光纤光栅技术：基础与应用概述

5星 · 超过95%的资源需积分: 9 114 浏览量更新于2024-10-29 收藏 279KB PDF 举报

"光纤光栅技术基础与概览" 光纤光栅(fiber Bragg grating，FBG)是一种在光纤长度上周期性改变折射率的结构，它通过将光纤核心暴露于强烈的光学干涉图案下形成。该技术的历史始于1978年，由Hill等人在加拿大通信研究中心首次展示。光纤光栅的制造方法、特性以及基本属性在此被详细描述，并列举了光纤光栅技术的多种应用。一、简介光纤布拉格光栅（FBG）的形成是由于光纤轴向上周期性的折射率变化，这种变化是通过高强度的光学干涉模式诱导的。1978年的实验表明，永久性光栅可以在光纤中形成，开启了光纤光栅技术的研究。自那时起，这一技术在全球范围内得到了广泛开发，用于制造光学通信和光学传感器中的新型设备。二、光纤光栅制造技术光纤光栅的制作通常涉及紫外线光刻或直接曝光技术。紫外线光刻法利用掩模和紫外光源将光栅图案转移到光纤上；而直接曝光法则通过聚焦的激光束直接在光纤核心内产生光栅。这两种方法都依赖于光纤的光敏性，即光纤对光的敏感性，使其在特定波长下折射率发生变化。三、光纤光栅的特性光纤光栅的主要特性包括其反射特性、带宽和稳定性。布拉格反射发生在特定的波长，即满足布拉格条件的波长，当入射光的波长与光栅的周期性结构相匹配时。光栅的带宽决定了它可以反射的光谱范围，而稳定性则关系到光栅在温度、压力等环境因素变化下的性能保持。四、光纤光栅的应用 1. 光纤通信：FBG广泛用于光通信系统中的滤波器，可以有效抑制特定波长的信号，实现信道隔离，提高系统的容量和稳定性。 2. 光纤传感：利用FBG的折射率变化与物理量（如温度、压力、应变）的关系，可以构建高精度的分布式传感器网络，用于监测桥梁、石油管道、地震活动等。 3. 光谱分析：FBG可作为可调谐光谱仪的一部分，用于识别和测量不同物质的光谱特性。 4. 偏振控制：某些FBG设计可以对光的偏振态进行控制，应用于偏振分束器和偏振控制器。五、光学平面波导与组件除了在光纤中，光栅技术也应用于光学平面波导和组件，如光开关、耦合器和阵列波导光栅(AWG)。这些器件在光子集成电路和光通信网络中发挥关键作用。六、结论光纤光栅技术的发展极大地推动了光学通信和传感领域的创新。随着制造工艺的不断进步和新应用的探索，光纤光栅将继续扮演重要角色，为未来光电子技术提供更高效、更智能的解决方案。

HILL AND MELTZ: FBG TECHNOLOGY FUNDAMENTALS 1265

Fig. 2. Two-beam interferometer arrangement for side-writing ﬁber Bragg gratings (FBG’s).

enables a single irradiating excimer light pulse to photoin-

duce a large index changes in a small localized region near

the core/cladding boundary. In this case the refractive index

changes are sufﬁciently large to be observable with a phase

contrast microscope and have the appearance of damaging

physically the ﬁber. This phenomenon has been used for the

writing of gratings using a single excimer light pulse.

Another property of the photoinduced refractive index

change is anisotropy. This characteristic is most easily

observed by irradiating the ﬁber from the side with ultraviolet

light polarized perpendicular to the ﬁber axis. The anisotropy

in the photoinduced refractive index change results in the

ﬁber becoming birefringence for light propagating through the

ﬁber. The effect is useful for fabricating polarization mode

converting devices or rocking ﬁlters [13].

The physical mechanisms underlying photosensitivity are

not very well understood but are associated with the color

centers in glassy materials. For example, UV photoexcitation

of oxygen-vacancy-defect states [9] in Ge–SiO

ﬁber forms

paramagnetic GeE′ centers that contribute to the index change

[14]. There is also evidence that structural rearrangement of the

glass matrix, possibly densiﬁcation, is also correlated with the

index increase [15]. The net result of the photoinduced changes

is a permanent change in the refractive index of the glassy

material at wavelengths far removed from the wavelength of

the irradiating ultraviolet light.

IV. G

RATING FABRICATION TECHNIQUES

Historically, Bragg gratings were ﬁrst fabricated using the

internal writing [1] and the holographic technique [4]. Both

these methods, which have been described already, have been

largely superseded by the phase mask technique [16], [17]

which is illustrated in Fig. 3. The phase mask is made from

ﬂat slab of silica glass which is transparent to ultraviolet light.

On one of the ﬂat surfaces, a one dimensional periodic surface

relief structure is etched using photolithographic techniques.

The shape of the periodic pattern approximates a square wave

in proﬁle. The optical ﬁber is placed almost in contact with the

corrugations of the phase as shown in Fig. 3. Ultraviolet light

which is incident normal to the phase mask passes through

and is diffracted by the periodic corrugations of the phase

mask. Normally, most of the diffracted light is contained in

the

, 1, and 1 diffracted orders. However, the phase

mask is designed to suppress the diffraction into the zero-

order by controlling the depth of the corrugations in the phase

mask. In practice the amount of light in the zero-order can be

reduced to less than 5% with approximately 40% of the total

light intensity divided equally in the

1 orders. The two 1

diffracted order beams interfere to produce a periodic pattern

that photoimprints a corresponding grating in the optical ﬁber.

If the period of the phase mask grating is

, the period

of the photoimprinted index grating is

. Note that this

period is independent of the wavelength of ultraviolet light

irradiating the phase mask; however, the corrugation depth

required to obtain reduced zeroth-order light is a function of

the wavelength and the optical dispersion of the silica.

The phase mask technique has the advantage of greatly

simplifying the manufacturing process for Bragg gratings, yet

yielding gratings with a high performance. In comparison with

the holographic technique, the phase mask technique offers

easier alignment of the ﬁber for photoimprinting, reduced

stability requirements on the photoimprinting apparatus and

lower coherence requirements on the ultraviolet laser beam

剩余13页未读，继续阅读

bitmaster

粉丝: 0
资源: 7

光纤光栅技术：基础与应用概述

光纤光栅传感器在混凝土钢筋腐蚀检测中的应用研究

支持向量回归在长周期光栅温度应变测量中的应用

非均匀应变场下相移光栅光谱特性仿真与实验研究

Novel Bandwidth Sensor Based Fiber Grating

Incorporating a Linearly Chirped Fiber Grating

Compensating large PMD by a fiber grating

Spectral characteristics of cladding index modulated fiber grating

Fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser

Multiplexed reflective-matched optical fiber grating interrogation technique

Erbium-doped CW and Q-switched fiber ring laser with fiber grating Michelson interferometer

最新资源