Abstract

For what is the first time to our knowledge, we have successfully evaporated a tapered film of bromothymol blue (BTB) onto a potassium ion–exchanged (PIE) waveguide to form a composite optical waveguide (COWG) for trace-ammonia detection. The BTB film has a high refractive index (1.69) and a smooth surface and is transparent to a 633-nm laser beam in air. In the COWG structure, the BTB film serves as a single-mode waveguide, and adiabatic transition of the TE0 mode was realized between the BTB waveguide and the PIE waveguide with both BTB tapers. In the presence of ammonia, the BTB film changes color from yellow to blue, which causes absorption of the 633-nm guided wave. Our experimental results demonstrate that such a guided wave absorption–based ammonia-gas sensor is much more sensitive than one based on evanescent-wave absorption. A detection limit of part in 109 of ammonia has been realized for a BTB film–PIE glass COWG.

© 2001 Optical Society of America

Full Article  |  PDF Article

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (5)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Metrics

You do not have subscription access to this journal. Article level metrics are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription