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Generating green to red light with semiconductor lasers  [PDF]
Gabriele Ferrari
Physics , 2007, DOI: 10.1364/OE.15.001672
Abstract: Diode lasers enable one to continuously cover the 730 to 1100 nm range as well as the 370 to 550 nm range by frequency doubling, but a large part of the electro-magnetic spectrum spanning from green to red remains accessible only through expensive and unpractical optically pumped dye lasers. Here we devise a method to multiply the frequency of optical waves by a factor 3/2 with a conversion that is phase-coherent and highly efficient. Together with harmonic generation, it will enable one to cover the visible spectrum with semiconductor lasers, opening new avenues in important fields such as laser spectroscopy and optical metrology.
Division algebras with the same maximal subfields  [PDF]
Vladimir I. Chernousov,Andrei S. Rapinchuk,Igor A. Rapinchuk
Mathematics , 2015, DOI: 10.1070/RM2015v070n01ABEH004937
Abstract: We give a survey of recent results related to the problem of characterizing finite-dimensional division algebras by the set of isomorphism classes of their maximal subfields. We also discuss various generalizations of this problem and some of its applications. In the last section, we extend the problem to the context of absolutely almost simple algebraic groups.
On division algebras having the same maximal subfields  [PDF]
A. S. Rapinchuk,I. A. Rapinchuk
Mathematics , 2009,
Abstract: We address the problem of when two finite dimensional central division algebras over the same field are necessarily isomorphic given that they have the same maximal subfields.
Control of period-one oscillation for all-optical clock division and clock recovery by optical pulse injection driven semiconductor laser

Li Jing-Xi,Zhang Ming-Jiang,Niu Sheng-Xiao,Wang Yun-Cai,

中国物理 B , 2008,
Abstract: The period-one oscillation produced by an external optical pulse injection driven semiconductor laser is applied to clock recovery and frequency division. By adjusting the repetition rate or injection power of the external injection optical pulses to lock the different harmonic frequencies of the period-one state, the clock recovery and the frequency division (the second and third frequency divisions) are achieved experimentally. In addition, in frequency locking ranges of 2GHz and 1.9GHz, the second and third frequency divisions are obtained with the phase noise lower than --100dBc/Hz, respectively. Our experimental results are consistent well with the numerical simulations.
Remote-Time Division Multiplexing of Bending Sensors Using a Broadband Light Source
Mikel Bravo,Manuel López-Amo
Journal of Sensors , 2012, DOI: 10.1155/2012/154586
Abstract: This work experimentally demonstrates a remote sensing network which interrogates bending sensors using time-division multiplexing techniques and a broadband light source. The bending sensors are located 50 km away from the monitoring station. They are based on a simple tie displacement sensor and offer high-resolution measurements of displacement.
Frequency-tunable all-optical clock division using semiconductor laser subjected to external optical injection

Niu Sheng-Xiao,Zhang Ming-Jiang,An Yi,He Hu-Cheng,Li Jing-Xia,Wang Yun-Cai,

物理学报 , 2008,
Abstract: All-optical time division was obtained in the frequency range from 9.0GHz to 19.8GHz. Nonlinear dynamics of a Fabry-Perot laser diode subjected to external optical injection is applied for all-optical clock division. The research results indicate that semiconductor laser subjected to external light injection performs period-one oscillation. We obtain the clock division of the signal pulses when the second harmonic frequency of the period-one oscillation approaches the repetition rate of the signal pulse, and the second harmonic and the fundamental frequency of the period-one oscillation were locked by the signal pulses simultaneously. Numerical simulation was performed on the all-optical time division with signal pulse injection using the rate equation of the semiconductor laser. The simulation result is in good agreement with the experiment. Phase noise level of the divided clock is observed to be smaller than -90 dBc/Hz over a frequency detuning range of 1.5GHz by changing the repetition rate of signal pulses under the fixed wavelength detuning value and input signal pulse power.
Bending of light caused by gravitation: the same result via totally different philosophies  [PDF]
Tolga Yarman,Alexander Kholmetskii,Metin Arik
Physics , 2014,
Abstract: We offer a concise and direct way to derive the bending angle of light (i.e. as generally called, gravitational lensing), while light grazes a star, through the approach suggested earlier by the first author, which is fundamentally based on the energy conservation law and the weak equivalence principle. We come out with the same result as that of the general theory of relativity (GTR), although the philosophies behind are totally different from each other. We emphasize that in our approach, there is no need to draw a distinction between light and ordinary matter, which makes our approach of gravity potentially compatible with quantum mechanics. Furthermore, our equation that furnishes gravitational lensing, also furnishes the result about the precession of the perihelion of a planet. The results obtained are discussed.
Burn-In Aging Behavior and Analytical Modeling of Wavelength-Division Multiplexing Semiconductor Lasers: Is the Swift Burn-In Feasible for Long-Term Reliability Assurance?  [PDF]
Jia-Sheng Huang
Advances in OptoElectronics , 2013, DOI: 10.1155/2013/568945
Abstract: Effective and economical burn-in screening is important for technology development and manufacture of semiconductor lasers. We study the burn-in degradation behavior of wavelength-division multiplexing semiconductor lasers to determine the feasibility of short burn-in. The burn-in is characterized by the sublinear model and correlated with long-term reliability. 1. Introduction As the demand of data, voice, and video play grows, the bandwidth requirement for downstream and upstream transmissions continues to increase. Recently, there has been accelerated growth in bandwidth demand due to the introduction of mobile smart phones and portable touch screen tablets (iPhone, iPad, etc.). Wavelength-division multiplexing has been the enabling technology for higher bandwidth. To meet the WDM applications where a high density of channels is in service, each channel requires superior reliability and wavelength stability. Some network and cable operators have tightened up their wavelength stability from 0.1?nm to 0.03–0.09?nm [1–4]. On the other hand, there has been an ongoing driver to reduce the manufacturing cost and cycle time of the laser components. One way to achieve the lower cost is by means of qualification improvement. In this paper, we study the burn-in behavior of the WDM distributed feedback (DFB) lasers and correlate it with long-term reliability. We characterize the burn-in behavior using sublinear model and determine the burn-in times. We also correlate the burn-in with the long-term life test. We demonstrate that swift burn-in screen of BH lasers is feasible while meeting the long-term WDM reliability requirement. 2. Experimental The buried heterostructure (BH) DFB lasers with C-band (1550?nm and vicinity) lasing wavelength were used for the study. Epitaxial layers were grown on n-type InP substrate using metal organic chemical vapor deposition (MOCVD) technique. First, n-doped InP buffer layer was grown. An active layer consisting of multiquantum well structures and grating layers were grown sequentially. The composition of the active region was InGaAsP. A mesa structure was formed by wet etch. Subsequently, p-InP and n-InP burying layers were grown to form current blocking. The final regrowth layer was grown, etched into mesa structure, and covered with SiNx/SiO2 dielectric layers. The contact opening in the dielectric was created by reactive ion etching (RIE), and the p-metallization stack of Ti/Pt/Au/Cr/Au was deposited to make ohmic contact. On the n-side, the wafer was thinned by lapping and deposited with AuGe/Ni/Au to form n-contact.
Spin Currents in Semiconductor Nanostructures: A Nonequilibrium Green-Function Approach  [PDF]
Branislav K. Nikolic,Liviu P. Zarbo,Satofumi Souma
Physics , 2009,
Abstract: This chapter of "The Oxford Handbook of Nanoscience and Technology: Frontiers and Advances" reviews nonequilibrium Green function (NEGF) approach to modeling spin current generation, transport, and detection in semiconductor nanostructures containing different types of spin-orbit (SO) couplings. Its tutorial style--with examples drawn from the field of the spin Hall effects (SHEs) and with treatment of the Rashba, Dresselhaus and extrinsic SO couplings--offers practical recipes to compute total spin and charge currents flowing out of the device, as well as the nonequilibrium local spin densities and spin fluxes within the multiterminal nanostructure. These quantities, which are obtained from the knowledge of spin-resolved NEGFs that can describe both ballistic and diffusive transport regimes while handling phase-coherent effects or dephasing mechanisms relevant at room temperature, can be employed to understand recent experiments on all-electrical detection of mesoscopic and quantum SHE in complicated low-dimensional nanostructures, as well as to model a multitude of "second generation" spintronic devices exploiting coherent spin dynamics. The chapter also provides extensive coverage of relevant technical and computational details, such as: (i) the construction of retarded and lesser Green functions for SO-coupled nanostructures attached to many electrodes; (ii) computation of self-energies introduced by different types of electrodes attached to the central region; and (iii) accelerated algorithms for NEGF evaluation that make possible spin transport modeling in devices of the size comparable to the spin precession length (typically few hundreds of nanometers) that sets the scale where mesoscopic SHE effect in ballistic SO-coupled nanostructures is expected to reach its optimal magnitude.
Nonequilibrium Green's function theory of coherent excitonic effects in the photocurrent response of semiconductor nanostructures  [PDF]
U. Aeberhard
Physics , 2012, DOI: 10.1103/PhysRevB.86.115317
Abstract: Excitonic contributions to absorption and photocurrent generation in semiconductor nanostructures are described theoretically and simulated numerically using steady-state non-equilibrium Green's function theory. In a first approach, the coherent interband polarization including Coulomb corrections is determined from a Bethe-Salpeter-type equation for the equal time interband single-particle charge carrier Green's function. The effects of excitonic absorption on photocurrent generation are considered on the same level of approximation via the derivation of the corresponding corrections to the electron-photon self-energy.
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