Compact Low-Power Consumption Single-Mode Coupled Cavity Lasers

Ultra-compact, widely-tunable and low-power InP-based four-section coupled-cavity lasers are designed and analyzed. Two Fabry-Pérot cavities of unequal lengths, each containing an amplifier and a phase-tuning section, are coupled together through low-loss Bragg grating. The theoretical analysis of such multisection lasers starts with calculating the poles of a linear transfer function of the entire resonator in order to obtain resonant wavelengths and wavelength-dependent threshold gains. The differential quantum efficiency and the power-current characteristics are then calculated to evaluate the laser performance. The effectiveness of the design procedure is verified by the experimental and proof-of-principle demonstration using simplified three-section lasers. Devices exhibit single-mode operation with a side-mode suppression ratio of over 24 dB and tuning range of 11.2 nm. These telecom-suitable lasers can be used as on-chip local oscillators in low-power integrated optical coherent receivers.