Abstract
The noise character of semiconductor laser diodes coupled to short optical fibers is found to exhibit increased noise power peaked on the low‐frequency side of the intrinsic noise profile. The phenomenon has been observed in laser diodes with and without self‐sustained oscillations below 1.8 GHz and can be explained as a downshift in frequency of the intrinsic resonance due to the coupling of the laser cavity and the short optical fiber. This effect may introduce higher noise at frequencies where light‐wave communication systems operate even though the laser diodes themselves are very quiet.