Investigation Into the Phase Noise of Modulated Grating Y-Branch Lasers

Theoretical and experimental investigations of the phase noise of modulated grating Y-branch (MGY) lasers are presented, mainly focusing on influence of the additive Vernier effect. A comprehensive simulation model based on transmission line model is developed, taking into account the spontaneous emission noise in the active section, the carrier shot noise in the passive sections, the 1/f noise for the injection currents and the detuned-loading effect induced by the grating reflectors. The phase noise characteristics of the MGY laser and the SGDBR laser are simulated, and compared to find the difference between the additive and multiplicative Vernier effects. The results clearly indicate that the MGY laser exhibits more serious phase noise due to using the additive Vernier effect. It has been found that different super-mode selection methods lead to different reflection characteristics, which play an important role in determining the phase noise. Finally, the phase noise of the MGY laser and the SGDBR laser are measured by using a coherent phase noise measurement technique, the experimental results turn out to be in agreement with the simulations.