14 research outputs found
A 4 Gb/s 2-level to 2 Gsymbol/s 4-level converter GaAs IC for semiconductor optical amplifier QPSK modulators
Phase noise reduction by self-phase locking in semiconductor lasers using phase conjugate feedback
A theoretical analysis of the behavior of the frequency/phase noise of semiconductor lasers with external phase conjugate feedback is presented. It is shown that the frequency noise is drastically reduced even for lasers with butt-coupled phase conjugate mirrors. In this laser system, the phase noise takes a finite-low value corresponding to a state of first-order self-phase locking of the laser. As a result, the spectral shape of the laser signal does not remain Lorentzian but collapses around the carrier to a delta function with a close to carrier noise level of less than -137 dBc/Hz. The total phase variance of this laser signal, in a 20 GHz noise bandwidth, is less than 0.002 rad^