We have analyzed the effects of the fiber cladding radius on the characteristics of long-period fiber gratings. By etching the cladding of a common single-mode fiber, we verified the characteristics experimentally. When by etching we reduce the cladding radius of a common single-mode fiber on which a long-period refractive-index modulation has been imposed, the coupling strength of the core and the cladding modes increases. In addition, the difference in the propagation constants (for a fixed wavelength) between the core mode and the cladding modes increases; hence the resonant transmission dip wavelengths shift to longer wavelengths. The proposed method can be useful in making and detuning long-period fiber grating filters.
© 2000 Optical Society of America
Sungchul Kim, Yoonchan Jeong, Seungwoo Kim, Jaejoong Kwon, Namki Park, and Byoungho Lee, "Control of the Characteristics of a Long-Period Grating by Cladding Etching," Appl. Opt. 39, 2038-2042 (2000)