# How to find the FWHM-diameter of the SH beam?

#### telekom90

1. Homework Statement
Assume a Gaussian laser beam ( 1064 nm wavelength) having an FWHM-diameter(intensity) of 5 mm. By transmission through a thin nonlinear crystal, a new wave is generated that is proportional to the square of the incoming field (and therefore radiates at twice the frequency, or 532nm wavelength). This second harmonic (SH) beam co-propagates with the fundamental laser beam. What is the FWHM-diameter of the SH beam?

2. Homework Equations

dFWHM = ω(z)√2ln2

3. The Attempt at a Solution
λ =1064nm, dFWHM=5 mm$,$ λSH=532 nm .
I can't solve this problem because I don't know how to relate this equation "dFWHM=ω(z)√2ln2= 5mm " with the FWHM-diameter of second harmonic (SH) beam?!

Related Introductory Physics Homework Help News on Phys.org

#### blue_leaf77

Science Advisor
Homework Helper
The key word is
that is proportional to the square of the incoming field
.

### Want to reply to this thread?

"How to find the FWHM-diameter of the SH beam?"

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving