The correct answer is: B. Wavelength shifting.
Self-phase modulation (SPM) is a nonlinear optical effect in which the refractive index of a material is modulated by the intensity of light propagating through it. This modulation can cause the light to shift in wavelength, a phenomenon known as wavelength shifting.
SPM can be used for a variety of applications, including optical communications, optical sensing, and optical metrology. In optical communications, SPM can be used to generate optical solitons, which are pulses of light that are resistant to dispersion and can propagate over long distances without distortion. In optical sensing, SPM can be used to detect changes in the refractive index of a material, which can be used to measure temperature, pressure, and other physical properties. In optical metrology, SPM can be used to measure the length of a fiber optic cable or the distance between two objects.
The other options are incorrect because:
- Option A is incorrect because SPM does not affect the core diameter of a fiber optic cable.
- Option C is incorrect because SPM does not decrease the attenuation of light in a fiber optic cable.
- Option D is incorrect because SPM does not reduce the losses in a fiber optic cable.