A 60.0 -m W pulsed laser produces a pulse of EM radia tion...

A 60.0 -m $\mathrm{W}$ pulsed laser produces a pulse of EM radia tion with wavelength $1060 \mathrm{nm}$ (in air) that lasts for 20.0 ps (picoseconds). (a) In what part of the EM spectrum is this pulse? (b) How long (in centimeters) is : single pulse in air? (c) How long is it in water $(n=1.33) \equiv$ (d) How many wavelengths fit in one pulse? (e) What is the total electromagnetic energy in one pulse?

A 60.0 -m $\mathrm{W}$ pulsed laser produces a pulse of EM radia tion with wavelength $1060 \mathrm{nm}$ (in air) that lasts for 20.0 ps (picoseconds). (a) In what part of the EM spectrum is this pulse? (b) How long (in centimeters) is :
single pulse in air? (c) How long is it in water $(n=1.33) \equiv$
(d) How many wavelengths fit in one pulse? (e) What is the total electromagnetic energy in one pulse?

Key Concepts

Wavelength and Pulse Cycles

This relates to determining how many complete wavelengths (or cycles) fit into the spatial length of a pulse. By dividing the pulse's spatial extent by the wavelength in that medium, one can assess the number of oscillations present, which is important in understanding coherence and phase relationships.

Energy Calculation from Power and Time

Electromagnetic pulse energy is calculated by multiplying the power of the radiation by the duration of the pulse. This concept links the continuous measurement of power to the discrete energy delivered in pulses and is fundamental in energy quantification in pulsed systems.

Refractive Index

The refractive index of a medium quantifies how much light slows down compared to its speed in a vacuum. It is crucial for calculating the adjusted speed of light in different materials, which in turn affects the spatial length of pulses travelling in those materials.

Pulse Duration and Spatial Extent

Pulse duration is the time over which a pulse occurs and, when multiplied by the speed of light, gives the spatial length of the pulse in a given medium. This relationship allows one to find the distance the pulse occupies, connecting temporal characteristics with spatial dimensions.

Electromagnetic Spectrum

This concept covers the classification of electromagnetic radiation based on its wavelength or frequency. Knowing which part of the spectrum a given wavelength falls into (e.g., ultraviolet, visible, infrared) is key to understanding the behavior and applications of that radiation.

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