Compact dual-wavelength InAs/GaAs quantum-dot external-cavity laser stabilized by a single volume Bragg grating

Stable dual-wavelength operation has been achieved by combining a single volume Bragg grating with a quantum-dot-based gain medium in a compact external cavity configuration, with extreme ease of alignment. The dual-wavelength output was centered at 1179.9 and 1182.8 nm, with each mode exhibiting a spectral bandwidth ∼ 0.2 nm. A maximum output power of 186 mW was achieved, with both modes displaying a sidemode suppression-ratio (SMSR) of over 34 dB. Furthermore, the SMSR remained well over 26 dB within a broad current range (350-1000 mA) and temperature range (10.5°C-40°C). Unlike previous dual-wavelength configurations that used quantum-well-based devices, the quantum-dot-based laser here presented displays improved stability and resilience to changes in operating temperature and current.