Abstract

Radiation loss characteristics are calculated for the first two LP modes of a double-clad lightguide structure in which the inner cladding forms a low refractive-index well between the core and the outer cladding. The higher-order mode is defined to be effectively cut off at wavelengths where the LP(11) mode power is sufficiently attenuated to ensure negligible modal noise due to interference between LP(01) and LP(11) modes. Calculations apply for various deposited cladding thicknesses and findings can be easily extrapolated if specifications are changed for system requirements on the minimum unspliced fiber length or the extinction ratio between P(11) and P(01) mode powers, Re = 10 log P(11)/P(01). The latter is specified at points such as splice joints where modal noise is generated. Theoretical results are correlated with measurements in order to determine the effective cutoff wavelength for fibers in which leaky-mode loss mechanisms dominate. The procedure should be extremely useful for determining the shortest usable wavelength for single-mode lightwave systems.

© 1985 Optical Society of America

Bending loss of propagation modes in arbitrary-index profile optical fibers

Jun-ichi Sakai and Tatsuya Kimura
Appl. Opt. 17(10) 1499-1506 (1978)

Measuring cutoff wavelength of HE₂₁, TE₀₁, and TM₀₁ modes: a novel method using single-polarization launching

Yasuyuki Kato and Mitsuru Miyauchi
Appl. Opt. 24(15) 2351-2354 (1985)

Comparison of cutoff wavelength measurements for single-mode waveguides

C. C. Wang, C. A. Villarruel, and W. K. Burns
Appl. Opt. 22(7) 985-990 (1983)

Ultrashort-pulse investigation of the propagation properties of the LP₁₁ mode in 1.55-μm communication fibers

Ilaria Cristiani, Luca Tartara, Gian Piero Banfi, and Vittorio Degiorgio
Opt. Lett. 26(22) 1758-1760 (2001)

Effect of periodic strain on the leaky modes in single-mode fiber

H. Grebel and M. Mezhoudi
Appl. Opt. 27(23) 4819-4821 (1988)