Single Mode Fiber Bragg Grating Research Articles

Spectral investigation of multimode fiber Bragg grating based external-cavity semiconductor lasers

The output spectra of external-cavity semiconductor lasers (ECSLs) formed by using different antireflection (AR) coated laser diodes (LDs) with multimode fiber Bragg gratings (MMFBGs), are studied systematically. It is found that the side mode suppression ratio (SMSR) of the output spectra of ECSL is dependent on the relative position of the Bragg wavelength and the intracavity modes of the LD, and this effect is more apparent when the reflectivity of AR coating of LD is increased. Numerical simulations are provided to explain the experimental observations. Furthermore, the requirements of wavelength locking of ECSLs with MMFBGs are found to be different from those with single-mode fiber Bragg gratings (SMFBGs). The conditions of wavelength locking of the MMFBG-based ECSLs in terms of gain margin between the material gain peak and the gain corresponding to the selected Bragg wavelength, reflectivity of AR coating of LD and reflectivities of the Bragg wavelengths of MMFBG are comprehensively investigated, and compared with the experimental results.

Fiber Bragg-grating incorporated microbend sensor for simultaneous mechanical parameter and temperature measurement

We propose a compact microbend sensor operating in the reflection mode for simultaneous measurement of a mechanical parameter and the temperature. The sensor is composed of a single-mode fiber lead, a multimode sensing fiber, and a single-mode fiber Bragg grating, where microbending is applied to the multimode fiber for mechanical parameter measurement and the grating provides an additional signal for temperature measurement. The sensor is demonstrated experimentally with two demodulation schemes based on a broad-band source and a tunable laser, respectively. The sensor extends the capacity of a conventional microbend sensor and offers many additional advantages, including higher stability, higher sensitivity, single-end access, and superior multiplexing capability.

Demonstration of etched cladding fiber Bragg grating-based sensors with hydrogel coating

A novel hydrogel-coated single-mode fiber Bragg grating (FBG) sensor is investigated. The sensor uses a swellable polymer material, hydrogel, as the active sensing component. The sensing mechanism is based on the stress that is induced in the chemically sensitive swellable hydrogel coating. The stress shifts the Bragg wavelength of the FBG. By reducing the cladding diameter of FBG through etching with hydrofluoric acid, the tension tuning force of FBG can be lowered. Therefore, the stress induced in hydrogel can shift the wavelength of FBG more and the sensitivity of the sensor is improved. When the grating fiber is etched 37.5 μm in diameter, the sensitivity of sensor is approximately 10-fold larger than that without fiber etching.

A Theoretical Analysis of Band-edge Irregular Propagation Waves in Single-mode Fiber Bragg Gratings

Article A Theoretical Analysis of Band-edge Irregular Propagation Waves in Single-mode Fiber Bragg Gratings was published on October 1, 2003 in the journal Journal of Optical Communications (volume 24, issue 5).