Question

Electromagnetic Waves

In 2018, the Nobel Prize in Physics was awarded to three people, one of whom is the first woman laureate in physics in 55 years, Prof. Donna Strickland. Prof. Strickland developed the technique of chirped pulse amplification" which allows for the construction of extremely high power lasers, called pulsed lasers. These lasers are used today in many fields, including laser eye surgery. A higher power laser means that an equivalent amount of energy can be delivered in less time, resulting in more precise cuts and less thermal damage.

Consider a pulsed laser with a power of 5 W used for eye surgery with a wavelength of 193 nm (UV, which is well absorbed by tissue) and a beam width of 0.1 mm. (It could be focused even more to make a cut.) Each pulse lasts for 2 ns.

a) What is the frequency of this light? How many cycles does it go through in one pulse?

b) What is the intensity of the beam in W/m2?

c) How strong are the electric and magnetic fields?

d) How much energy is delivered by the beam over 1 pulse? What about over 1 full second (if it lasted that long)?

Answer 1