Quantum dot-in-a-well laser applications in analog optical links

Radio-over-fiber (RoF) techniques are widely used in modern communication systems. A typical RoF system referred to as an analog optical link (AOL) consists of a laser diode employing direct or external modulation, an optical fiber, and broadband photo detectors (PDs). Recently, quantum dot (QD) lasers based on self-organized InAs/InGaAS QDs placed in quantum wells (QWs) have been developed characterized by extremely low threshold current densities, high temperature stability, high linearity, large bandwidth, and low noise. We proposed QD lasers with DWELL structure (QDWELL lasers) as promising candidates for the improvement of the AOL performance. We have studied theoretically the performance of the QDWELL laser based AOL in the case of the multiband (MB) OFDM UWB signal transmission. We evaluated the spectrum of the baseband signal and the constellation diagram. The performance of AOL based on the QDWELL laser is significantly improved up to 10 GHz for small UWB signals.