Problem 1 (30 points) (a) (10 points) What are the basic com…
Questions
Prоblem 1 (30 pоints) (а) (10 pоints) Whаt аre the basic components that are necessary to make a laser? Describe briefly the function of each component listed. (b) (5 points) Should you expect gas lasers at relatively low pressure to have emission spectral lineshapes that are dominated by homogeneous broadening or inhomogeneous (i.e. Doppler) broadening? Explain your reasoning. (c) (15 points) Q-switching (i) Qualitatively describe Q-switching and how it is used in laser systems. (ii) What are two methods of accomplishing Q-switching? (iii) What are typical pulse duration and peak power values for Q-switched lasers? Problem 2 (30 points) The L-Shaped Cavity of a Nd:YVO4 laser is shown below. Answer the following questions. Assume the cavity(except the Nd:YVO4 crystal) is filled with air. (a) (10 points) Calculate the free spectral range(FSRυ) for the cavity in MHz. (b) (5 points) For a light source at 532 nm what is the spacing (FSRλ , in terms of wavelength) between the longitudinal modes? (c) (5 points) What is the Finesse of the cavity? (d) (10 points) The gain medium above can be described by a four level system shown below. Sketch the approximate population densities (N2 and N1) for the given lifetime ratios and pump intensities. Provide a brief explanation explaining solution. You may sketch and label the population densities on the plot provided for each case. Initial population of states 1 and 2 can be assumed to be 0. State any additional assumptions you make, if required. Problem 3 (40 points) In the laser system shown below, only state 2 is pumped directly from the ground (or 0) state with a pumping value of R2 (cm-3/sec). State 2 decays to 0 at a rate of 5 x 106 sec-1 and to 1 by spontaneous emission (A21) and quenching collisions (k21) at a total rate (A21+k21) of 107 sec-1. The lifetime (τ1) of state 1 is 50ns. Assume homogeneous broadening; line width Δυ = 2 cm-1(= 60 GHz), λ= 400 nm; A21 = 106 sec-1; M= 40 x 1.67 x 10-27 kg; T=500K and that the medium fills the cavity in the manner shown below. Also assume steady state. (a) (10 points) What is the stimulated emission cross section at line center? (b) (10 points) Estimate the population inversion necessary to bring the laser to threshold? (c) (10 points) Write down the rate equations for the system described and calculate the steady state population densities N2 and N1. (d) (10 points) What is the pump rate needed to bring the laser to threshold? (Hint: gi=2Ji+1) Congratulations, you are almost done with this exam. DO NOT end the Honorlock session until you have submitted your work. 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 as follows: Email your PDF to yourself or save it to the cloud (Google Drive, etc.). Click this link to go to Gradescope: Final Exam Return to this window and click the button below to agree to the honor statement. Click Submit Quiz to end the exam. End the Honorlock session.
Which оf the fоllоwing stаtements regаrding GDP is correct? 1. GDP includes fаctory production, but not any harm that may be inflicted on the environment. 2. GDP accounts for all activities taking place outside markets. 3. GDP is a good measure of economic well-being for all purposes. 4. GDP provides detailed information about the distribution of income.