Timing characterization of 100 GHz passively mode-locked discrete mode laser diodes

TL;DR

This paper characterizes the timing stability of 100 GHz passively mode-locked discrete mode diode lasers, demonstrating low timing jitter and stable RF linewidth, with implications for high-speed optical applications.

Contribution

It provides the first detailed timing characterization of 100 GHz discrete mode diode lasers, showing that spectral filtering does not impair their timing performance.

Findings

20 fs pulse-to-pulse timing jitter in the first device

1 MHz RF linewidth in the second device

Spectral filtering does not negatively impact timing stability

Abstract

We report on the characterization of the timing stability of passively mode-locked discrete mode diode laser sources. These are edge-emitting devices with a spatially varying refractive index profile for spectral filtering. Two devices with a mode-locking frequency of 100 GHz are characterized. The first device is designed to support a comb of six modes and generates near Fourier limited 1.9 ps pulses. The second supports four primary modes resulting in a sinusoidal modulation of the optical intensity. Using a cross-correlation technique, we measured a 20 fs pulse to pulse timing jitter for the first device, while, for the second device, a mode-beating (RF) linewidth of 1 MHz was measured using heterodyne mixing in a semiconductor optical amplifier. Comparison of these results with those obtained for an equivalent Fabry-Perot laser indicates that the spectral filtering mechanism employed does not adversely affect the timing properties of these passively mode-locked devices.