Reference no: EM132595044

Question 1

A multimode step index fibre with a core diameter of 80 µm and a relative index difference of 1.5% is operating at a wavelength of 0.85 µm. If the core refractive index is 1.48, estimate (a) the normalised frequency for the fibre; (b) the number of guided modes.

Question 2

A single-mode fibre has an index step n₁ - n₂ = 0.005, and a core index of 1.45. Calculate the core radius if the fibre has a cutoff wavelength of 1 µm.

Question 3

A step index fiber in air has a numerical aperture of 0.16, a core refractive index of 1.45 and a core diameter of 60 µm. Determine the normalized frequency for the fiber when light at a wavelength of 0.9 µm is transmitted. Further, estimate the number of guided modes propagating in the fiber.

Question 4

An injection laser has a GaAs active region with a bandgap energy 2.3 x 10^-19 J. Estimate the wavelength of optical emission from the device and determine the linewidth in Hertz when the measured spectral width is 0.1 nm.

Question 5

A light emitting diode has a radiative recombination lifetime τ_rr of 60 ns, and a nonradiative recombination lifetime τ_nr of 100 ns.

(a) Find the internal quantum efficiency.

(b) Find the optical power that is internally generated within the device when the peak emission wavelength is 0.87 µm at a drive current of 40 mA.