Modulation response of laser for small-signal modulation

Question

Answer the following questions in detail.

Question 1) Derive an expression for numerical aperture in a step-index fiber. Sketch the intensity pattern for LP₁₂ mode.

Question 2) Explain mode control in tunable lasers.

Question 3) Calculate the responsivity of an InGaAs APD operating at 1.55 (μm and having a quantum efficiency of 0.7 if its gain is 10. How much optical power is needed by this detector to produce 20 nA?

Question 4) Explain these in derail: timing jitter, RIN and inter channel crosstalk.

Question 5) Write a detailed note on code division multiplexing.

Question 6) Describe the different sources those contribute to power penalty in optical links.

Question 7) Explain the modulation response of laser for small-signal modulation.

Question 8) Derive an expression for signal-to-noise ratio in APDs.