7 February 2009 Sensitivity of various D-shaped fibers to external refractive index change depending on coupling strength of evanescent field
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Proceedings Volume 7212, Optical Components and Materials VI; 72120G (2009); doi: 10.1117/12.811822
Event: SPIE OPTO: Integrated Optoelectronic Devices, 2009, San Jose, California, United States
Abstract
The effect of an ambient index change on the transmission characteristics of versatile D-shaped fibers such as single mode fibers (SMFs) and photonic crystal fibers (PCFs) is investigated, which depend on the coupling strength of the evanescent field. The transmission loss of the D-shaped fibers increases as the ambient index increases because the evanescent field coupling from the core region can be enhanced by the increase of the ambient index. The coupling strength of the evanescent field can be changed by the remaining length of the cladding region in the D-shaped fiber, which can be defined as the distance between the core and the cladding. The transmission loss becomes extremely high when the ambient index is equal to the effective index of the core mode. When the ambient index is higher than that of the effective index of the core mode, the transmission loss decreases because the evanescent field is coupled back into the core region. The sensitivity of the transmission loss to the ambient index change is strongly depending on types, the remaining length of the cladding, and the polished length of fibers such as SMFs and PCFs. The remaining length of the cladding region can be determined by the coupling strength of the evanescent field.
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Hyun-Joo Kim, Oh-Jang Kwon, Young-Geun Han, "Sensitivity of various D-shaped fibers to external refractive index change depending on coupling strength of evanescent field", Proc. SPIE 7212, Optical Components and Materials VI, 72120G (7 February 2009); doi: 10.1117/12.811822; https://doi.org/10.1117/12.811822
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KEYWORDS
Cladding

Optical fibers

Polishing

Single mode fibers

Surface finishing

Refractive index

Photonic crystal fibers

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