Quantum-dot semiconductor waveguide devices

Abstract

We have designed, fabricated and characterized self-assembled InAs/InGaAsP QD-waveguide devices around 1.55 μm. In order to obtain optimal performance, we have investigated several QD-based semiconductor optical amplifiers (SOAs) / lasers with different core geometry and doped profiles. To make the fair comparison between QD-SOA and QW-SOA, InAs/InGaAsP QW-SOAs with the same structure and the doped profiles have been designed and characterized. The experimental results indicate the QD-SOA is much better than QW-SOA in term of optical spectral bandwidth, temperature sensitivity and output power stability. The 3-dB and 10-dB bandwidths of the amplified spontaneous emission (ASE) spectra of the QD-SOA are 150 nm and 300 nm around 1520 nm. By using CW pump and probe signals we have demonstrated a non-degenerated four-wave mixing (ND-FWM) process and the experimental results indicate that the asymmetry of the FWM conversion efficiencies is eliminated by using the QD-SOA. To make use of the inhomogeneous broadening which is one of the specific properties of QD waveguide devices, we have designed and investigated the QD-based multi-wavelength semiconductor laser. A stable multi-wavelength laser output with a 93-channel multi-wavelength laser with maximum channel intensity non-uniformity of 3-dB were demonstrated on the basis of a single InAs/InGaAsP QD F-P cavity chip. All channels were ultra-stable because of the inhomogeneous gain broadening due to statistically distributed sizes and geometries of self-assembled QDs.