这是一篇来自英国的关于激光基础知识和soa的作业代写

Answer all questions.

1. Derive an expression for the frequency and wavelength spacing between the longitudinal modes of a Fabry-Perot laser. Explain why the Fabry-Perot spacing is constant in frequency but varies with wavelength.
2. With the aid of suitable diagrams, indicate the type of lateral waveguiding used in:
   1. stripe waveguide laser
   2. ridge waveguide laser
   3. buried waveguide laser

With reference to the diagrams above, discuss the current confinement performance in each structure.

3. Describe the self saturation process which limits the gain of a high gain SOA.q If I connect 2 high gain(30dB) SOA devices in series, estimate the gain of the system. What optical component could I place between them to increase the gain of the system?
4. Plot the carrier lifetime versus carrier density for a SOA with A= 1×10⁸s^-1B= 3×10-¹⁰cm³s^-1 and C=2×10^-28 cm⁶ s^-1. Indicate the regions on the curve where each of the A, B and C coefficients dominate the value of carrier lifetime.