A Temporal Coherence Study of Quantum-Dot/Dash Broadband Lasers and Superluminescent Diodes

The temporal coherence functions of InGaAs-GaAs quantum-dot (QD) and InAs-InGaAlAs quantum-dash (Qdash) superluminescent diodes (SLDs) and broadband laser diodes (BLDs) are reported. Using an optical fiber-based spectral interferometer, the fabricated devices were shown to yield low coherence lengths of 4.00-12.29 mum and 33.48-74.56 mum for SLD and BLD devices, respectively. In addition, there were negligible secondary coherencies indicating that these devices have the potential for use in low coherent interferometric systems.