Fabrication and characterisation of long, narrowband fibre gratings by phase mask scanning

Rourke, H.N.; Baker, S.R.; Byron, K.C.; Baulcomb, R.S.; Ojha, S.; Clements, S.J.

doi:10.1049/el:19940852

Cited by 23 publications

(6 citation statements)

References 5 publications

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“…The bandwidth of an FBG is inversely proportional to its length, hence very long gratings with a high reflectivity are required. A number of variations of the phase-mask method based on mask scanning have been reported to achieve this goal (Martin and Ouellette 1994, Rourke et al 1994, Kashyap et al 1994. The idea is to keep the mask and the fibre held together in proximity and parallel, as shown in figure 6, except that the UV light beam is scanned along the mask and fibre assembly.…”

Section: Modified Phase-mask Methodmentioning

confidence: 99%

In-fibre Bragg grating sensors

Rao

1997

Meas. Sci. Technol.

1,324

641

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In-fibre Bragg grating (FBG) sensors are one of the most exciting developments in the field of optical fibre sensors in recent years. Compared with conventional fibre-optic sensors, FBG sensors have a number of distinguishing advantages. Significant progress has been made in applications to strain and temperature measurements. FBG sensors prove to be one of the most promising candidates for fibre-optic smart structures. This article presents a comprehensive and systematic overview of FBG sensor technology regarding many aspects including sensing principles, properties, fabrication, interrogation and multiplexing of FBG sensors. It is anticipated that FBG sensor systems will be commercialized and widely applied in practice in the near future due to the maturity of economical production of FBGs and the availability of cost effective interrogation and multiplexing techniques. Yun-JiangRao was born in Yunnan, China. He received his MEng and PhD degrees in Optoelectronics at the University of Chongqing, China, in 1986 and 1990. In 1988 he was employed as a lecturer at the University of Chongqing, where he led a research team to develop the first fully automatic single-mode fibre arc-fusion splicing machine in China. From 1991 to 1992 he worked on allfibre optically-addressed silicon microresonator sensors as a Postdoctoral Research Fellow at the University of Strathclyde in Scotland. In 1992 he joined the Department of Physics at the University of Kent at Canterbury as a Research Fellow, where he has been working on fibre-optic low coherence interferometry, development of fibre-optic pressure and temperature sensors, advanced fibre-optic sensor multiplexing techniques and in-fibre Bragg grating sensors. He has developed a universal fibre-optic point sensor system for quasi-static absolute measurements of multiparameters based on low-coherence interrogation. His current research interests are intrinsic and extrinsic singlemode fibre-based sensors, multiplexing techniques, fibreoptic interferometry and in-fibre grating sensors. He has authored or co-authored over 30 journal and 40 conference papers. * Optical power coupled into single-mode fibre.* * Tuneable wavelength range. * The spectral linewidth is, to a large degree, dependent on the grating length via an inverse relationship.

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Section: Modified Phase-mask Methodmentioning

confidence: 99%

In-fibre Bragg grating sensors

Rao

1997

Meas. Sci. Technol.

1,324

641

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“…A modification of this technique includes a transverse motion of the phase mask/fibre system (scanning mask technique [48,49]). Such an improvement allows the production of FBGs with a much longer length, significantly increasing the grating strength (reflectivity).…”

Section: Fabrication Methodsmentioning

confidence: 99%

Multi-photon high-excitation-energy approach to fibre grating inscription

Nikogosyan

2006

Meas. Sci. Technol.

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Amongst the most important and frequently used fibre devices, fibre Bragg and long-period gratings are conventionally fabricated by low-intensity (I < 107 W cm−2) UV quanta with an energy of about 5 eV, which coincides with the maximum of the absorption band of defects in germanosilicate glass (the usual material of a fibre core). Such a single-quantum photochemical technique produces refractive index changes in the fibre core and not in the fibre cladding. The use of single-quantum excitation with high-energy vacuum UV photons with 157 nm wavelength or two-quantum 193 nm excitation through the real intermediate state results in a higher excitation energy (7.9 and 12.8 eV, respectively) and significantly increases the efficiency of grating inscription. However, neither of these high-energy approaches is free of disadvantages: the 157 nm radiation is strongly absorbed by practically all optical materials and even by air; the application of the second approach is based on the existence of an intermediate state, i.e. presence of absorption at the irradiation wavelength. The new multi-photon high-excitation-energy approach to fibre grating fabrication is based on refractive index change modification by high-intensity (I ∼ 1011–1013 W cm−2) femtosecond UV, near-UV or IR laser radiation applied to fibre, which acquires a total excitation energy of about 8–12 eV via two-, three- or even five-photon (through the intermediate virtual state/states) absorption processes. Such a high value of excitation energy exceeds the band-gap energy values for both the fibre core and the cladding, which could result in asymmetric light energy deposition inside the fibre and even inside the fibre core. We will consider the advantages of this novel technique such as grating fabrication in fibres of any content, including photonic crystal ones; the writing of extremely stable gratings with erasing temperatures above 1000 °C; the point-by-point inscription of Bragg gratings, including non-uniform ‘chirped’ ones; the creation of fibre gratings with high polarization properties; etc.

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“…A modification of this technique includes a transverse motion of the phase mask/fiber system (scanning mask technique [13], [14]). Such an improvement allows the production of FBGs with greater length, significantly increasing the grating strength (reflectivity).…”

Section: Anisotropic Fbg Inscriptionmentioning

confidence: 99%