Fabrication and characterisation of long, narrowband fibre gratingsby phase mask scanning

Fibre Bragg gratings up to 50 mm in length have been fabricated using a phase mask scanning technique. Reflectivities of up to 70% and linewidths as narrow as 0.029 nm have been measured. The fabrication technique lends itself to writing gratings with controllable length, chirp and shading     

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     

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。     

Narrow line semiconductor laser using fibre grating

A narrow linewidth, low chirp, wavelength selectable, packaged alternative to current DFB structures has been developed which employs a fibre reflection grating incorporated in the fibre pigtail. The wavelength of the packaged device can be determined by the appropriate choice of fibre grating coupled to the antireflection coated facet of a 1.55 mu m BH laser. Linewidths of less than 50 kHz, sidemode suppression of more than 30 dB and chirp when modulated at 1.2 Gbit/s of <0.5 MHz have been demonstrated.<>     

紫外写入光纤Bragg光栅及其发展

把要评述了光纤光栅的理论背景、光纤的光敏性，对至今发展起来的几种主要光纤光栅紫外写入技术和chirp光栅生成技术进行了全面的评介，最后介绍了光纤光栅在激光和通信方面的一些重要应用。     

Photosensitivity in low-loss perfluoropolymer (CYTOP) fibrematerial

Photosensitivity in a perfluoropolymer (CYTOP) optical fibre is investigated. Significant diffraction has been observed from transmission gratings made from the fibre. A maximum diffraction efficiency of 1.6% has been achieved, corresponding to an index change ≃3×10^-4. The study demonstrates for the first time the existence of significant photosensitivity and the feasibility of writing a Bragg grating in a CYTOP fibre     

High-temperature stability of long-period fiber gratings producedusing an electric arc

We report, for the first time to our knowledge, the excellent optical performance of long-period gratings written in three standard fibers and in two nonstandard fibers, namely, S-doped and N-doped fibers, using the flexible and low-cost electric arc technique. The fundamental mechanism for their formation is proposed. The grating thermal behavior and the effect of fiber preannealing prior to writing have been investigated. We have demonstrated a good stability of these gratings at high temperatures     

Millimetre-wave optical beamforming network for phased-arrayantennas employing optical upconversion and wideband chirped fibregratings

A novel optical beamforming architecture for phased-array antennas operating at millimetre-wave frequencies is presented. Experimental results at 28 GHz have demonstrated the very good performance of this technique, based on optical upconversion and wideband chirped fibre gratings     

A writing technique for long fiber Bragg gratings with complexreflectivity profiles

We have developed and demonstrated a novel technique to manufacture very long gratings with a nearly arbitrary reflectivity profile. The technique is based upon writing a set of consecutive subgratings with interferometric control of the relative position of each subgrating     

Fabrication of single-polarisation single-mode-fibre couplers

Fused biconical taper fibre couplers have been fabricated from single-polarisation single-mode fibres. A CVD technique is applied to permit maintenance of parallel alignment of the fibres in the coupler fabrication process. The couplers can hold linear polarisation along the principal axis of the fibre branches, showing an extinction ratio of about ?15dB.     

Photonic Generation of Chirped Microwave Pulses Using Superimposed Chirped Fiber Bragg Gratings

A novel approach to generating linearly chirped microwave pulses in the optical domain based on spectral shaping and linear frequency-to-time mapping is proposed and experimentally demonstrated. In the proposed system, the spectrum of a femtosecond pulse generated by a mode-locked fiber laser is spectrum-shaped by an optical filter that consists of two superimposed chirped fiber Bragg gratings (SI-CFBGs) with different chirp rates. The SI-CFBGs form a Fabry-Perot cavity with a cavity length linearly dependent on the resonance wavelength, thus a spectral response with an increased or decreased free spectral range is generated. A chirped microwave pulse with the pulse shape identical to the shaped spectrum is obtained at the output of a high-speed photodetector thanks to the frequency-to-time mapping in a dispersive device. The proposed technique is experimentally demonstrated, a linearly chirped microwave pulse with a central frequency of 15 GHz and a chirp rate of 0.0217 GHz/ps is experimentally generated.     

Optical cross-connect structures for interleaved multiwavelengthbidirectional ring networks

Novel bidirectional optical cross-connect structures using a single arrayed waveguide grating router and tunable fibre Bragg gratings have been proposed for interleaved multiwavelength ring networks. In the proposed structures, each wavelength channel is independently switched by tuning the centre wavelength of the gratings. The feasibility of the cross-connectors has been experimentally demonstrated. A homodyne crosstalk less than -26 dB and a backscattering suppression ratio of -35 dB have been obtained     

线性啁啾型光纤光栅双稳特性的理论研究

基于非线性耦合模理论,利用逆向递推传输矩阵方法,数值研究分析了线性啁啾型光纤光栅（LC-NLBG）的双稳开关性能。研究结果表明：在NLBG中引入啁啾能扩大实现双稳的入射光波长范围,当光栅啁啾参量发生变化时,光栅双稳开关性能表现出明显的差异,此差异源于啁啾光栅内部前向波能量分布的不同。     

相位掩模法制造光纤光栅的理论分析

推导出了用相位掩模法制造光纤光栅的理论根据，得出相位掩模法中常见的一些有用公式，并报道了实验结果。     

Fabrication of periodic domain grating in LiNbO/sub 3/ by electron beam writing for application of nonlinear optical processes

A novel technique for the fabrication of domain reversed gratings in LiNbO/sub 3/ by means of direct electron beam writing at room temperature without any static bias is reported. The domain grating has been achieved not only at the -c surface of the crystal, but also for the entire region of the crystal. Such a structure should be useful for various nonlinear optic applications. A preliminary study on the second harmonic generation has also been demonstrated under the quasi-phase matched condition with high efficiency.<>     

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     

Fibre-polarimeter based on grating taps

The fabrication of novel tilted fibre Bragg gratings coupling light out of the fibre core into two different directions is demonstrated. These gratings in combination with a fibre based quarter waveplate are used to form a high-speed fibre polarimeter for real-time polarisation monitoring.