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Using the Eigen-mode approach we analyze the imaging performance of multilayer hyperbolic metamaterials and show that resolution decreases with the number of layers and amount of metal loss.
We have developed a time domain model confirming that the most efficient mode operation of a free running QCL is a pseudo-random frequency modulated mode with constant intensity.
We demonstrate a tunable optical time delay line based on Si3N4 ring resonators. A continuously tunable 1.4 ns optical delay is achieved with over 3.5 GHz bandwidth. The maximum tunable delay can be easily extended to several nanoseconds by modifying the ring coupler κ.
Frequency modulation of an electric field inside of an active medium with a very short gain recovery lifetime has become of recent interest due to the observed and calculated behavior of Quantum Cascade lasers (QCLs) exploiting optical nonlinearities to generate frequency combs in the spectral domain. Thus, in support of better understanding this behavior, we have investigated the effects of stochastic,...
The rapidly growing interest in the mid-IR (2–5μm) wavelengths brings about the need for cheap and CMOS compatible photodetectors. Hereby we demonstrate a plasmonic enhanced Schottky detector in silicon for the mid-IR.
Record high SFDR operation is achieved for heterogeneously integrated silicon photonics modulators, by using hybrid III-V/Si phase modulators within Si MZI modulator structures. 112 dB.Hz2/3 SFDR is achieved at 10 GHz with standard MZI modulators, and 117.5 dB.Hz2/3 for Ring Assisted MZI (RAMZI) modulators.
It has been half a century since the photons have been portended to supplant electrons in information transmission, storage, and processing. While spectacular successes have been achieved in optical communications and these advances are slowly working their way into the chip-scale optical interconnects, optical memories have not displaced magnetic storage and are now losing ground to the all-electronic...
We report on demonstration of GaN tunneling hot electron transistors (THETA) with dc current gain up to 14.5 in common-emitter configuration, which is highest value reported to date in GaN-based hot electron transistors. THETA is a promising candidate to obtain vertical high frequency transistors in GaN. In a THETA, an emitter-base (EB) barrier is applied to tunnel-inject hot electron beams, and a...
Applications of single and coupled microresonators in various photonic switching schemes are considered. It is shown that both single and coupled resonators enhance the performance of the switches based on nonlinear optical or electro-optical effect, but the enhancement occurs at the expense of reduced bandwidth. The critical bit rates at which the enhancement is still possible are derived for single...
We demonstrate the design, fabrication and characterization of plasmonic enhanced silicon photo-detector for infrared light. Theoretical model, experimental results and comparison between different geometric configurations will be presented and discussed.
DC current gain greater than one was demonstrated in GaN tunneling hot electron transistors. At an emitter-base bias of 8 V, dc current gain is increased to 2.8. The results show the promise of GaN tunneling hot electron transistors for the next generation of high-frequency amplifiers. This work is funded by Office of Naval Research under the DATE MURI project (Program manager: Dr. Paul Maki).
We report on accurate modeling of GaN HEMTs for RF operation taking into account sheet charge density (ns) dependence of electron velocity in 2-dimensional electron gases (2DEGs). Electron velocity characteristics of the channel directly impact DC and high frequency transistor performance, and it is critical to understand velocity at all charge density and field conditions to accurately predict large...
This paper described the first results demonstrating the Super-Ring tuning concept applied to a 40 microresonator based TTD device, operating with the Balanced SCISSOR scheme. Tunable delay up to 515ps of a 20GHz BW RF photonic signal was shown, using only two drive voltages, with SFDR over 110dB.Hz2/3 for delays up to 300ps.
An intricate relationship between the intensity of surface-enhanced Raman scattering (SERS) and the optical extinction are revealed. The observed unusual trend of SERS intensity decrease with the increase of extinction is explained analytically and numerically.
Loss in the metal is the main factor restricting practicality of plasmonic and metamaterial devices. In this tutorial the inevitability of the loss, its physical origins and the means to mitigate it will be considered
We demonstrate the detection of subbandgap light in silicon nano pyramid using the process of internal photoemission in Schottky diode. The quantum efficiency is enhanced by using metal coated silicon nano pyramids.
Commercially packaged optical true-time-delay devices were developed utilizing ultra-low loss silicon nitride microresonators, achieving record tunable delay of 535ps for a 20GHz wide signal, 632ps for a 10GHz wide signal, with tunable loss of 3dB.
We investigated hot phonons based on Stokes Raman scattering from a GaN/AlN high electron mobility transistor. Such a simple method is advantageous compared with the method based on Stokes and anti-Stokes Raman scattering.
This paper describes miniature silicon photonics modulators, fabricated in a CMOS compatible technology, suitable for integration with ultra wideband phased array antennas. The Linearized Ring-Assisted Mach-Zehnder Interferometer (L-RAMZI) modulators, formed by integrating two microring phase modulators with an MZI structure, provide linearization of the MZI based modulator transfer characteristic...
We describe a rigorous and physically transparent theory of enhancement of third order nonlinear optical processes achieved in plasmonic structures. The results show that while the effective nonlinear index can be enhanced by many orders of magnitude, due to high metal losses the most relevant figure of merit, the amount of phase shift per one absorption length remains very low.
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