Effect of Linewidth Enhancement Factor on the Second Harmonic Distortion of a Directly Modulated and Injected Fabry-Perot Semiconductor Laser

The present paper describes novel analytical results on output second harmonic (2H) modulation distortion of an optically injected Fabry-Perot laser diode which is directly modulated by a 2H-contaminated radio frequency (RF) signal. It has been found that the larger the value of linewidth enhancement factor (LEF), the lesser is the tendency of output 2H modulation distortion to fall. For a non-zero value of LEF, the 2H distortion (2HD) tends to increase first with modulation frequency and finally falls off at higher modulation frequencies. The 2HD variation curve shows a resonance-like character.