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In order to obtain analytical gain expression in Brillouin optical Fiber Amplifiers (BFAs), coupled intensity equations describing the interaction of pump and stokes waves must be solved simultaneously. For long optical fibers, although fiber loss is responsible for the pump depletion and nonnegligible effect, for short optical fibers less than 2 km, its effect can be discarded. In this paper, we provide an accurate analytic expression for the BFA gain for fiber lengths less than 2 km by discarding the optical fiber loss and show results of experimental validation.

A simple approach is proposed for determining peak frequencies, stress heights, stress lengths, full-width at half-maximum (FWHM), broadening and symmetry properties, of a composite Brillouin Gain Spectrum (BGS) which is obtained for the pulse lengths longer than the embedded stress lengths. The composite BGS is thus reconstructed in terms of extracted components. It is validated that the method is successful in determining every level of stress peaks and heights embedded in composite BGS.

Room-temperature highly sensitive microbolometers are becoming very attractive in infrared (IR) sensing with the increase in demand for the internet of things (IOT), night vision, and medical imaging. Different techniques, such as building extremely small-scale devices (nanotubes, etc.) or using 2D materials, showed promising results in terms of high sensitivity with the cost of challenges in fabrication and low-noise readout circuit. Here, we propose a new and simple technique on the application of joule heating on a clamped&ndash, clamped beam without adding any complexity. It provides much better uniformity in temperature distribution in comparison to conventional joule heating, and this results in higher thermal stresses on fixed ends. This consequently brings around 60.5&times, improvement in the overall temperature sensitivity according to both theory and COMSOL (multiphysics solver). The sensitivity increased with the increase in the stiffness constant, and it was calculated as 134 N/m for a device with a 60.5&times, improvement. A considerable amount of decrease in the operation temperature (36&times, below 383 K and 47&times, below 428 K) was achieved via a new technique. That&rsquo, s why the proposed solution can be used either to build highly reliable long-term devices or to increase the thermal sensitivity.

An efficient silicon-based light source presents an unreached goal in the field of photonics, due to Silicon’s indirect electronic band structure preventing direct carrier recombination and subsequent photon emission. Here we utilize inelastically tunneling electrons to demonstrate an electrically-driven light emitting silicon-based tunnel junction operating at room temperature. We show that such a junction is a source for plasmons driven by the electrical tunnel current. We find that the emission spectrum is not given by the quantum condition where the emission frequency would be proportional to the applied voltage, but the spectrum is determined by the spectral overlap between the energy-dependent tunnel current and the modal dispersion of the plasmon. Experimentally we find the highest light outcoupling efficiency corresponding to the skin-depth of the metallic contact of this metal-insulator-semiconductor junction. Distinct from LEDs, the temporal response of this tunnel source is not governed by nanosecond carrier lifetimes known to semiconductors, but rather by the tunnel event itself and Heisenberg’s uncertainty principle. Finally We discuss a path for single photon emission via the Coulomb blockade effect leading to single electron tunneling.

Goktas, Hasan/0000-0002-2195-9531 WOS: 000454463000028 A silicon-based light source presents an unreached goal in the field of photonics due to silicon's indirect electronic band structure preventing direct carrier recombination and subsequent photon emission. Here, we utilize inelastically tunneling electrons to demonstrate an electrically driven light emitting silicon-based tunnel junction operating at room temperature. We show that such a junction is a source for plasmons driven by the electrical tunnel current. We find that the emission spectrum is not given by the quantum condition where the emission frequency would be proportional to the applied voltage, but the spectrum is determined by the spectral overlap between the energy-dependent tunnel current and the modal dispersion of the plasmon. By coupling an internal electric field enhancement with an external k-vector matching grating, we were able to demonstrate a 10-fold increase in the internal efficiency and a 40-fold increase in overall quantum efficiency. Such an electron tunneling-based mechanism could lead to a new class of solid-state light sources with unique features such as down-scalability and temporal responses that are significantly shorter than that of light-emitting diodes. Air Force Office of Scientific ResearchUnited States Department of DefenseAir Force Office of Scientific Research (AFOSR) [FA9550-17-1-0377] V.S. is supported by Air Force Office of Scientific Research under the Award FA9550-17-1-0377. We thank Josh Conway for helpful discussions and Ergun Simsek for numerical analysis support.

We show that inelastically-scattering tunnel electrons are a source for electric plasmon generation. We experimentally demonstrate such electrically-driven light-emitting tunnel junction by forward biasing a Fermi sea against a doped semiconductor across a nanometer-thin tunnel gap. Light emission at room temperature is found in the visible frequency range corresponding to a spectral power dependency of the tunnel current and the plasmonic mode. The response time (speed) of such a tunnel junction scales inverse exponentially with the tunnel gap thickness approaching Tpbs for

Goktas, Hasan/0000-0002-2195-9531 WOS: 000424678900006 PubMed: 29400726 We report on an accurate closed-form analytical model for the gain of a Brillouin fiber amplifier that accounts for material loss in the depleted pump regime. We determined the operational model limits with respect to its relevant parameters and pump regimes through both numerical and experimental validation. As such, our results enable accurate performance prediction of Brillouin fiber amplifiers operating in the weak-pump, high-gain, and saturation regimes alike. (C) 2018 Optical Society of America

International audience; We demonstrate the effectiveness of silicon phase masks to implement spatially resolved, multispectral imaging capabilities in the range of terahertz frequencies, using a standard setup of basic interest for time-domain spectrometry with a single-cell source and a single-cell detector. Our principle primarily aims at the development of robust and inexpensive systems. It consists of appropriate space-to-time encoding, in order to ensure single-scan triggering and then take advantage of rapid and self-consistent measurements in the two-dimensional space. The process enables very efficient discrimination giving access to a relevant spatial resolution in the analysis of small size, planar assemblies made of inhomogeneous materials. Benchmark results are provided to validate the concept, thanks to prototyping phase masks with 2×2 pixels, prior evidencing actual performance limitations in the case of 3×3 pixels. Due to the frequency bandwidth of 0.1–1.5THz in our setup and to the available operating conditions, currently acceptable pixel resolutions lie in the range of 3–4mm. Numerical modeling by means of finite elements helps to discuss these numbers and to investigate the relevant theoretical issues, figuring the main propagation issues in connection with a sub-picosecond seed pulse throughout various masks. This involves diffraction and trailing edge effects when crossing the mask together with residual, parasitic reflections. Finally, we give a consistent prospective for improved performance, via realistic updates regarding the architecture of the setup and complementary post-processing. Further values for the attainable spatial resolution then range from 5×5 to 6×6 pixels.