High-Speed, Directly-Modulated Widely Tunable 1310 nm Coupled Cavity Laser Via Multimode Interference

We discuss the design and demonstration of a widely tunable laser operating at 1310 nm with ∼38 nm tuning range, >35 dB side-mode-suppression-ratio (SMSR), and output powers of ∼3 mW per tuning wavelength. Greater than 50 channels are demonstrated on a material platform that consists of In
_0.70
Al
_0.17
Ga
_0.13
As multiple quantum wells (MQW) and Al
_0.52
In
_0.48
As electron stop layers for high temperature operation. Various single-side facet power wall-plug-efficiency (WPE) values of 8–1% are reported for operating temperatures of 30–70 °C, respectively. We compare theoretical and experimental data on the impact that multi-mode-interference (MMI) coupling coefficient values have on SMSR. We also discuss the integration of on-chip mode-converters to facilitate low-loss edge coupling to silicon photonic integrated circuits (Si-PICs). Directly-modulated, small-signal frequency measurements show 3-dB modulation bandwidths up to 14 GHz. The absence of epitaxial re-growth and lithographically demanding sub-wavelength gratings lends itself to high operating temperature, reliable and low-cost tunable light sources with device sizes of ∼400 μm × 300 μm.