What are the losses in a laser cavity?

Question

I studied that to get the lasing conditions gain must overcome the losses. But what are the losses? Thanks a lot

Answer 1

The main ones are:

• Mirror losses. No mirror is 100% reflective. Even if there were, if you used 100% reflective mirrors on both ends, your laser would have no output beam.

• Scattering in the beam path, or material absorption in the beam path.

• Diffraction. The beam spreads as it travels, so there is some light that simply falls outside the area of the mirrors.

• Any light you pick off to monitor the beam strength.

Answer 2

The significant losses in laser comes from

• the reflection loss of the grating (wavelength selective);
• resonance losses between R1 and R2;
• material attenuation and
• nonradiative combinations