Search results for "HIF"
showing 10 items of 1515 documents
A Computational Study on Temperature Variations in MRgFUS Treatments Using PRF Thermometry Techniques and Optical Probes
2021
Structural and metabolic imaging are fundamental for diagnosis, treatment and follow-up in oncology. Beyond the well-established diagnostic imaging applications, ultrasounds are currently emerging in the clinical practice as a noninvasive technology for therapy. Indeed, the sound waves can be used to increase the temperature inside the target solid tumors, leading to apoptosis or necrosis of neoplastic tissues. The Magnetic resonance-guided focused ultrasound surgery (MRgFUS) technology represents a valid application of this ultrasound property, mainly used in oncology and neurology. In this paper
phase-locked soliton pairs in a fiber ring laser
2002
We have experimentally observed the formation of stable pulse pairs with a π/2 phase difference in a passively mode-locked stretched-pulse fiber ring laser. We have developed a simplified theoretical model that, keeping the essential features of the experiment, reduces greatly the number of free parameters and solved it numerically. The agreement with the experimental results is excellent.
Silicon-microring into a fiber laser cavity for high-repetition-rate pulse train generation
2017
International audience; In 1997, Yoshida et al. inserted a Fabry-Perot filter in a modulation instability fiber laser cavity [1], the free spectral range (FSR) of the Fabry-Perot fixed the RF to 115 GHz; however the pulsed laser was poorly stable. Since then, lasers of increasing performance have been demonstrated using variants of this method. In 2012, Peccianti et al., demonstrated the first fiber laser harmonically mode-locked by integrated high-finesse microresonator [2]. The doped silica, on-chip microresonator provided both high spectral selectivity and nonlinearity, thus promoting the dynamics pulsed at 200 GHz. By using a silicon microring resonator (SMRR), this approach lead to the…
Parabolic pulse generation with dispersion decreasing optical fiber
2007
We experimentally demonstrate the possibility to generate parabolic pulses via a single dispersion decreasing optical fiber with normal dispersion. We numerically and experimentally outline the influence of the dispersion profile.
Passive compensation of the thermal drift of magnetostriction based Q-switched fiber lasers
2009
Abstract The authors propose and demonstrate a method to compensate the thermal drift of magnetostriction based Q-switched fiber lasers, which is caused by the eddy currents induced in the Terfenol-D magnetostrictive actuators. The consequent wavelength detuning between the fiber gratings of the laser is passively compensated by the use of Monel 400 as thermal actuator of the non-modulated grating. A highly stable pulsed signal is achieved in the range of 1 Hz–5 kHz, with a wavelength detuning between gratings maintained below 10 pm. Furthermore, an optimization of the use of the pump power is proposed, utilizing part of it for simultaneously pumping a fiber optic based amplification stage.
Novel in-line fiber-optic filters and polarisers
2005
Novel in-line devices, based on a tapered fiber whose uniform waist has been metal-coated, are reported. The resonant excitation of a surface plasma mode of the metal film allows for the design of wavelength filters and polarisers
Photonic-crystal fiber-based pressure sensor for dual environment monitoring.
2014
In this paper the development of a side-hole photonic-crystal fiber (SH-PCF) pressure sensor for dual environment monitoring is reported. SH-PCF properties (phase and group birefringence, sensitivity to pressure variations) are measured and compared to simulated data. In order to probe two environments, two sections of the SH-PCF with different lengths are spliced and set in a Solc filter-like configuration. This setup allows obtaining the individual responses of the first and second fiber independently, which is useful for a space-multiplexed measurement. As the employed fiber is sensitive to pressure variations, we report the use of this configuration for dual environment pressure sensing.
Improving mid-infrared supercontinuum generation efficiency by pumping a fluoride fiber directly into the anomalous regime at 1995 nm
2011
Supercontinuum sources in the mid-infrared may found many potential applications to spectroscopy and material caracterization. Supercontinuum light extending up to 4000 nm has been efficiently generated in fluorozirconate glasses (ZBLAN) with 10.5 W power using an amplified nanosecond pulsed laser diode at 1550 nm [1]. As the dispersion wavelength of the fiber is closed to 1700 nm, pumping at 1550 nm does not directly allow generation of solitons. A first approach is thus to pump a piece of SMF fiber in the anomalous dispersion regime to generate the solitons and shift them to the anomalous dispersion regime of the ZBLAN fiber [1,2]. Another approach is to use a high power femtosecond laser…
Experiments with a fiber-based optical dipole trap for cold Cs-Atoms
2011
Pulling a standard optical fiber to a diameter of less than the wavelength of the guided light causes the light field to project slightly over the fiber boundaries in form of an evanescent wave. The latter can be used for light-matter-interactions in the vicinity of the surface of the fiber and therefore allows to perform quantum optic experiments.
Orientation of199mHg by optical pumping detected by ?-radiation anisotropy
1975
199mHg was produced and mass separated at the ISOLDE facility (CERN). Nuclear orientation achieved by optical pumping via the resonance line 6s21S0→6s6p3P1,λ=2537A was monitored by means of the anisotropy of theγ-radiation emitted in the cascade199mHg(I=13/2+) $${}^{199m}Hg(I = 13/2^ + )\xrightarrow[{M4}]{}{}^{199*}Hg(I = 5/2^ - )\xrightarrow[{E2}]{}{}^{199}Hg(I = 1/2^ - ).$$ 199*Hg(I=5/2−)199Hg(I=1/2−).