Consider an AlGaAs based heterostructure laser diode which has an optical cavity of length 200 microns. The peak radiation is at 870 nm and the refractive index of GaAs is about 3.7.
What is the mode integer m of the peak radiation and the separation between the modes of the cavity?
If the optical gain vs. wavelength characteristics has a FWHM wavelength width of about 6nm how many modes are there within this bandwidth?
How many modes are there if the cavity length is 20µm?