Infrared lasers exist that can produce a nearly monochromatic (single-frequency) output with wavelength λ = 800 nm.
(a) Calculate the frequency of this laser output in Hz.
(b) Techniques have been developed to chop the output of such a laser into pulses lasting for times as short as a few femtoseconds (1 fs = 1 femtosecond = 1015s). If the output of the infrared laser of (a) is chopped to produce a single 20 femtosecond long pulse, how many oscillations will this wave packet contain?
(c) What, approximately, will be the frequency spread of the laser's output, in Hz? (Is this output monochromatic?)