1.3-µm quantum-dot optical preamplifier with narrow bandwidth

The authors developed and characterized a quantum dot semiconductor optical amplifier (QD-SOA) preamplifier with a narrow bandwidth for CWDM at 1.3 μm. The narrow 3-dB bandwidth that stemmed from the discrete energy states was found to be 30 nm at 1.3 μm. At a shorter wavelength of 1260 nm, the transmitted optical power decreased by 10 nW at a current of 60 mA. Additionally, the QD preamplifier could operate over an arbitrary spectrum if we realize a pure homogeneous QD with a delta-like energy state. Thus, this device could be used to realize a low-cost CWDM network without requiring filters at 1.3 μm because the optical power is decreased for signals outside the selected spectrum.