Analysis of Timing Jitter in External-Cavity Mode-Locked Semiconductor Lasers

Abstract

Abstract-We develop a comprehensive theoretical description of passive mode-locking in external-cavity mode-locked semiconductor lasers based on a fully distributed time-domain approach. The model accounts for the dispersion of both gain and refractive index, nonlinear gain saturation from ultrafast processes, selfphase modulation, and spontaneous emission noise. Fluctuations of the mode-locked pulses are characterized from the fully distributed model using direct integration of noise-skirts in the phase-noise spectrum and the soliton perturbations introduced by Haus. We implement the model in order to investigate the performance of a MQW buried heterostructure laser. Results from numerical simulations show that the optimum driving conditions for achieving the shortest pulses with minimum timing jitter occur for large reverse bias in the absorber section at an optimum optical bandwidth limited by Gordon-Haus jitter.

Theory of passively mode-locked photonic crystal semiconductor lasers

“…(3). It is seen that the pulse width reaches the sub picosecond range when k (2) ω 0 is around −2.1 × 10 6 ps 2 /km and from Fig. 9(a) it is evident that k (3) ω 0 can attain large values without significant pulse distortion, when the value of k (2) ω 0 is in this optimum range.…”

“…The closer k (2) ω 0 is to −2.1 × 10 6 ps 2 /km, the more this dip opens due to an increasing lag of the trailing pulse and the ratio decreases while the width of the trailing pulse increases. The symmetry line at k (2) ω 0 = −2.1 × 10 6 ps 2 /km in Fig. 9(a) and 9(b) corresponds to a zero value of the second order term, [k…”

“…Following the model in [9], these effects are, however, not included here. Random spontaneous emission noise [1,2] is also not considered in this work. The model does not assume small round trip gain or loss as in [12], which makes it suitable for semiconductor active materials.…”

“…the traveling wave equation [20], predicts the symmetry line to be placed at k (2) ω 0 = 0. The translation of this line in Fig.…”

“…Pulse properties such as the width and chirp can be tuned via the PC dispersion. Also, engineering of the waveguide geometry provides control over the optical density of states, which changes the spontaneous emission and thereby affects the dynamics and noise properties of the laser [1,2]. High quality monolithic passive mode-locked lasers suitable for optical communication systems have already been demonstrated [3], but for dense integration on photonic chips, the PC structures offer the possibility for the necessary size reduction [4].…”