What is the mode frequency spacing (in mHz) in a DFB laser with a guide index of 3.62 and a length of 250 μm? We wish to modulate the light output of a semiconductor laser having the optical...

What is the mode frequency spacing (in mHz) in a DFB laser with a guide

index of 3.62 and a length of 250 μm?

We wish to modulate the light output of a semiconductor laser having the optical power-current characteristic shown below by directly varying the input current. Sketch the intensity (or optical power density) waveform of the light

output for a bias current of 300 mA and an applied current signal which is

sinusoidal and has a peak to peak current variation of 200 mA.