A5016050548- Photonic and Optical Devices
- Advanced Photonic Communication Systems
- Semiconductor Lasers and Optical Devices
- Optical Network Technologies
- Advanced Fiber Laser Technologies
- Semiconductor Quantum Structures and Devices
- Terahertz technology and applications
- Spectroscopy and Laser Applications
- Advanced Fiber Optic Sensors
- Advanced Frequency and Time Standards
- Superconducting and THz Device Technology
- Photonic Crystals and Applications
- Advanced Optical Network Technologies
- Solid State Laser Technologies
- Radio Frequency Integrated Circuit Design
- Semiconductor materials and devices
- Microwave Engineering and Waveguides
- Photonic Crystal and Fiber Optics
- Silicon Nanostructures and Photoluminescence
- Laser-Matter Interactions and Applications
- Millimeter-Wave Propagation and Modeling
- Network Time Synchronization Technologies
- Semiconductor materials and interfaces
- Nanowire Synthesis and Applications
- Plasmonic and Surface Plasmon Research
University College London
2016-2025
University of Duisburg-Essen
2024
Deutsche Forschungsgemeinschaft
2024
Conference Board
2024
Tokyo Institute of Technology
2024
University of London
2024
University of Sheffield
1992-2019
Beijing University of Technology
2019
Laboratoire de physique des lasers
2018
Université Sorbonne Paris Nord
2018
Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz–30 THz) have developed rapidly over the last 30 years. For most of 20th Century, radiation, then referred to as sub-millimeter wave or far-infrared was mainly utilized by astronomers some spectroscopists. Following development laser time-domain spectroscopy in 1980s 1990s field THz science technology expanded rapidly, extent that it now touches many areas from fundamental 'real world' applications....
The low-loss wide bandwidth capability of opto-electronic systems makes them attractive for the transmission and processing microwave signals, while development high-capacity optical communication has required use techniques in transmitters receivers. These two strands have led to research area photonics. This paper reviews status photonic devices, describes their applications, suggests some likely areas future
The low-loss wide-bandwidth capability of optoelectronic systems makes them attractive for the transmission and processing microwave signals, while development high-capacity optical communication has required use techniques in transmitters receivers. These two strands have led to research area photonics. This paper describes photonic devices, their applications, suggests likely areas future development.
Optical fibre transmission has enabled greatly increased rates with 10 Gb/s common in local area networks. End users find wireless access highly convenient for mobile communication. However, limited spectrum availability at microwave frequencies results per-user to much lower values, e.g., 500 Mb/s 5-GHz band IEEE 802.11ac. Extending the high data-rate capacity of optical fiber devices requires carrier frequencies. This paper will describe how photonic techniques can enable ultrahigh data...
We report the first operation of an electrically pumped 1.3-μm InAs/GaAs quantum-dot laser epitaxially grown on a Si (100) substrate. The structure was directly substrate by molecular beam epitaxy. Lasing at 1.302 μm has been demonstrated with threshold current density 725 A/cm2 and output power ~26 mW for broad-area lasers as-cleaved facets room temperature. These results are attributable to optimized growth temperature initial GaAs nucleation layer.
Nanometre-scale semiconductor devices have been envisioned as next-generation technologies with high integration and functionality. Quantum dots, or the so-called 'artificial atoms', exhibit unique properties due to their quantum confinement in all 3D. These brought light great potential of dots optoelectronic applications. Numerous efforts worldwide devoted these promising nanomaterials for devices, such lasers, photodetectors, amplifiers, solar cells, emphasis on improving performance...
This tutorial review paper deals with various methods for solving a basic problem of wideband phased arrays, i.e. beam squinting, using optical technologies. The squinting in arrays is analyzed and the concept true-time delay introduced. advantages realizing variable lines by rather than microwave means are reviewed, together principles operation. Among techniques described switched-path length lines, fiber stretchers, tunable lasers highly dispersive fiber, coherent incorporating delay....
The use of optically controlled devices to perform a range circuit functions is reviewed. optical control amplifier performance discussed. two- and three-terminal oscillators pumped mixers Among the active treated are Gunn IMPATT oscillators; MESFET HEMT amplifiers, oscillators, mixtures; diode mixers. Future directions for research in this area discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
The requirement for narrow linewidth lasers or short-loop propagation delay makes the realization of optical phase-lock loops using semiconductor difficult. Although injection locking can provide low phase error variance wide lasers, range is restricted by stability considerations. Theoretical and experimental results a system which combines both techniques so as to overcome these limitations, loop (OIPLL), are reported. Phase values 0.006 rad/sup 2/ (500 MHz bandwidth) ranges exceeding 26...
The first experimental demonstration is reported of a heterodyne optical phase-lock loop (OPLL) using semiconductor lasers without external cavities or other linewidth narrowing methods. For total propagation delay 3 ns and filter bandwidth 700 MHz, phase error variance 1.02 rad2 was achieved in 500 MHz measurement bandwidth.
We report the first room-temperature continuous-wave operation of III-V quantum-dot laser diodes monolithically grown on a Si substrate. Long-wavelength InAs/GaAs structures were fabricated Ge-on-Si substrates. Room-temperature lasing at wavelength 1.28 μm has been achieved with threshold current densities 163 A/cm(2) and 64.3 under pulsed conditions for ridge-waveguide lasers as cleaved facets, respectively. The value represents lowest density any kind to date.
We report on advanced millimeter-wave (mm-wave) photonic components for broadband radio transmission. have developed self-pulsating 60-GHz range quantum-dash Fabry-Perot mode-locked laser diodes (MLLD) passive, i.e., unlocked, mm-wave generation with comparably low-phase noise level of -76 dBc/Hz @ 100-kHz offset from a 58.8-GHz carrier. further high-frequency 1.55-μm waveguide photodiodes (PD) partially p-doped absorber operation (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML"...
We compare InAlAs/GaAs and InGaAs/GaAs strained-layer superlattices (SLSs) as dislocation filter layers for 1.3-μm InAs/GaAs quantum-dot laser structures directly grown on Si substrates. SLSs are found to be more effective than in blocking the propagation of threading dislocations generated at interface between GaAs buffer layer substrate. Room-temperature lasing ~1.27 μm with a threshold current density 194 A/cm(2) output power ~77 mW has been demonstrated broad-area lasers substrates using layers.
We report on the first electrically pumped continuous-wave (cw) InAs/GaAs quantum dot (QD) lasers monolithically grown on-axis Si (001) substrates without any intermediate buffer layers. A 400 nm antiphase boundary (APB) free epitaxial GaAs film with a small root-mean-square (RMS) surface roughness of 0.86 was deposited 300 mm standard industry-compatible substrate by metal-organic chemical vapor deposition (MOCVD). The QD laser structure then this APB-free GaAs/Si virtual molecular beam...
The realization of semiconductor lasers on Si substrates will enable the fabrication complex optoelectronic circuits. This permit creation long-dreamed chip-to-chip and system-to-system optical interconnects. paper reports recent developments in our work InAs/GaAs quantum-dot (QD) monolithically grown Si, Ge, Ge-on-Si (Ge/Si) substrates. A thin AlAs nucleation layer (NL) was first investigated for growth QDs NL enables more defects to be confined interface between GaAs epitaxial substrate,...
This paper describes the advantages that introduction of photonic integration technologies can bring to development photonic-enabled wireless communications systems operating in millimeter wave frequency range. We present two approaches for dual wavelength sources heterodyne-based generation realized using active/passive technology. One approach integrates monolithically distributed feedback semiconductor lasers along with optical amplifiers, combiners, electro-optic modulators and broad...
We propose and experimentally demonstrate a photonic multichannel terahertz (THz) wireless system with up to four optical subcarriers total capacity as high 100 Gb/s by employing an externally injected gain-switched laser comb source. Highly coherent multiple carriers different spacing are produced using the gain switching technique. Single- Terahertz signals generated heterodyne mixing of modulated single or one unmodulated tone spaced about 200 GHz. The frequency stability phase noise...
A series of AlxGa(1−x)As ternary alloys were grown by molecular beam epitaxy (MBE) at the technologically relevant composition range, x &lt; 0.45, and characterized using spectroscopic ellipsometry to provide accurate refractive index values in wavelength region below bandgap. Particular attention is given O-band C-band telecommunication wavelengths around 1.3 µm 1.55 µm, as well 825 nm. MBE gave a very high accuracy for layer thicknesses, alloys’ precise compositions bandgap confirmed...
In this paper, we present the first fully packaged semiconductor laser optical phase-locked loop (OPLL) microwave photonic transmitter. The transmitter is based on lasers that are directly phase locked without use of any other noise-reduction mechanisms. transmitter, have a free-running summed linewidth 6 MHz and OPLL has feedback bandwidth 70 MHz. A state-of-the-art performance obtained, with total phase-error variance 0.05 rad/sup 2/ (1-GHz bandwidth) carrier 7/spl times/10/sup -4/ in...
The design, experimental evaluation and performance of a Traveling-Wave Uni-Traveling Carrier photodiode for Terahertz generation are described its advantages in terms frequency response demonstrated. device delivered 148 microW at 457 GHz, 24 914 GHz when integrated with resonant antennas 105 255 30 408 16 510 10 612 GHz. Record levels figure merit (PTHz/Popt2 W(-1)) were achieved ranging from 1 W(-1) 110 to 0.0024