Abstract
Two unique wavelengths (critical and cross-over) observed in the transmission spectra of fiber optic directional couplers exhibit a common (conjugate) characteristic feature, that the nature of spectral shifts flip around them. To free the transmission spectra from the opposite spectral shifts we demonstrate a judicious overlap of these wavelengths using optimized coupler parameters and dispersion management. Theoretical analysis explaining the optimization steps, dispersion management and the influence of these on the transmission and sensing properties of the considered directional coupler are presented. An ultra-high experimental refractive-index sensitivity (
$\sim$
20,550 nm/RIU) has been demonstrated by operating the directional coupler close to the critical wavelength (nearest to it largest spectral shifts are observed). This study should find applications in designing ultra sensitive refractometers which are free from critical wavelength referencing.
PDF Article
More Like This
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 Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription