We propose a Brillouin optical correlation-domain reflectometry (BOCDR), which can measure the distribution of strain and/or temperature along an fiber from single end, by detecting spontaneous scattering with controlling interference continuous lightwaves. In pulse-based conventional time-domain (BOTDR), it is difficult in principle to achieve spatial resolution less than 1 m, and measurement time as long 5-10 minutes. On contrary, continuous-wave-based BOCDR exceed limit 1-m resolution,...

This paper presents a novel method that realizes simultaneous and completely discriminative measurement of strain temperature using one piece Panda-type polarization-maintaining fibre. Two independent optical parameters in the fiber, Brillouin frequency shift birefringence, are measured by evaluating spectrum stimulated scattering (SBS) dynamic acoustic grating generated SBS to get two responses temperature. We found birefringence have same signs for strain-dependence but opposite...

For a distributed fiber-optic vibration sensor (DFVS), the signal extracted from phase of backscattering has linear response to applied vibration, and is more attractive than that intensity term. However, large noise at random weak-fading-point seriously limits sensor's credibility. In this paper, novel phase-detection DFVS developed, which effectively eliminates weak-fading-point. The relationship between analyzed, inner-pulse frequency-division method rotated-vector-sum are introduced...

Abstract The integration of high-speed optical communication and distributed sensing could bring intelligent functionalities to ubiquitous fibre networks, such as urban structure imaging, ocean seismic detection, safety monitoring underground embedded pipelines. This work demonstrates a scheme integrated in an (ISAC-OF) using the same wavelength channel for simultaneous data transmission vibration sensing. not only extends functionality system, but also improves its performance. A periodic...

Distributed strain sensing with millimeter-order spatial resolution is demonstrated in optical fibers based on Brillouin correlation domain analysis. A novel beat lock-in detection scheme introduced to suppress background noises coming from the reflection of pump waves. The frequency shifts 3 mm fiber sections are successfully measured a theoretical 1.6 mm.

We report a novel kind of all-optical dynamic grating based on Brillouin scattering in polarization maintaining fiber (PMF). A moving acoustic is generated by stimulated between writing beams one and used to reflect an orthogonally polarized reading beam at different wavelengths. The center wavelength the controllable detuning beams, 3 dB bandwidth approximately 80 MHz observed with tunable reflectance up 4% 30 m PMF.

Resonator micro optic gyro (RMOG) with a waveguide-type ring resonator is promising candidate for applications requiring small, light and robust gyros. In optical passive gyros, clockwise (CW) counter (CCW) lightwaves are phase-modulated at different frequencies to reduce the backscattering induced noise. The effectiveness of this technique, however, determined by carrier suppression level. paper, influence level on performance examined experimentally an RMOG system silica waveguide...

A novel distributed fiber vibration sensing technique based on phase extraction from time-gated digital optical frequency domain reflectometry (TGD-OFDR) which can achieve quantitative measurement with high spatial resolution and long range is proposed. 90 degree hybrid used to extract information. By increasing sweeping speed, the influence of environmental disturbance TGD-OFDR mitigated significantly, makes in our new scheme more reliable than that conventional OFDR-based method, leading...

This paper proposes a novel distributed fiber-optic acoustic sensor, which can solve both the tradeoff between maximum measurable distance and spatial resolution, that measurement vibration response bandwidth. The system is based on frequency-division-multiplexing time-gated digital optical frequency domain reflectometry, consecutively injects linear-frequency-modulated probe pulses with different ranges. Undersampling method introduced to reduce sampling rate of analog-to-digital converter...

In order to solve fading problem and realize sub-meter spatial resolution in DAS, this paper proposes a novel configuration of time-gated digital optical frequency domain reflectometry (TGD-OFDR) based on intensity modulator (IM). IM has large modulation bandwidth the positive negative harmonics can be fully used suppress while remains unchanged. experiments, with suppressed, DAS is 0.8 m strain about 245.6 pε√Hz along total 9.8-km sensing fiber. The response vibration 5 kHz, only/limited by...

Distributed fiber-optic vibration sensors based on phase-sensitive optical timedomain reflectometry (Φ-OTDR) have found many applications in various fields. In this paper, we analyze the phase noise of Φ-OTDR, which is main limiting factor measurement range. We that laser and extraction error caused by intensity photodetection contribute to total noise. By introducing a series auxiliary weak reflection points along fiber, develop phase-noise-compensated Φ-OTDR realize long-range distributed...

A novel time-gated digital optical frequency domain reflectometry (TGD-OFDR) technique with high spatial resolution over long measurement range is proposed and experimentally demonstrated. To solve the contradictory between tuning rate of lightwave frequency, which determines resolution, measurable distance in traditional OFDR, our scheme sweeps probe beam only within a time window, while local reference remains frequency-stable continuous lightwave. The frequency-to-distance mapping...

Abstract On-chip integrated mode-division multiplexing (MDM) is an emerging technique for large-capacity data communications. In the past few years, while several configurations have been developed to realize on-chip MDM circuits, their practical applications are significantly hindered by large footprint and inter-mode cross talk. Most importantly, high-speed signal transmission in arbitrarily routed circuit still absent. Herein, we demonstrate circuits based on digitized meta-structures...

Abstract The proliferation of computation-intensive technologies has led to a significant rise in the number datacenters, posing challenges for high-speed and power-efficient datacenter interconnects (DCIs). Although inter-DCIs based on intensity modulation direct detection (IM-DD) along with wavelength-division multiplexing exhibit large-capacity properties, requirement multiple laser sources leads high costs limited scalability, chromatic dispersion (CD) restricts transmission length...

Distributed discrimination of strain and temperature is demonstrated by localizing both the stimulated Brillouin scattering (SBS) dynamic acoustic grating generated in SBS process a polarization-maintaining fiber with correlation-domain continuous-wave technique. A 12- ¿¿ resolution 0.3°C together 10-cm spatial are experimentally validated.

We newly develop a temporal gating scheme to enlarge the measurement range of Brillouin optical correlation-domain reflectometry (BOCDR) for fiber-optic distributed strain measurement. In this scheme, trade-off problem between and spatial resolution can be dissolved. 66-cm 1-km were simultaneously obtained with 50-Hz sampling rate.

We theoretically and experimentally analyze the operation of Brillouin optical correlation-domain reflectometry (BOCDR). First, we confirm that BOCDR is not based on stimulated scattering but spontaneous scattering. Then, prove spatial resolution given well by same expression as analysis (BOCDA). Finally, demonstrate modulation amplitude laser frequency, which has been conventionally limited to a half frequency shift, can be enhanced further employing sensing fiber shorter than measurement range.

A kind of high-repetition-rate distributed Brillouin sensor is proposed and experimentally demonstrated based on optical correlation-domain analysis with differential frequency modulation, where the frequencies pump probe waves are modulated at slightly different RFs so that temporal position measurement continuously repeatedly swept along a fiber under test. distribution map variation 100 m acquired repetition rate 20 Hz an accuracy ±2.5 MHz spatial resolution about 80 cm.

We report on the design and characterization of ring-assisted (RA) few-mode fibers with improved minimum mode effective index difference MinΔn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> . By introducing a high-index RA structure whose position coincides trough power distribution LP xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> mode, xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> can be largely elevated while that...

Distributed fiber-optic vibration sensing based on phase extraction from optical reflectometry is discussed in this paper. The principles the coherent phase-sensitive time-domain and time-gated digital frequency-domain are introduced, experimental results of distributed measurements two techniques demonstrated. To have a better understanding performance techniques, noise process analyzed. solve problem existing measurement dead zones, influence Rayleigh fading phenomenon investigated,...

Multi-dimensional carrierless amplitude phase (CAP) modulation attracts a lot interest in recent optical communications as an advanced format with improved performance. In this paper, we have demonstrated multiband three-dimensional CAP (3D-CAP) scheme and investigated its applications short reach communication systems. Corresponding digital filters are designed by minimax algorithm additional linear constraint to avoid the coding intersymbol interference. The performance of is analyzed for...

We designed and fabricated a graded-index few-mode fiber (GI-FMF) with large effective mode area low intermodal dispersion for Raman distributed temperature sensor (RDTS) to simultaneously achieve high spatial resolution over long distance. In experiment, we measured the of RDTS using different types fibers under launch conditions based on commercially available system. By GI-FMF overfilled condition, achieved 1 °C 1.13 m at distance 25 km. The standard MMF degraded 2.58 only 0.3 higher in...

We present an ultrahigh resolution optical fiber strain sensor with a broad frequency range from quasi-static to several hundred hertz. The consists of π-phase shifted Bragg grating for sensing and Fabry-Perot interferometer as reference. laser carrier sideband are locked the reference elements, respectively, via two individual feedback loops, in which Pound-Drever-Hall technique is employed generate error signals. sampling rate up 500 samples/s demonstrational experiments, only limited by...