Long-Wavelength InGaAs/GaAs Quantum Dot Lasers

Injection lasers for the spectral range beyond 1.2 μm play an important role in many areas, from material processing to telecom applications. The wavelength range near 1.28–1.32 μm is particularly important for datacom applications at distances up to 2–10 km, with an advantage of ultrafast data links based on time division multiplexing (TDM) and, more recently, coarse wavelength division multiplexing (CWDM) systems. High-power single transverse mode long-wavelength laser diode pumps are required for the 14xx–15xxnm wavelength range, where Raman fiber amplifies for long-haul telecom applications are used for dense wavelength division multiplexing (DWDM) systems. Cost-effective wavelength-tunable vertical cavity surface emitting lasers (VC-SELs) are needed for the 1.5–1.65 μm range used in DWDM. However, this classification became to some extent obsolete after the appearance of Lucent Technologies™ ‘AllWave™’ fiber which does not contain an OH+ absorption hump between the 1.3 μm and 1.5 μm fiber transparency windows. In the near future all applications between 1.2 and 1.7 μm may be merged in unified CWDM/DWDM systems (transmitters, Raman amplifiers). Long-wavelength lasers are also needed for eye-safe lidar for terrestrial and free-space applications.