Single mode propagation

In this study we suppose nonlinear organic material shows optical Kerr effect as n = n0+n2lEl2 and n2 = X<3)/(2n0). Moreover for simplification, we suppose the waveguides allow single mode propagations and TE polarization. After appropriate handling we get the following nonlinear coupled mode equations [ 12] ... 

As the diameter and the NA decrease, so do the number of modes that can propagate down the fiber. The decrease in modes is affected more by reduction in diameter than by reduction in NA. As the diameter decreases to the wavelength of light, then only one mode will travel down the fiber. This state is referred to as single-mode propagation or a single-mode fiber. 

In this chapter, we present the fabrication parameters and optical performances of the packaged polymeric MZ waveguide modulator for photonic applications using a polymethyl methacrylate (PMMA-based side-chain polymer with 4-dimethylamino-4 -nitrostilbene (DANS). We discuss the design considerations for single-mode propagation at a wavelength of 1.3 fim in relation to the fabrication sequence. In particular, we discuss the optical power stability of our devices in detail. 

Monerie, M., Propagation in doubly clad single mode fibers, IEEE J. Quantum Electron. 1982,... 

Fig. 13.5 Calculated propagation constants (ft) for the fundamental modes of glass MNFs with refractive indices of 1.46 (silica), 1.48 (fluoride), 1.54 (phosphate), 1.89 (germinate), and 2.02 (tellurite), respectively. A circle marked on each curve corresponds to the maximum radius of the single mode MF. Radiation wavelength is X 633 nm. Reprinted from Ref. 62 with permission. 2008 Optical Society of America...

In papers , unsteady-state regime arising upon propagation of the stationary fundamental mode from linear to nonlinear section of a single-mode step-index waveguide was studied via numerical modeling. It was shown that the stationary solution to the paraxial nonlinear wave equation (2.9) at some distance from the end of a nonlinear waveguide has the form of a transversely stable distribution ( nonlinear mode ) dependent on the field intensity, with a width smaller than that of the initial linear distribution. 

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