidth down to 2.1 ns at 1-kHz repetition frequency. Numerical simulations for both lasers are in a good, almost quantitative agreement with experimental results. A DBR-laser of narrow linewidth (/spl ap/3 GHz) with a permanent (fixed) photorefractive grating and 5 mW output power has been realized. Self frequency doubling lasers have been fabricated with a periodic microdomain structure inside an Er-doped laser cavity; simultaneous emission at the fundamental wavelength, 1531 nm, and at the second harmonic wavelength, 765 nm, has been obtained.

Journal ArticleDOI
TL;DR: In this article, the current state-of-the-art of colloidal II-VI nanocrystal formation using the aqueous/thiol synthesis route is described, and the purpose of the work is to provide a range of infrared (IR)-emitting materials with high quantum efficiency (QE) as potential gain media for future ultrawideband optical amplifiers for high-capacity wavelength division multiplexing (WDM) telecommunications systems.
Abstract: The current state-of-the-art of colloidal II-VI nanocrystal formation using the aqueous/thiol synthesis route is described. Work on single component and heterostructures and mixed compound quantum dots is discussed. The purpose of the work is to provide a range of infrared (IR)-emitting materials with high quantum efficiency (QE) as potential gain media for future ultrawideband optical amplifiers for high-capacity wavelength-division multiplexing (WDM) telecommunications systems. Physical and chemical factors influencing particle sizes are described.

Journal ArticleDOI
TL;DR: A review of recent results on medium-power CW Raman fiber lasers pumped by laser diodes is presented in this article, where most attention is given to Raman lasers based on phosphosilicate fibers.
Abstract: A review of recent results on medium-power CW Raman fiber lasers pumped by laser diodes is presented. Most attention is given to Raman lasers based on phosphosilicate fibers, the latter providing a number of advantages compared to commonly used germanosilicate fibers.

Journal ArticleDOI
TL;DR: In this article, the state-of-the-art in the use of quantum-dot nanostructures in infrared detectors is reviewed, and the progress, challenges, and projections for continued development of normal-incidence intersublevel detectors operating in the spectral region between 6 and 20 /spl mu/m.
Abstract: Semiconductor quantum-dot nanostructures are interesting objects for fundamental as well as practical reasons. Fundamentally, they can form the basis of systems in which to study the quantum mechanics of electrons confined in zero-dimensional (0-D) space. In practice, the dots can be embedded in the active regions of a new class of electronic and optoelectronic devices with novel functionalities. This paper reviews the state-of-the-art in the use of these objects in infrared detectors. It describes the progress, challenges, and projections for continued development of normal-incidence intersublevel detectors operating in the spectral region between 6 and 20 /spl mu/m.

Journal ArticleDOI
TL;DR: An overview of recent progress in PLC hybrid integration technology including optoelectronic semiconductor devices for the hybrid integration, various devices for wavelength-division multiplexing, and all-optical time-division multixing is presented in this paper.
Abstract: Silica-based planar lightwave circuit (PLC) hybrid integration is a promising way to provide highly functional photonic components. This paper is an overview of recent progress in PLC hybrid integration technology including optoelectronic semiconductor devices for the hybrid integration, various devices for wavelength-division multiplexing, and all-optical time-division multiplexing.

Journal ArticleDOI
TL;DR: In this paper, an overview of an experimental search for an ultrawide-band transmission channel with low dispersion and loss is presented, together with phase-coherent Cherenkov radiation in the form of an electromagnetic shock wave from these propagating electrical pulses.
Abstract: An overview is presented of an experimental search for an ultrawide-band transmission channel with low dispersion and loss. Such a terahertz (THz) interconnect will soon be required by the insatiable demand for higher speed devices and wider bandwidth communication. Starting with the early optoelectronic generation and detection of single-mode, subpicosecond electrical pulses on coplanar transmission lines, their complete characterization by THz time-domain spectroscopy (THz-TDS) is described. The consequent discovery of phase-coherent Cherenkov radiation in the form of an electromagnetic shock wave from these propagating electrical pulses is discussed together with its dominant role in the large measured propagation loss of these pulses. Various techniques to reduce this radiation are presented. The importance of dielectric materials characterization is explained and illustrated by THz-TDS measurements of high T/sub c/ substrates. Newly obtained THz waveguide results are presented and compared to the performance of coplanar transmission lines.