Radiative losses in single-mode fiber waveguides with a depressed cladding

A comparison was made of the calculated and measured radiative losses suffered by the fundamental and first higher modes in real waveguide structures with a depressed cladding. It was found that in determination of the operating range of single-mode waveguides with a depressed cladding it is essential to allow not only for the increase in the losses due to leaking of the fundamental HE₁₁ mode at long wavelengths, but also for the shift of the cutoff wavelength of the first higher HE₂₁ mode for shorter wavelengths.