Green silicon photonics

Silicon photonics have provided low-cost communication components for Internet applications and are now aimed towards providing environmentally friendly and green optical solutions. The need for energy-efficient photonics is due to the excessive energy dissipated in advanced electronics and an increase in power density that has posed a challenge to the most advanced chip-cooling technologies. The two-photon absorption (TPA)-generated free carriers need to be actively removed from the waveguide cover to eliminate any event of light absorption and a subsequent conversion to heat. Researchers have proposed an electro-optic modulator that takes advantage of the two-photon photovoltaic (TPPV) effect to attain negative static power dissipation. Photovoltaic power converters (PPC) are used for remote power delivery and are optimized for a wavelength range from 1,200 to 1,550 nm.published_or_final_versio

Extreme Value Statistics in Silicon Photonics

L-shape probability distributions are extremely non-Gaussian functions that have been surprisingly successful in describing the occurrence of extreme events ranging from stock market crashes, natural disasters, structure of biological systems, fractals, and optical rogue waves. We show that fluctuations in stimulated Raman scattering, as well as in coherent anti-Stokes Raman scattering, in silicon can follow extreme value statistics and provide mathematical insight into the origin of this behavior

Mn-doped InAs self-organized diluted magnetic quantum-dot layers with Curie temperatures above 300 K300 K

The magnetic and structural properties of InAs:Mn self-organized diluted magnetic quantum dots grown by low-temperature (∼270 °C)(∼270 °C), solid-source molecular-beam epitaxy using a very low InAs growth rate (<0.1 ML∕s)(<0.1 ML∕s) are investigated. A Curie temperature (TC)(TC) of ∼350 K∼350 K is measured in a sample grown with a Mn∕InMn∕In flux ratio of 0.15. Electron energy-loss spectroscopy confirms that most of the Mn remains within the InAs quantum dots. We propose as a possible explanation for this high TCTC the effects of magnetic and structural disorder introduced by a random incorporation and inhomogeneous distribution of Mn atoms amongst the InAs quantum dots.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69680/2/APPLAB-85-6-973-1.pd

UNA RETÓRICA PARRÉSICA: UNA PROPUESTA DE DOS PRÁCTICAS RETÓRICAS CONTEMPORÁNEAS

O dizer-tudo ou franco-falar (parrhesia) chama-nos a atenção para a necessidade de definir as fronteiras da retórica. Na concepção clássica, parrhesia e a retórica colocavam-se como actividades discursivas incompatíveis entre si. No entanto, algumas actividades comunicacionais marcadamente modernas vieram reconfigurar este espaço de mútua anulação. Perante as transformações que a retórica sofreu com a intensificação da mediatização urge equacionar o grau de influência entre retórica e parrhesia. No que se segue, descreve-seum espaço hodierno de recíproca afectação entre retórica e parrhesia. Por um lado, a parrhesia aparenta manifestar-se retoricamente no discurso publicitário através da sua inclusão enquanto tropo retórico, sendo inclusivamente uma figura indispensável da elocução retórica do ponto de vista do pathos. Por outro lado, a parrhesia parece manifestar-se na própria prática profissional e deontológica do jornalismo como um tipo de discurso intrínseco à própria legitimidade do jornalista. Deste modo, sublinha-se a possibilidade de uma retórica de pendor parrhésico.The free-speech or to speak boldly (parrhesia) calls our attention to the need to define the boundaries of rhetoric. In the classical conception, parrhesia and rhetoric were placed as discursive activities incompatible with each other. However, some distinctly modern communication activities have changed this space of mutual impossibility. Given the changes that rhetoric has suffered with mediatization, it is urgent to ponder the degree of influence between rhetoric and parrhesia. This paper describes today’s reciprocal influence between rhetorical and parrhesia. On the one hand, parrhesia appears to manifest itself rhetorically in advertising discourse as a rhetorical trope and being an indispensable figure of elocution from a pathos’s point of view. On the other hand, parrhesia seems to manifest itself in the professional and ethical practice of journalism as a kind of intrinsic speech that legitimizes journalist activity. Thus, the paper emphasizes the possibility of a Rhetoric of Parrhesic effect.El “decirlo todo” o el “hablar con franqueza” (parresia) nos obligan a la necesidad de definir los límites de la retórica. En la época clásica tanto la parresia como la retórica eran actividades discursivas incompatibles entre si. No obstante, algunas actividades comunicativas modernas vinieron a reconfigurar este espacio de mutua exclusión. Ante las transformaciones que la retórica sufrió con la intensificación de la mediatización urge evaluar el grado de influencia entre la retórica y la parresia. En este artículo se describe un espacio contemporáneo de reciproca asignación entre retórica y parresia. Por un lado, la parresia aparenta manifestarse retóricamente en el discurso publicitario a través de su inclusión como tropo retórico, siendo incluso una figura indispensable de la elocución retórica del punto de vista del pathos. Por otro lado, la parresia parece manifestarse en la propia actividad profesional y deontológica del periodismo como un tipo de discurso intrínseco a la propia legitimidad del periodista. De este modo, se remarca la posibilidad de una retórica de inclinación parrésica.info:eu-repo/semantics/publishedVersio

High-speed quantum dot lasers

The modulation bandwidth of conventional 1.0–1.3 µm self-organized In(Ga)As quantum dot (QD) lasers is limited to ∼6–8 GHz due to hot carrier effects arising from the predominant occupation of wetting layer/barrier states by the electrons injected into the active region at room temperature. Thermal broadening of holes in the valence band of QDs also limits the performance of the lasers. Tunnel injection and p-doping have been proposed as solutions to these problems. In this paper, we describe high-performance In(Ga)As undoped and p-doped tunnel injection self-organized QD lasers emitting at 1.1 and 1.3 µm. Undoped 1.1 µm tunnel injection lasers have ∼22 GHz small-signal modulation bandwidth and a gain compression factor of 8.2 × 10−16 cm3. Higher modulation bandwidth (∼25 GHz) and differential gain (3 × 10−14 cm2) are measured in 1.1 µm p-doped tunnel injection lasers with a characteristic temperature, T0, of 205 K in the temperature range 5–95°C. Temperature invariant threshold current (infinite T0) in the temperature range 5–75°C and 11 GHz modulation bandwidth are observed in 1.3 µm p-doped tunnel injection QD lasers with a differential gain of 8 × 10−15 cm2. The linewidth enhancement factor of the undoped 1.1 µm tunnel injection laser is ∼0.73 at lasing peak and its dynamic chirp is <0.6 ° at various frequencies and ac biases. Both 1.1 and 1.3 µm p-doped tunnel injection QD lasers exhibit zero linewidth enhancement factor (α ∼0) and negligible chirp (< 0.2 °). These dynamic characteristics of QD lasers surpass those of equivalent quantum well lasers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48925/2/d5_13_005.pd

Optical transmission properties of C-shaped subwavelength waveguides on silicon

Optical properties of C-shaped subwavelength waveguides in metallic (silver) films on silicon substrates are studied in the range of 0.6-6 mu m. Power throughput and resonant wavelengths of several transmission modes are studied by varying the waveguide length (or metal thickness). Among three types of transmission modes, the fundamental order of the Fabry-Perot-type mode was shown to attain remarkably high power throughputs (as high as 12). With optimized design of the aperture, the resonant wavelength of this mode occurs in the 1-2 mu m wavelength range, suggesting that such apertures can be utilized to achieve plasmonic-enhanced silicon photonic devices at telecommunication wavelengths

The role of Auger recombination in the temperature-dependent output characteristics (T0=∞)(T0=∞) of pp-doped 1.3 μm quantum dot lasers

Temperature invariant output slope efficiency and threshold current (T0=∞)(T0=∞) in the temperature range of 5–75 °C have been measured for 1.3 μm pp-doped self-organized quantum dot lasers. Similar undoped quantum dot lasers exhibit T0=69 KT0=69 K in the same temperature range. A self-consistent model has been employed to calculate the various radiative and nonradiative current components in pp-doped and undoped lasers and to analyze the measured data. It is observed that Auger recombination in the dots plays an important role in determining the threshold current of the pp-doped lasers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71264/2/APPLAB-85-22-5164-1.pd

Vertical-external-cavity surface-emitting lasers and quantum dot lasers

The use of cavity to manipulate photon emission of quantum dots (QDs) has been opening unprecedented opportunities for realizing quantum functional nanophotonic devices and also quantum information devices. In particular, in the field of semiconductor lasers, QDs were introduced as a superior alternative to quantum wells to suppress the temperature dependence of the threshold current in vertical-external-cavity surface-emitting lasers (VECSELs). In this work, a review of properties and development of semiconductor VECSEL devices and QD laser devices is given. Based on the features of VECSEL devices, the main emphasis is put on the recent development of technological approach on semiconductor QD VECSELs. Then, from the viewpoint of both single QD nanolaser and cavity quantum electrodynamics (QED), a single-QD-cavity system resulting from the strong coupling of QD cavity is presented. A difference of this review from the other existing works on semiconductor VECSEL devices is that we will cover both the fundamental aspects and technological approaches of QD VECSEL devices. And lastly, the presented review here has provided a deep insight into useful guideline for the development of QD VECSEL technology and future quantum functional nanophotonic devices and monolithic photonic integrated circuits (MPhICs).Comment: 21 pages, 4 figures. arXiv admin note: text overlap with arXiv:0904.369

Cardioprotective effects of deferoxamine in acute and subacute cardiotoxicities of doxorubicin: a randomized clinical trial

Background: Cardiotoxicity is a major concern following doxorubicin (DOX) use in the treatment of malignancies. We aimed to investigate whether deferoxamine (DFO) can prevent acute cardiotoxicity in children with cancer who were treated with DOX as part of their chemotherapy. Results: Sixty-two newly-diagnosed pediatric cancer patients aged 2–18 years with DOX as part of their treatment regimens were assigned to three groups: group 1 (no intervention, n = 21), group II (Deferoxamine (DFO) 10 times DOX dose, n = 20), and group III (DFO 50 mg/kg, n = 21). Patients in the intervention groups were pretreated with DFO 8-h intravenous infusion in each chemotherapy course during and after completion of DOX infusion. Conventional and tissue Doppler echocardiography, serum concentrations of human brain natriuretic peptide (BNP), and cardiac troponin I (cTnI) were checked after the last course of chemotherapy. Sixty patients were analyzed. The level of cTnI was < 0.01 in all patients. Serum BNP was significantly lower in group 3 compared to control subjects (P = 0.036). No significant differences were observed in the parameters of Doppler echocardiography. Significant lower values of tissue Doppler late diastolic velocity at the lateral annulus of the tricuspid valve were noticed in group 3 in comparison with controls. By using Pearson analysis, tissue Doppler systolic velocity of the septum showed a marginally significant negative correlation with DOX dose (P = 0.05, r = − 0.308). No adverse effect was reported in the intervention groups. Conclusions: High-dose DFO (50 mg/kg) may serve as a promising cardioprotective agent at least at the molecular level in cancer patients treated with DOX. Further multicenter trials with longer follow-ups are needed to investigate its protective role in delayed DOX-induced cardiac damage. Trial registration IRCT, IRCT2016080615666N5. Registered 6 September 2016