长周期莫尔光栅的理论研究

长周期光纤光栅作为一种损耗型的带阻滤波器，在光纤通信和光纤传感器领域有着广泛的应用。结合长周期光纤光栅的传输特性，利用传输矩阵法对多种长周期莫尔光栅的透射谱进行了理论模拟。分析结果表明，莫尔光栅技术在制作高性能的相移长周期光栅和变迹长周期光栅上有着很好的应用前景。     

Ultra-High Temperature Gratings

Regenerated gratings seeded by type-I gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other gratings. These ultra-high temperature （UHT） gratings extend the applicability of silicate based components to high temperature applications such as monitoring of smelters and vehicle and aircraft engines to high power fibre lasers.     

Moving fibre/phase mask-scanning beam technique for enhancedflexibility in producing fibre gratings with uniform phase mask

A new and flexible technique for producing photorefractive fibre gratings with a uniform phase mask is demonstrated. By slowly moving the fibre relative to the mask as the writing beam is scanned, wavelength shifts, pure apodisation and phase-shifted gratings can be achieved     

Mode coupling in spiral fibre gratings

The coupling properties of spiral fibre gratings are presented. It is shown that LP₀₁ modes in spiral fibre gratings couple to both LP₁₁ even and odd modes     

Dual wavelength fibre interferometer with wavelength selection via fibre Bragg grating elements

The use of intra-core fibre gratings to provide the selection of two stable, closely spaced wavelength-components at the output of a fibre interferometer is reported. An unambiguous sensing range in the optical path difference of an interferometer of +or-0.49 mm is demonstrated using two gratings spaced by 2.5 nm.<>     

Bend measurement using Bragg gratings in multicore fibre

The first measurements of curvature made using Bragg gratings written in separate cores of a multicore optical fibre are described. The gratings act as independent, but isothermal, strain gauges. The difference in Bragg wavelength between the gratings provides a temperature-independent measurement of the local curvature     

Optical comb filter based on spectral talbot effect in uniform fibre bragg gratings

A comb optical filter based on the spectral Talbot effect in uniform low reflecting fibre Bragg gratings is numerically and experimentally demonstrated, relaxing the need for any chirp or equivalent phase shifts between the gratings. It can be understood by the analogy between the compression and rate multiplication of phase modulated pulse trains and sampled fibre Bragg grating spectrum formation     

啁啾光纤光栅的色散补偿及其理论极限分析

我们给出了一个描述光纤光栅进行色散补偿的模型,另外,还对啁啾光纤光栅补偿能力的理论极限进行了分析。     

Strong asymmetric stresses arc-induced in pre-annealed nitrogen-doped fibres

Long-period gratings were written using arc discharges in pristine nitrogen doped fibres. Comparison of the resulting gratings spectra show that the resonant positions of gratings in fibres pre-annealed at 1050/spl deg/C for 30 min are shifted towards shorter wavelengths and their coupling strength is considerably higher. The refractive index and residual stress profiles were measured before and after annealing, as well as the two-dimensional stress profiles inside the grating region. Arc discharges induce periodic and strong asymmetric stresses in the fibre core of the pre-annealed nitrogen doped fibre.     

Fabrication of chirped fibre gratings using etched tapers

A technique for fabricating fibre gratings with an accurately controlled chirp profile is demonstrated. The technique involves writing a grating over a section of fibre, the cladding of which has been tapered by etching it in HF acid. A strain gradient along the taper is used to produce the chirp either during or after writing. Linearly chirped gratings with bandwidths up to 4.8 nm have been demonstrated. Transmission filters have also been demonstrated when a step is made in the taper     

Dual-wavelength cascaded Raman fibre laser

Dual-wavelength lasing at 1480 and 1500 nm has been demonstrated from a cascaded Raman fibre laser with a WDM coupler and two pairs of Bragg gratings. Intensity-adjustable, wavelength-tunable laser operation was achieved by tensile stress wavelength tuning of the gratings     

Multi-wavelength, continuous wave fibre Raman ring laser operatingat 1.55 μm

A four wavelength continuous wave, fibre Raman ring laser has been demonstrated at room temperature using fibre Bragg gratings as the wavelength-selective elements with applications as a multi-wavelength source for optical fibre telecommunications. Channel spacings were ~5 nm between 1551.6 and 1565.1 nm with 14.9 dBm total output power     

Annealing of arc-induced gratings at high temperatures

Long period gratings arc-induced in different types of fibre were annealed at 1000degC for 24degh. During the annealing, the spectrum of the gratings written in Ge-doped fibres shifted towards longer wavelengths whereas an opposite shift was observed for gratings written in Ge-free fibres. A discussion on the mechanisms responsible for that behaviour is presented.     

Annealing time dependence at very high temperature of electricarc-induced long-period fibre gratings

Long-period fibre gratings fabricated with an electric arc have been annealed at high temperatures. The time dependence of transmitted spectra are reported and related to the evolution of internal stresses in the fibre     

光纤光栅反射特性及相位掩模法制作的理论分析

在对光纤光栅折射率分布进行合理假设的基础上，运用耦理论计算了光纤光栅的反射特性，对其反射特性与相关参数的关系进行了进行了分析。