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Lasers all have some light-emitting material sandwiched between two mirrors; the

ID: 2094760 • Letter: L

Question

Lasers all have some light-emitting material sandwiched between two mirrors; the "exit" mirror often reflects 95% of the light that hits it, sending it to the measuring mirror (on the left in the diagram). In order to "lase", the light must travel an integer number of wavelengths during the round-trip from exit mirror to left mirror and return to exit mirror. The mirrors in our Diode lasers are 0.193 [mm] apart, and the diode material's refractive index (between the mirrors) is 1.630 at the diode wavelength 650.0 [nm] .

How many wavelengths "fit" in that round-trip path length? ... what wavelength would have 1 less wave than this number fitting between the mirrors?

968 ... 649.0 [nm]

364 ... 652.3 [nm]

182 ... 647 [nm]

484 ... 651.3 [nm]

484 ... 648.6 [nm]

968 ... 650.6 [nm]

182 ... 654.2 [nm]

968 ... 649.3 [nm]

364 ... 648.8 [nm]

968 ... 649.0 [nm]

364 ... 652.3 [nm]

182 ... 647 [nm]

484 ... 651.3 [nm]

484 ... 648.6 [nm]

968 ... 650.6 [nm]

182 ... 654.2 [nm]

968 ... 649.3 [nm]

364 ... 648.8 [nm]

Explanation / Answer

484 ... 651.3 [nm]


a) n*t/lambda=484

b) n*t/483=651.3 nm