Blood disorders are diagnosed only through blood tests.

Questions

Blооd disоrders аre diаgnosed only through blood tests.

Exаm Instructiоns: Answer the questiоns belоw on the provided аnswer sheet. Follow the instructions below the exаm questions to submit your work to Gradescope. Examity must remain running until you finish submitting your work. Problems 1A - 1C: Fiber Modes (20 points) Assume one has a fiber optic cable with cladding index (n_2=1.5), core index (n_1=1.53), and core radius a=0.5 μ m {"version":"1.1","math":"(mu{m})"}. A. (10 points) Calculate the V-number of the fiber at 1.55 (mu{m}). B. (5 points) Is this fiber in the single-mode regime? Justify your answer. C. (5 points) How can one break the polarization degeneracy of this system? Problems 2A - 2B: Fiber Losses (10 points) A. (5 points) List one source of linear absorption loss in fibers. B. (5 points) List one source of nonlinear absorption loss in fibers. Problems 3A - 3B: Fiber Optic Cables (20 points) A. (10 points) What is the Numerical Aperture of an optical fiber? Describe its significance. B. (10 points) What do you understand by step-index and graded-index fibers? Problems 4A - 4B: Light Emitting Diodes (20 points) A. (10 points) Describe briefly how an LED works. B. (10 points) If one injects a current of 1 mA into an LED with 20% quantum efficiency, what photon flux will it generate? Problem 5A - 5D: Lasers (20 points) A. (10 points) What 3 fundamental processes affect the behavior of lasers, and of those, which process gives rise to lasing? B. (5 points) What is population inversion? C. (10 points) Assume one has a 2-level atom with a bandgap of 0.5 eV and a ratio of excited to ground state populations of 2. Using the Boltzmann equation, what is the effective temperature of this system? D. (5 points) What happens to a laser gain medium if it loses population inversion? Congratulations, you are almost done with Exam 1. DO NOT end the Examity session until you have submitted your work to Gradescope. When you have answered all questions: Use your smartphone to scan your answer sheet and save the scan as a PDF. Make sure your scan is clear and legible. Submit your PDF to Gradescope as follows: Email your PDF to yourself or save it to the cloud (Google Drive, etc.). Click this link to go to Gradescope: Gradescope Submit your exam to the assignment Exam 1. Return to this window and click the button below to agree to the honor statement. Click Submit Quiz to end the exam. End the Examity session.