ISSN:
1573-482X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Single-mode optical waveguides of 1 mm width are fabricated by thermal indiffusion so that Na+ is replaced by K+ in a simple soda-lime glass substrate. PbCl2 is selectively vacuum evaporated on to the waveguide surface as a sensitive layer (cladding). The thickness of the cladding is varied from 170 nm to 480 nm, with clad length from 2 mm to 6 mm. The prism-film coupling method with an He-Ne laser (λ = 632.8 nm) is used for characterization. The output light intensity of a TM-mode is detected by a silicon photovoltaic detector. The waveguides are tested for different gases (O2, H2, CO2, N2, Cl2, H2O), in an airtight glass chamber. The presence of only Cl2 in the surrounding air ambient reduces the output, even at a few p.p.m.. The Cl2 gas concentration is varied from 3 p.p.m. to 1.5%. There are slight changes in sensitivity with variation in the cladding thickness and length. A drastic change in sensitivity for different concentration ranges is observed as three distinct regions. The response time over a few p.p.m. to hundreds of p.p.m. is around 5 s and beyond 500 p.p.m. is around 2 s.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00188951
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