Detection of Nitric Oxide with Faraday Rotation Spectroscopy at 5.33μm

We report the development of a static magnetic eld Faraday rotation spectrometer for NO detection.A 5.33μm continuous-wave quantum cascade laser was used as the probing laser.Line absorption at 1875.81 cm^−1(2Π3=2Q(3/2),v=1←0)was chosen for the detection.By using a Chernin type multipass cell,a detection precision of 1.15 ppbv(1σ,1s)was achieved with an absorption pathlength of 108 m.This value was reduced to 0.43 ppbv by increasing the data-acquisition time to 15 s.

YbBi:YIG石榴石单晶的磁光性能及其光纤电流传感器应用

Magneto optic(MO) fiber current sensors utility the Faraday effect of magneto op tic materials to sensing the magnetic(current)fields.The optical fiber sensors(O FS)offer great advantages of simple structure,high reliability,high accuracy and sensibility,immunity to electromagnetic interference.They are the most promised method to substitute the conventional current transducers(CTs),much attentions were focused on both domestic and abroad.Magneto optic properties of Faraday se n sing element have much affect on the performance of the optical fiber current se nsor.For used in the sensor system,MO materials with magneto optic characterist i cs of large Faraday rotation(FR)angle θ f ,low temperature sensibility,and suitable saturation field were general demanded. Development of MO materials is one of the most important problems of optical fiber current sensor research. In this paper,one mixed doped Bi substituted yttrium iron garnet crystal BiYb:Y I G, which has large and temperature stable FR angle,was grown from high temperatu re flux.By taking PbO+PbF 2 as the main flux,under the compositions of molar ra tio Y 2O 3:Yb 2O 3:Bi 2O 3:Fe 2O 3:(PbO+PbF 2+B 2O 3+CaCO 3)=7.64:1. 04:1.74:20.78:78:68.8,crystals of quite good quality were grown from melt flux,t he largest one has the size of 22mm×15mm×12mm.Magneto optic proprieties of Fa raday rotation angle and optical absorption spectrum of the BiYb:YIG crystal,expecial ly Y 2.289 Yb 0.246 Bi 0.465 Fe 5O 12 ,in the range of 0.7 1.9 μm waveband were measured.At λ =1.55μm,the BiYb:YIG crystal has special Fa raday rotation angle of -404deg/cm,temperature coefficient 4.2×10 -6 K -1 ,optical absorption coefficient 3.6cm -1 ,and figure of merit 25.8deg/dB . The results indicate that substituted with Bi 3+ can largely improve the Fa raday rotation of rear earth iron garnets.Because Faraday rotation angles of Yb 3Fe 5O 12 and Y 3Fe 5O 12 have opposite temperature dependency,ut ility the compensation effect of mix doped,co doped with some other ions,such a s Yb 3+ ,would decrease the temperature dependency of Bi substituted garnet. So the garnet crystal BiYb:YIG has high and temperature stable Faraday rotation an gle,very suitable to be used as Faraday effect materials for high sensibility an d temperature stable Optical fiber current sensors.Using BiYb:YIG as Faraday rot ation cell,a hybrid bulk crystal optical fiber current sensor was proposed and t ests under direct current(DC) and 50Hz alternating current(AC).The performance c haracteristics of the sensors system were:DC measurement,sensibility 0.01A, l inea rity 1.1%;AC measurement,sensibility 9.5A/mV ,accuracy ±1%,linearity 1.1%,dynam ic range 40dB.In conclusion,Faraday effect magneto optic optical fiber current sensors have higher sensibility and accuracy than conventional CTs.

A review of methods for mitigating ionospheric artifacts in differential SAR interferometry

Interferometric synthetic aperture radar(InSAR)has been widely used to measure ground displacements related to geophysical and anthropic activities over the past three decades.Satellite SAR systems use microwave signals that interact with the ionosphere when they travel through it during the imaging processes.In this context,ionospheric variations can significantly contaminate SAR imagery,which in turn affects spaceborne InSAR measurements.This bias also leads to a decrease in the coherence and accuracy of InSAR measurements,especially for the low-frequency SAR systems.In this paper,we give an overview of the latest methods for mitigating the ionospheric contributions in InSAR,including Faraday rotation method,azimuth shift method,and range split-spectrum method,and only focus on the single pair of InSAR interferograms.The current challenges and future perspectives are outlined at the end of this paper.

Optical measurements and analytical modeling of magnetic field generated in a dieletric target

Polarization rotation of a probe pulse by the target is observed with the Faraday rotation method in the interaction of an intense laser pulse with a solid target. The rotation of the polarization plane of the probe pulse may result from a combined action of fused silica and diffused electrons.After the irradiation of the main pulse, the rotation angle changed significantly and lasted^2 ps.These phenomena may imply a persistent magnetic field inside the target. An analytical model is developed to explain the experimental observation. The model indicates that a strong toroidal magnetic field is induced by an energetic electron beam. Meanwhile, an ionization channel is observed in the shadowgraph and extends at the speed of light after the irradiation of the main beam. The formation of this ionization channel is complex, and a simple explanation is given.

Tunable and switchable polarization rotation with non-reciprocal plasmonic thin films at designated wavelengths

We experimentally demonstrate an ultra-thin plasmonic optical rotator in the visible regime that induces a polarization rotation that is continuously tunable and switchable by an external magnetic field.The rotator is a magneto-plasmonic hybrid structure consisting of a magneto-optical EuSe slab and a one-dimensional plasmonic gold grating.At low temperatures,EuSe possesses a large Verdet constant and exhibits Faraday rotation,which does not saturate over a regime of several Tesla.By combining these properties with plasmonic Faraday rotation enhancement,a large tuning range of the polarization rotation of up to 8.4° for a film thickness of 220 nm is achieved.Furthermore,through experiments and simulations,we demonstrate that the unique dispersion properties of the structure enable us to tailor the wavelengths of the tunable polarization rotation to arbitrary spectral positions within the transparency window of the magneto-optical slab.The demonstrated concept might lead to important,highly integrated,non-reciprocal,photonic devices for light modulation,optical isolation,and magnetic field optical sensing.The simple fabrication of EuSe nanostructures by physical vapor deposition opens the way for many potentially interesting magneto-plasmonic systems and three-dimensional magneto-optical metamaterials.