Er3+Ylif4 Continuous Wave Cascade Laser Operation At 1620 And 2810 Nm At Room-Temperature

For the first time cw, cascade lasing was demonstrated in 1% Er doped yttrium lithium fluoride (YLF) at room temperature at both 1620 and 2810 nm. In addition, cw lasing in Er[1%]:YLF at 1640 nm and in Er[5%]:YLF at 2810 nm at room temperature is reported for the first time in material of such low concentration

Wavelength tuning of fiber lasers using multimode interference effects

We report on a novel scheme to fabricate a simple, cheap, and compact tunable fiber laser. The tuning is realized by splicing a piece of single-mode fiber to one end of an active double-clad fiber, while the other end of the single-mode fiber is spliced to a 15 mm long section of 105/125 multimode fiber. The fluorescence signal entering into the multimode fiber will be reproduced as single images at periodic intervals along the propagation direction of the fiber. The length of the multimode fiber is chosen to be slightly shorter than the first re-imaging point, such that the signal coming out from the single mode fiber is obtained in free space, where a broadband mirror retroreflects the fluorescence signal. Since the position of the re-imaging point is wavelength dependent, different wavelengths will be imaged at different positions. Therefore, wavelength tuning is easily obtained by adjusting the distance between the broadband mirror and the multimode fiber facet end. Using this principle, the tunable fiber laser revealed a tunability of 8 nm, ranging from 1088-1097 nm, and an output power of 500 mW. The simplicity of the setup makes this a very cost-effective tunable fiber laser

Widely tunable erbium-doped fiber laser based on multimode interference effect

A widely tunable erbium-doped all-fiber laser has been demonstrated. The tunable mechanism is based on a novel tunable filter using multimode interference effects (MMI). The tunable MMI filter was applied to fabricate a tunable erbium-doped fiber laser via a standard ring cavity. A tuning range of 60 nm was obtained, ranging from 1549 nm to 1609 nm, with a signal to noise ratio of 40 dB. The tunable MMI filter mechanism is very simple and inexpensive, but also quite efficient as a wavelength tunable filter

Using smart phone mobility traces for the diagnosis of depressive and manic episodes in bipolar patients

open8siIn this paper we demonstrate how smart phone sensors, specifically inertial sensors and GPS traces, can be used as an objective "measurement device" for aiding psychiatric diagnosis. In a trial with 12 bipolar disorder patients conducted over a total (summed over all patients) of over 1000 days (on average 12 weeks per patient) we have achieved state change detection with a precision/recall of 96%/94% and state recognition accuracy of 80%. The paper describes the data collection, which was conducted as a medical trial in a real life every day environment in a rural area, outlines the recognition methods, and discusses the results.openGruenerbl, Agnes; Osmani, Venet; Bahle, Gernot; Carrasco, Jose C.; Oehler, Stefan; Mayora, Oscar; Haring, Christian; Lukowicz, PaulGruenerbl, Agnes; Osmani, Venet; Bahle, Gernot; Carrasco, Jose C.; Oehler, Stefan; Mayora, Oscar; Haring, Christian; Lukowicz, Pau

Ultra-Compact Multimode Interference Ingaasp Multiple Quantum Well Modulator

We propose a new structure for an ultra-compact multimode interference (MMI) InGaAsP multiple quantum well modulator. The operating principle is based on restricting the coupling of the self-image produced by the MMI region into a single mode output waveguide. The key is to excite only the even modes within the MMI region, and this is achieved by operating the MMI waveguide under the condition of restricted symmetric interference. By asymmetrically inducing a phase change of π along a selected area within the MMI region, mode conversion of all the even modes to odd modes is achieved. Since only the fundamental mode can be coupled to the output waveguide, neither an individual mode, nor any combination of the modes will be coupled, and therefore the injected light is fully attenuated. The modulation characteristics are analyzed using the finite-difference beam propagation method. Extinction ratios as low as -37 dB are demonstrated without electro-absorption effects. For the case of low electro-absorption, which corresponds to a more realistic situation, this value is only increased to -35 dB. © 2005 Springer

Connecting personal-scale sensing and networked community behavior to infer human activities

Advances in mobile and wearable devices are making it fea-sible to deploy sensing systems at a large-scale. However, slower progress is being made in activity recognition which remains often unreliable in everyday environments. In this paper, we investigate how to leverage the increasing capacity to gather data at a population-scale towards improving ex-isting models of human behavior. Specifically, we consider the various social phenomena and environmental factors that cause people to develop correlated behavioral patterns, es-pecially within communities connected by strong social ties. Reasons underpinning correlated behavior include shared ex-ternalities (e.g., work schedules, weather, traffic conditions), that shape options and decisions; and cases of adopted behav-ior, as people learn from each other or assume group norms due to social pressure. Most existing approaches to modeling human behavior ignore all of these phenomena and recognize activities solely on the basis of sensor data captured from a single individual. We propose the Networked Community Be-havior (NCB) framework for activity recognition, specifically designed to exploit community-scale behavioral patterns. Un-der NCB, patterns of community behavior are mined to iden-tify social ties that can signal correlated behavior, this infor-mation is used to augment sensor-based inferences available from the actions of individuals. Our evaluation of NCB shows it is able to outperform existing approaches to behavior mod-eling across four mobile sensing datasets that collectively re-quire a diverse set of activities to be recognized