A5090496100- Advanced Photonic Communication Systems
- Photonic and Optical Devices
- Optical Network Technologies
- Semiconductor Lasers and Optical Devices
- Semiconductor Quantum Structures and Devices
- Advanced Fiber Laser Technologies
- Semiconductor materials and devices
- Advanced Fiber Optic Sensors
- Advanced Optical Network Technologies
- Terahertz technology and applications
- Radio Frequency Integrated Circuit Design
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor materials and interfaces
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Semiconductor Detectors and Materials
- GaN-based semiconductor devices and materials
- Advanced Optical Sensing Technologies
- Microwave Engineering and Waveguides
- Software-Defined Networks and 5G
- Photonic Crystal and Fiber Optics
- Near-Field Optical Microscopy
- Optical Coatings and Gratings
- Cloud Computing and Resource Management
- Pulsed Power Technology Applications
- Gyrotron and Vacuum Electronics Research
Ciena (United States)
2003-2024
Utility Development (United States)
2020
United States Naval Research Laboratory
1993-2005
University of Michigan
1989-2005
Optical Sciences (United States)
1992-2002
Optica
2002
Signal Processing (United States)
2002
Drexel University
1997
National Institute of Standards and Technology
1997
Naval Research Laboratory Optical Sciences Division
1995
Epitaxial GaAs grown by molecular beam epitaxy (MBE) at low substrate temperatures is observed to have a significantly shorter carrier lifetime than normal temperatures. Using femtosecond time-resolved-reflectance techniques, sub-picosecond (<0.4 ps) has been measured for MBE ∼200°C and annealed 600 °C. With the same material as photoconductive switch we electrical pulses with full-width half-maximum of 0.6 ps using technique electro-optic sampling. Good responsivity observed,...
A novel material deposited by molecular beam epitaxy at low substrate temperatures using Ga and As4 fluxes has been used as the active layer for a high-speed photoconductive optoelectronic switch. The performance of was assessed fabricating two devices: an Auston switch photoconductive-gap with coplanar transmission line. In line configuration, speed response is 1.6 ps (full width half maximum) 10 to 100 times greater than that conventional switches. Since compatible GaAs discrete device...
Experimental verification of analytic formulas for the dispersion and attenuation electrical transient signals propagating on coplanar transmission lines is presented. The done in frequency domain over a terahertz range although experiments are time domain. obtained from fits to full-wave analysis results. It quantitatively verified that steady-state solutions can be directly applied time-domain propagation experiments. Subpicosecond pulses an external electrooptic sampling technique used...
Experimental results for an optical-control technique implementing a true time-delay function array antennas are reported. A microwave signal is transmitted on wavelength-tunable optical carrier through fiber-optic prism-a set of nominally equal-delay fibers with differing net dispersion-to photodetectors that feed each antenna element. The relative interelement (beam angle) adjustment accomplished by tuning the wavelength. Measured patterns two-element clearly demonstrate beam steering and...
A true time-delay beamformer based on a fiber-optic dispersive prism is developed and characterized. The used to control an ultrawideband time-steered array antenna, which significant improvement over inherently narrowband phased-array antennas. transmitter antenna consists of eight broadband spiral elements in sparsely-populated array. In transmit mode the bandwidth microwave-component limited 2-18 GHz. shows unprecedented performance with >100/spl deg/ azimuth steering no observed squint...
Saturation of photodetectors is measured in the time domain using optical pulses different duration and frequency amplitude-modulated carriers. In domain, saturation characterized by a reduction peak photocurrent growth pulse tail indicating that significant carrier velocity occurring as opposing space-charge field persists. response to sinusoidal signal. The time-domain measurements are shown result substantially larger 1-dB compression currents than frequency-domain for same photodiode....
We develop and demonstrate a technique for implementing wide-band optical single-sideband suppressed-carrier modulator. The relies on dual-electrode traveling wave modulator sideband suppression Sagnac fiber-loop interferometer carrier suppression. implementation uses all commercially available components demonstrates >40 dB suppression, as much 60 unwanted signal rejection across 6-20 GHz microwave frequency range. is used to broad-band spectral shifting- inversion the 3-18
Recent advances in state-of-the-art optoelectronic techniques applied to areas pertinent transistor small-signal and large-signal characterization are discussed. The aspects of for electrical signal measurement, generation, transmission studied. On the basis these results, a digital-switching methodology is developed. This used estimate parameters high-electron-mobility obtain characteristics this device on picosecond time scale. measurements compared SPICE-based time-domain model....
We demonstrate a high-resolution technique to measure the optical magnitude and phase responses of fiber gratings. The employs single-sideband modulation an source has spectral resolution in hertz regime. is demonstrated by measurement ripples unapodized apodized chirped gratings as well transmission spectrum pi-phase-shifted grating. Although it on gratings, applicable any device.
The authors demonstrate a photonic analogue-digital converter architecture based on temporal-spectral mapping. Linearily chirped optical pulses form quasi-continuous carrier modulated by the analogue RF signal. signal is separated into several distinct wavelength channels for parallel demodulation and quantisation. Measurements performed 70 ps electrical signals indicate six bit resolution.
A GaAs material grown by molecular beam epitaxy at a low substrate temperature was used to fabricate photoconductor switch that produces 6-V picosecond electrical pulses. The pulses were produced on microwave coplanar-strip transmission line lithographically patterned the low-temperature (LT) GaAs. 150-fs laser pulse generate carriers in LT gap between metal strips, partially shorting high DC voltage placed across lines. magnitude of obtained is believed be limited power and not properties...
The architecture and component technology of a low power, high capacity, short reach optical interconnect are detailed. Measurements from high-performance 300 mm silicon photonics components that comprise the system shown, along with quantum-dot mode-locked laser 20-channel comb source free space wall plug efficiencies up to 17%, advanced packaging techniques for 3D photonic-electronic integration, schematics integrated electronics control photonic circuits. Techniques operating such in...
The accuracy and invasiveness of various external LiTaO/sub 3/ electrooptic probe (EEP) geometries are investigated experimentally. EEPs studied used for microwave coplanar transmission-line measurements. It is shown that commonly employed EEP can cause substantial inaccuracies in their measurements these be related to specific geometric parameters. major distortions pulse was found attributable electromagnetic radiation coupling into the crystal resonating between top bottom interfaces....
We report the development and demonstration of first true time-delay (TTD) fiber-optic beamformer for ultrawideband antenna receive operation. The is based on a dispersive-fiber prism configuration that properly time delays signals originating at each receiving element coherent combining in microwave domain. time-steered consists eight spiral elements arranged into one-dimensional (l-D) sparsely populated array. array shows an instantaneous bandwidth 6-18 GHz, limited by available matched...
A wide-band fiber-optic true-time-delay array receiver capable of receiving multiple independent beams simultaneously is demonstrated for the first time.The based on a dispersive prism technique and exhibits squint-free 660 azimuthal steering two simultaneous with no observable beam squint over microwave component-limited bandwidth 6-18 GHz.
We investigate the attenuation and phase velocity characteristics of coplanar strip (CPS) transmission lines designed for high-speed, low-loss propagation at sub-THz frequencies. Photoconductor switches driven by femtosecond optical pulses were used to generate propagating picosecond electrical transients. External electrooptic sampling was measure time-domain impulse-response with subpicosecond time resolution. The finite-difference transmission-line-matrix (FD-TLM) numerical method model...
We analyze the blocking performance of spectrum efficient super-channels in dynamic flexible grid networks. Results demonstrate that increased spectral efficiency and super-channel assignment do translate into network gains.
We demonstrate a phased-array antenna controlled by fiber-optic beamformer in true time-delayed transmit mode and phase-delayed receive mode. The wavelength-tunable optical carrier propagating high-dispersion fiber realizes time-delay, with the steering direction set single voltage controlling wavelength. linear is sparsely-populated array eight broadband spiral elements. transmitter operates 2-18 GHz frequency range over /spl plusmn/50/spl deg/ azimuth steering, receiver 6-16 plusmn/35/spl...
The authors have developed a novel, simple chirped-grating based beamformer for time-steered array antennas. is on commercially available chirped fibre gratings and optical circulators has measured bandwidth of over 18 GHz. first-ever demonstration achieves quasi-continuous 1D steering 45°.
We report a first demonstration of fiber-optic beamformer for independent two-dimensional (2-D) true time-delay steering transmitter array. The is based on simple dispersive prism optical delay approach, with separate azimuth and elevation control stages. stage includes an amount dispersion in each link proportional to the corresponding column position microwave signals, properly time-delayed steering, are amplified serve as inputs identical prisms feeding elements column. stages include row...
We report an experimental demonstration of a photonic microwave shifter using highly chirped mode-locked fiber laser. The system is based on dispersive compression or expansion optical pulses that are amplitude modulated by the signal. Using this technique, we demonstrated frequency shifting signal from 10 GHz down to 5 and up 25 GHz.
We have developed and studied what we believe is the first fiber laser operating in a single polarization at 1550 nm with PM output capable of wavelength tuning over 20-nm bandwidth less than 50 μs. The fast speed achieved by incorporating an acousto-optic tunable filter into laser. same used optoelectronic feedback loop to suppress relaxation oscillations induced transitions.