We demonstrated a wavelength scanning time division multiplexing of 1000 ultra-weak fiber Bragg gratings (FBG) for distributed temperature sensing. The strong multiplexing capability and low crosstalk of the ultra-weak FBG sensors is investigated through both theoretical analysis and experiment. An automated FBG fabrication system was developed for fast 1000-FBG fabrication. The measurement accuracy of Bragg wavelengths for more than 80% FBGs is less than 20 pm, corresponding to 2 $^{\circ}$ C in temperature.

A Large Serial Time-Division Multiplexed Fiber Bragg Grating Sensor Network

Continuous-wave silica-based erbium-doped fibre lasers

Self-stabilizing effect of four-wave mixing (FWM) is analyzed and proven in this letter by using the undepleted approximation and the perturbation method. Multiwavelength erbium-doped fiber lasers with excellent stability and uniformity are demonstrated experimentally at room temperature. The novel fiber lasers are stabilized and equalized as a result of the balance between the self-stabilizing function of FWM and the mode competition effect of erbium-doped fiber.

Self-stabilizing effect of four-wave mixing and its applications on multiwavelength erbium-doped fiber lasers

A strain and temperature-sensing scheme based on a dual-wavelength fiber laser is demonstrated experimentally By measuring the change in the wavelength separation of the two lasing wavelengths and the shift of any of two lasing wavelengths, the measured strain and temperature are very linear and have a strain sensitivity of 015 pm/muepsiv over a range of 0-2400 muepsiv and a temperature sensitivity of 143 pm/degC over a range of 22degC-230degC, respectively

A Dual-Wavelength Fiber Laser Sensor System for Measurement of Temperature and Strain

We propose a novel fiber Bragg grating (FBG) sensor system using a linear-cavity fiber laser scheme with a distributed Raman amplifier as a gain medium. The inhomogeneous broadening property of the distributed Raman amplifier is used for multiwavelength operation. The experiment shows that such a linear-cavity fiber Raman laser can provide a stable output with an optical signal-to-noise ratio over 50 dB even if the FBG is located at a 25-km remote sensing position. The feature of our proposed fiber laser can facilitate a long-distance or a large-scale fiber sensor system and can be easily extended for multipoint sensing applications.

https://ir.nctu.edu.tw:443/bitstream/11536/27082/1/000189020000075.pdf

Long-distance FBG sensor system using a linear-cavity fiber Raman laser scheme

A wavelength-division-multiplexing technique for interrogating 10-cascaded fiber Bragg grating sensing elements based on a ring-compounded-cavity fiber laser is reported. A feedback control technique was introduced to a tunable Fabry-Perot filter that tracks the wavelength-shift of the sensor. The sensors were demodulated using an unbalanced scanning Michelson interferometer and a sensitivity of 1.682/spl deg///spl mu//spl epsi/ has been demonstrated.

Fiber-laser-based wavelength-division multiplexed fiber Bragg grating sensor system

An all-optical polarizer, which can repolarize a highspeed data signal without converting the state-of-polarization variations into amplitude jitters, is realized using a mutual injection-locked laser diode. The all-optical polarizer is used to simultaneously realign the state-of-polarizations of two 10-Gb/s polarization-scrambled nonreturn to zero signals without state-of-polarization characterization and feedback control.

/pdf/simultaneous-repolarization-of-two-10-gb-s-polarization-4r6e9odv47.pdf

Simultaneous repolarization of two 10-Gb/s polarization-scrambled wavelength channels using a mutual-injection-locked laser diode

All-optical waveform reshaping of a distorted 10-Gb/s nonreturn-to-zero (NRZ) pseudorandom bit sequence (PRBS) signal using two-mode injection locking in Fabry-Perot laser diode (FP-LD) was demonstrated. Simultaneous waveform reshaping of two 10-Gb/s distorted NRZ PRBS signals using a single FP-LD was also demonstrated.

/pdf/simultaneous-all-optical-waveform-reshaping-of-two-10-gb-s-2mkq7c57ru.pdf

Simultaneous all-optical waveform reshaping of two 10-Gb/s signals using a single injection-locked Fabry-Perot laser diode

A wavelength-switchable La-codoped bismuth-based erbium-doped fiber ring laser with the capability to switch to one of 35 lasing wavelengths, spaced at 0.8 nm from 1545 to 1575 nm, is reported. Excellent wavelength stability of better than 1 pm and power fluctuation of less than 0.15 dB were observed during a 2-h stability test.

Wavelength-switchable La-codoped bismuth-based erbium-doped fiber ring laser

A low beat-noise highly polarized tunable fiber ring laser is proposed and experimentally demonstrated by using a Fabry-Pe/spl acute/rot laser diode (FP-LD), which acts as a high-pass filter to suppress both the beat noise and TM-polarized light. The wavelength of the fiber ring lasers can be tuned from 1536.82 to 1570.72 nm in 1.12-nm steps and its maximum output power is about +3 dBm. The degree of polarization and extinction ratio of the laser output are about 99% and 60 dB, respectively. The beat-noise with and without the FP-LD was reduced dramatically by 50 dB.

/pdf/low-beat-noise-polarized-tunable-fiber-ring-laser-3j1g8i7s7j.pdf

W.H. Chung

Papers

Fiber-laser-based wavelength-division multiplexed fiber Bragg grating sensor system

Simultaneous repolarization of two 10-Gb/s polarization-scrambled wavelength channels using a mutual-injection-locked laser diode

Simultaneous all-optical waveform reshaping of two 10-Gb/s signals using a single injection-locked Fabry-Perot laser diode

Wavelength-switchable La-codoped bismuth-based erbium-doped fiber ring laser

Low beat-noise polarized tunable fiber ring laser