We demonstrate the fabrication of long-period fiber gratings (LPFGs) written in two-mode (TMF) by CO2 laser. Both uniform and tilted LPFGs were fabricated to provide light coupling between LP01 mode LP11 with a efficiency more than 99%. The writing bandwidth LPFG converter can be adjusted changing tilt angle TMF-LPFGs. torsion sensitivity conventional converters measured 0.37 nm/(rad/m) 0.50 nm/(rad/m), respectively. Two orthogonal vector modes (the HEeven 21and HEodd 21 modes) corresponding...

Sea ice freeboard heights in the Weddell of Antarctica are derived from Ice, Cloud, and Land Elevation Satellite (ICESat) laser altimeter measurements, which have a unique range precision to flat surfaces 2 cm within 70 m footprints spaced at 172 along track. Although elevations can be obtained an accuracy ∼10 (1 σ ) per footprint, direct determination is precluded by errors knowledge geoid temporal variability ocean surface. Therefore freeboards determined relative reference level detected...

We investigated an all-fiber mode converter based on long-period fiber gratings (LPFGs) written in the few-mode fiber. Mode conversion between fundamental core and different higher-order modes (LP11, LP21, LP02 modes) can be realized via a single LPFG with efficiency of 99% at resonance wavelength. Moreover, optimized LP01 LP21 by cascading two LPFGs grating pitches. The maximum is estimated to ∼99.5% 1553 nm. orbital angular momentum states topological charges (±1,±2) are demonstrated...

We demonstrate the fabrication of helical long-period grating (HLPG) in a two-mode fiber (TMF) with CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser. The torsion characteristics gratings are experimentally investigated. It was found that resonance wavelength TMF-HLPG linearly shifts twist sensitivity 0.47 nm/(rad/m), which is an order magnitude higher than conventional (LPFGs). temperature TMF-HPFG measured to be 23.9 pm/°C, one...

During the recent Asian Seas International Acoustics Experiment (ASIAEX), extensive current meter moorings were deployed around continental shelf-break area in northeastern South China Sea. Thirteen RADARSAT SAR images collected during field test to integrate with situ measurements from moorings, ship-board sensors, and conductivity/temperatire/depth (CTD) casts. Besides providing a synoptic view of entire region, satellite imagery is very useful for tracking internal waves, locating surface...

We demonstrate the fabrication of helical long-period gratings (HLPGs) in a polarization-maintaining fiber using CO2 laser. The maximum polarization-dependent loss (PDL) grating was measured to be more than 30 dB at resonance wavelength. HLPG found have high refractive index sensitivity -7248.6 nm/RIU when surrounding changes range 1.4470-1.4600, temperature 158.8 pm/°C, and strain 3.17 pm/με. twist sensitivities based on intensity variation were 5.98 dB/(rad/m) (co-directional twist) -5.97...

A high-sensitivity curvature sensing configuration is implemented by using a fiber Mach-Zehnder interferometer (MZI) with D-shaped Bragg grating (FBG). segment of fusion spliced into single mode at both sides, and then short FBG inscribed in the fiber. The device yields significant spectrum sensitivity as high 87.7 nm/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> to ultralow range from 0 0.3 m , can distinguish orientation...

We demonstrate a directional curvature sensor based on tilted few-mode fiber Bragg gratings (FM-FBGs) inscribed by UV laser. The eigenmodes of LP01 and LP11 mode groups are simulated along with the bending. is resonance in FM-FBG. For from 4.883 to 7.625 m−1, sensitivities at direction 0° 90° measured be −2.67 0.128 dB/m−1, respectively. temperature variation barely affects depth mode. proposed clearly demonstrates potential simultaneous measurement resolutions 9.15×10−4 m−1 0.952°C,

We propose a novel fiber device based on arc-induced long-period gratings (LPFGs) in hollow core silica capillary. This is made up of lead-in single-mode (SMF), LPFGs capillary (CLPFGs), and lead-out SMF, with tapered air cavity (TAC) connecting SMF The transmissive characteristics without are analyzed theoretically experimentally. Mode coupling CLPFGs at longer wavelength could be enhanced, as well the sensing performance increases times over gratings. refractive index (RI) sensitivity can...

We present a refractometer with main-and vernier-scale to measure the refractive index (RI) of liquids high precision by using fine spectrum structure tilted fiber Bragg grating (TFBG).The absolute RI values are determined accurate wavelength cut-off mode resonances.The calibrated measuring large groups spectra at different resonances in small range, and use certainly reduces measurement uncertainty resulted from discrete cladding performance TFBG-based vernier is experimentally verified...

We have demonstrated an ultra-broadband fiber mode converter based on CO2-laser inscribed length apodized phase-shifted long-period gratings (LPGs) with a three-section linear apodization profile, where π-phase shift was introduced between two adjacent grating sections. The parameters were optimized theoretically to achieve the broadband conversion LP01 and LP11 mode. device provides efficiency higher than 90% over ultra- broad bandwidth of ∼182nm. insertion loss LPGs is negligible. Orbital...

We report a simple method for generating optical vortex beams (OVB) from an all-fiber laser. An intracavity mode converter based on few-mode fiber long-period gratings was used to enable the OVB operation. The intensity profiles and wavefront helicity of output laser were characterized by analyzing spatial emission its self-interference. Selection handedness can be achieved simply adjusting polarization controller. ~50 mW power both first-order second-order modes generation with...

Wavelet analysis of NASA scatterometer (NSCAT) backscatter and DMSP special sensor microwave imager (SSM/I) radiance data can be used to obtain daily sea ice drift information for the Arctic region. This technique provides improved spatial coverage over existing array Ocean buoys better temporal resolution techniques utilizing from satellite synthetic aperture radars. Comparisons with motion derived ocean give good quantitative agreement. Both comparison results NSCAT SSM/I are compatible,...

A magnetic field sensor using fiber ring cavity laser based on fluid (MF) is proposed and experimentally demonstrated. MF-coated single-mode-no-core-singlemode structure inserted in the cavity, which acts as a bandpass filter sensing component simultaneously. The excellent filtering with high side-mode suppression ratio (14 dB) small insert loss of around (-1.03 caused by self-imaging effect. experimental results show that lasing wavelength shifts to blue side increase external field....

We demonstrate the multiparametric monitoring of directional bending, torsion, and temperature based on helical long-period gratings (HLPGs) in a triangular four-core fiber (FCF) using CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser irradiation. The simulations investigated stress-relaxing effect stress-applying parts due to heating. In experiments, HLPGs with period 435 μm number 60 induced FCF have been for monitoring. bending...

Arctic sea ice motion for the period from October 1999 to March 2000 derived QuikSCAT and ocean buoy observations.Special Sensor Microwave/Imager (SSM/I) data using wavelet analysis method agrees well with observations. Results SSM/I are compatible when compared observations complement each other. Sea drift merged daily results QuikSCAT, SSM/I, gives more complete coverage of motion. Based on six months maps, maps in appear have smoother (less noisy) patterns than those NSCAT, especially...

In this paper, we present a method of velocity measurement using novel self-mixing velocimeter with orthogonal-beam incident system (OSMV), which enables the without knowing angle information. The fiber ring laser used could provide stable and narrow-width light source, enhance stability signal-to-noise ratio velocimeter. result indicates much better linearity our than traditional one in turntable experiment due to use source. relative error rates are up 1.258% contrast 13.720% one.

In this Letter, we propose a multi-channel mode converter with the concept of modal interferometer in two-mode fiber (TMF). Two lateral stress points TMF function as in-line couplers to construct interferometer, and both transmission spectra near-field patterns confirm that LP01 is successfully converted into an LP11 at multiple channels. The measured conversion efficiency almost completely follows theoretical tendency. Finally, realized 20 channels C+L wavelength band up 99.5% insertion...