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e894a3h - 4 If the spot radius is 1.5 mm for a HeNe TEM 00...

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ENSC 460/894 Assignment 3: (Feb. 24, 2005 due Mar. 3, 2005) 1 With reference to the Nd:Yag energy level diagram from the notes estimate the maximum possible efficiency of an Nd:Yag laser. Take the efficiency to given by the ratio of optical output power to input pumping power. (5 marks) 2 A pulsed Nd:Yag flashlamp pumped laser operates using a 100 µ F capacitor charged up to 2 KV for each pulse. The laser emits an approximately triangular pulse (see diagram in notes) of duration 1 msec and peak power 1 kW. Calculate the overall efficiency of the laser (assuming the Capacitor charging to be 100% efficient). 3 Calculate the approximate peak wavelengths from expected from the following materials given their bandgaps: GaAs (1.44 eV), GaP (2.26 eV) CdTe (1.50 eV), InP (1.35 ev), SiC (3.00 eV)
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Unformatted text preview: 4. If the spot radius is 1.5 mm for a HeNe TEM 00 mode beam entering a lens of f=12.5 cm 3(a) Calculate the focused spot size.(3 marks) 3(b) Calculate the depth of focus to keep the spot size within 10% of the minimum value.(4 marks) 5 For a GaAs laser diode the laser emission area is 1 micron thick by 50 microns wide. Calculate the divergence angle in the vertical and horizontal direction. What is the Rayleigh range for each direction, (8 marks) 6 Assume a single layer antireflection coating is to be deposited on long IR ZnSe lens (n=2.4) for a wavelength of a CO 2 laser (10.4 microns). (a) What is the minimum thickness for this coating (3 marks) (b) What is the next smallest thickness that will give an AR coating. (2 marks)...
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