We investigate the phase coherence between a seed laser and a laser amplified by a tapered semi conductor amplifier (TSA) when the seed laser is either continuous wave (CW) or pulsed. The phase fluctuations in the time domain are employed to describe the degradation of phase coherence induced by a TSA. The amplified laser is measured to be approximately 99.98% coherent with the seed, when the CW or pulsed laser is seeded, at different supplying currents of the TSA. Furthermore, the phase coherence is measured when the seed laser is modulated. The results reveal that the phase coherence degradations induced by the TSA remain the same for a seed laser with and without modulation, when different supplying currents of the TSA are applied.
© 2009 Optical Society of America
Coherence and Statistical Optics
Original Manuscript: April 7, 2009
Revised Manuscript: July 6, 2009
Manuscript Accepted: July 9, 2009
Published: July 22, 2009
Xiang Hui Qi, Lin Yi, Qian Li Ma, Da Wei Zhou, Xiao Ji Zhou, and Xu Zong Chen, "Study of phase coherence degradation induced by a tapered semiconductor amplifier with frequency-modulated continuous-wave and pulsed seed lasers," Appl. Opt. 48, 4370-4374 (2009)